Systems and methods for detecting and controlling charged droplets

Abstract

Described herein are systems and methods for detecting and / or controlling the direction of a moving charged droplet. The systems and methods are useful for determining the position of the charged droplet in real time based on a signal induced in an electrode of a sensor surrounding an aperture through which the charged droplet passes during flight from a source to a target. The signal from the sensor electrode can be measured and used to determine the position or trajectory of the droplet. The systems and methods are useful for correcting the trajectory of the charged droplet in real time, such as based on a determined position identified as having a trajectory that deviates from the target. The trajectory can be corrected by applying a voltage to an electrode surrounding an aperture through which the charged droplet passes during flight from a source to a target.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of and priority to U.S. Provisional Application No. 63 / 154,633, filed February 26, 2021, which is incorporated herein by reference in its entirety. [Background technology]

[0002] background The discovery of new and useful materials, the characterization of materials, the performance of tests, and other such procedures can depend on the ability to create and characterize new compositions of matter. As a result, recent research related to the physical, chemical, biological, or other properties of materials has focused on the development and implementation of methods and systems for synthesizing and evaluating potentially useful compounds, as well as the performance and analysis of various materials. In particular, rapid combinatorial methods have been developed to address the general need in the art for systematic, efficient, and economical materials synthesis techniques, as well as methods for analyzing and screening novel materials for useful properties.

[0003] Rapid combinatorial methods often involve the use of array technologies, which require precise dispensing of liquids with precisely known chemical compositions, concentrations, stoichiometries, reagent ratios, and / or volumes. Such array technologies can be used to perform a variety of synthetic processes and evaluations. Array technologies can use a large number of different fluids to form multiple reservoirs that, when properly arranged, yield combinatorial libraries. Many fluid dispensing technologies have been investigated to perform combinatorial techniques, including pin spotting, pipetting, inkjet printing, and acoustic ejection.

[0004] However, many of these techniques have inherent drawbacks that must be addressed before achieving the fluid dispensing precision and efficiency required for combinatorial methods. For example, many fluid dispensing systems are constructed using networks of tubing or other fluid transfer vessels. Tubing, in particular, can trap air bubbles, and trapped particles can clog nozzles. This can result in system failure and erroneous results. Furthermore, cross-contamination between compound library reservoirs can occur due to insufficient flushing of tubing and pipette tips between fluid transfer events. Cross-contamination can easily lead to inaccurate and misleading results.

[0005] Acoustic ejection offers many advantages over other liquid dispensing technologies. In contrast to inkjet devices, nozzleless or tipless fluid ejection devices are not susceptible to clogging and its associated drawbacks, such as misdirected fluid or improper droplet size. Furthermore, acoustic ejection does not require the use of tubing or involve invasive mechanical actions, such as those associated with introducing a pipette tip into a liquid reservoir, and thus may, among other things, reduce the risk of contamination. Furthermore, acoustic ejection can achieve higher levels of precision and accuracy and can be used to dispense very small amounts of liquid, potentially significantly reducing reagent costs.

[0006] Acoustic ejection has been described in many patents. For example, U.S. Patent No. 4,308,547 to Lovelad et al. describes a droplet emitter that utilizes acoustic principles to eject droplets from a body of liquid onto a moving document to form characters or barcodes on the document. A nozzleless inkjet printing device is used in which controlled ink droplets are propelled by acoustic forces generated by a curved transducer at or below the ink surface. Similarly, U.S. Patent No. 6,666,541 describes a device for acoustically ejecting multiple droplets toward and depositing them at discrete locations on a substrate surface. The device includes an acoustic radiation generator that can be used to eject fluid droplets from a reservoir and to generate detection acoustic waves that are transmitted to the fluid surface of the reservoir and result in reflected acoustic waves. The characteristics of the reflected acoustic radiation can then be analyzed to evaluate the acoustic energy level generated by the acoustic radiation generator at the fluid surface. Acoustic ejection may therefore offer an additional advantage in that the appropriate use of acoustic radiation provides feedback related to the process of acoustic ejection itself.

[0007] Variations in the initial conditions of droplet formation at the meniscus, including droplet velocity and direction, as well as variations in the forces acting on the droplet during its flight path, such as air resistance and electrostatic forces acting on charged droplets, result in variations in droplet placement at the target.

[0008] When the target is a well in a destination microplate and multiple droplets are being transferred, it is desirable for all droplets to coalesce and merge into a single large droplet at the target, however, in some cases the droplets may land on the target in a shattered fashion.

[0009] Many prior solutions rely on passive approaches to minimize sources of variation. Some exemplary techniques “suppress” the meniscus to reduce fluid surface variations, but this does not provide a “whole” solution. Typical existing solutions require some type of calibration solution for non-real-time droplet placement verification, which can be a time-consuming manual process. For example, liquid-sensitive paper can be used to determine where droplets land after a test droplet ejection. In addition to being time-consuming and manual, such non-real-time processes do not allow for timely adjustments and can potentially result in significant costs due to droplet ejection failures. While some existing solutions can verify droplet placement in real time, they require the use of large, expensive, and complex machinery. For example, certain optical systems, such as phase Doppler interferometer systems, can be used to detect droplet position in real time, but these are large, expensive, and typically use laser systems, which are desirable to avoid.

[0010] There is a need in the art for improved methods and apparatus that can accurately detect and provide real-time data on droplet ejection, droplet velocity, and droplet position during transport without relying on bulky and expensive optical lasers. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] U.S. Patent No. 4,308,547 [Patent Document 2] U.S. Patent No. 6,666,541 Summary of the Invention [Problem to be solved by the invention]

[0012] summary Examples of inventions covered by this disclosure are defined by the claims that follow, rather than by this summary. This summary is a high-level overview of various aspects and introduces some of the concepts that are further described in the "Detailed Description" section below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used alone to determine the scope of the claimed subject matter. The subject matter should be understood by reference to the entire disclosure, including the following description, all drawings, and claims.

[0013] While typical systems rely on manual calibration and / or large, expensive optical tracking systems for droplet ejection tracking of acoustic droplet ejectors, the devices, systems, and methods provided herein enable real-time tracking and control of charged droplets in a compact, low-cost system. While the examples described herein may illustrate and be referenced to acoustic droplet ejection systems, the techniques and systems described herein may be applied to pressure-based systems (e.g., inkjet), microfluidic systems, or any other suitable droplet generation system or component (e.g., fluorescence-activated cell sorters, fluorescence-activated single-drop dispensers, precision micropump systems, piezoelectric-based active droplet generators, etc.). While real-time tracking can be achieved using optical tracking systems, such systems can add additional complexity to the droplet ejection system and impact system usability. Other approaches to non-real-time tracking require manual calibration and can disrupt workflow. The real-time measurements described herein provide improved efficiency in manufacturing workflows and rapid optimization of droplet generator calibration. The real-time control schemes described herein further provide precision and repeatability of droplet positioning, allowing for a real-time feedback system to avoid repeated calibrations. The present systems and methods may also enable efficient coupling of a droplet generator (e.g., an acoustic droplet ejection system) to the inlet of a secondary device, such as a mass spectrometer or other analytical system. The devices, systems, and methods described herein are particularly useful for real-time tracking and control, for example, to verify or align droplet placement in a mass spectrometer or other analytical system during sample placement for analysis. [Means for solving the problem]

[0014] The present disclosure provides systems for detecting, monitoring, and controlling charged droplets from a droplet generator, such as an acoustic droplet ejection system. One general aspect includes a device for detecting and / or controlling charged droplets from a droplet generator. The device may include a sensor or control element (e.g., a multilayer printed circuit board) having one or more conductive layers separated or supported by insulating layers, the sensor or control element defining an opening in the device through which the charged droplets pass. In some examples, the sensor or control element may be fabricated as a multilayer printed circuit board, although those skilled in the art will understand that the sensor or control element may take any suitable form. In some embodiments, droplets ejected by a droplet generator may be required to reach a target within a certain tolerance. For example, certain applications may impose a placement tolerance within some dimension of the droplet diameter (e.g., within 100%, 75%, 50%, 25%, 10%, or 5% of the droplet diameter). Such a placement tolerance may ensure, for example, that droplets reach a target or that different droplets do not coalesce upon reaching the target. In some cases, droplets may arrive off-target by up to about 200% of the droplet diameter (e.g., a 2.5 nL droplet with a diameter of 168 microns may arrive 400 microns away from the target). In preferred cases, droplets consistently land on the target location or within a distance of up to 125% of the droplet diameter from the target location, with fewer than 1 in 1000 droplets landing farther than 125% of the droplet diameter from the target location. After the initial droplet, subsequent droplets directed at the target location may desirably fuse, coalesce, and mix into a single larger droplet. In ideal cases, there should be no off-target droplets, scattering, or scattered landings isolated from the main droplet. Droplet placement on the target may allow for the widest possible range of initial droplet velocity and direction at droplet formation, as well as variation along the droplet flight path. In some examples, the target may be an inlet or orifice associated with a microplate, a microfluidic device, or a well in an analytical instrument, device, or system. The droplets may be of a size that allows them to adequately reach the target without impacting the sides or walls of the inlet or orifice.For example, the orifice can have a diameter of about 130% or more of the diameter of the droplet, such as about 150%, 200%, 250%, 300%, 350%, 400%, 450%, 500% or more of the diameter of the droplet, or a diameter of from about 130% to about 1000% of the diameter of the droplet.

[0015] In some examples, the sensor element may include three or more conductive layers and two or more insulating layers. In one example, an inner layer of the sensor element may include a segmented conductive layer having multiple divided segments that are electrically isolated or independent from one another, and the multiple divided segments are arranged around an opening in the segmented conductive layer. The device may also include a circuit element (e.g., one or more transimpedance amplifiers) electrically coupled to each of the divided segments. Each divided segment of the sensor element is arranged to provide an induced current to the circuit element when a charged droplet passes through the opening. The circuit element may include one or more transimpedance amplifiers that generate a measurement (e.g., a voltage signal) proportional to the induced current. The device may also include one or more computing devices or means that can receive the measurement from the circuit element and generate a weighting map that identifies the position of the charged droplet within the opening based on the magnitude of the measurement. In some examples, the signal may be processed by a computing device, circuitry, an analog-to-digital converter, software, or other such system.

[0016] In some examples, the control element may include one or more conductive layers and one or more insulating layers. In one example, the conductive layer of the control element may include a segmented conductive layer having multiple divided segments that are electrically insulated or independent from one another, the multiple divided segments being arranged around an opening in the segmented conductive layer. The device may also include one or more voltage generators and / or voltage controllers for applying a potential to each of the divided segments to generate an electric field of sufficient orientation and magnitude to change the trajectory of the charged droplet as it passes through the opening. The device may also include one or more computing devices or means capable of determining the voltage to apply to each of the divided segments to achieve a particular deflection of the droplet trajectory. In some cases, the voltage may be determined based on or using a signal representative of or useful for deriving the position of the charged droplet, determined by passing the charged droplet through the sensor element. In some examples, the signal may be processed by a computing device, circuitry, analog-to-digital converter, software, or other such system to determine the appropriate voltage to apply to the divided segments of the conductive layer.

[0017] In another example, a system for detecting charged droplets from a droplet generator may include a sensing device having an opening formed therein from a first surface to a second surface, the sensing device including a first conductive layer at the first surface, a second conductive layer at the second surface, a segmented sensor layer between the first and second conductive layers, and first and second dielectric layers disposed on opposing surfaces of the segmented sensor layer that insulate the segmented sensor layer from the first and second conductive layers. The segmented sensor layer may include multiple segments disposed around the opening. The system may also include a circuit element coupled to each of the multiple segments of the segmented sensor layer. In some examples, the circuit element includes one or more transimpedance amplifiers. The system may also include a processor and a non-transitory computer-readable medium having stored thereon instructions that, when executed by the processor, cause the processor to perform operations including receiving, from one or more circuit elements coupled to the segmented sensor layer, multiple measurements corresponding to induced currents passing through segments of the segmented sensor layer as the charged droplet passes through the opening, and determining a position of the charged droplet based on the measurements.

[0018] In another example, a system for detecting charged droplets from a droplet generator may include a control device having an aperture formed therein and including a segmented conductive layer. The segmented conductive layer may include multiple segments arranged around the aperture. The system may also include a voltage controller coupled to each of the multiple segments of the segmented conductive layer. In some examples, the voltage controller may be driven to generate a potential on each of the segmented conductive layer to establish an electric field at the aperture. The system may also include a processor and a non-transitory computer-readable medium having stored thereon instructions that, when executed by the processor, cause the processor to perform operations including applying a set of control voltages to the multiple segments using the voltage controller to control the trajectory of the charged droplets as they pass through the aperture. The set of control voltages may be generated based on, for example, the determined position or velocity of the charged droplets.

[0019] In another aspect, methods are described herein, such as methods for detecting or controlling charged droplets from a droplet generator or the like. In some examples, the methods may be performed by or using the systems described herein. In some examples, the methods of this aspect may include disposing a charged droplet detector and / or a charged droplet controller between the droplet generator and a target and directing charged droplets from the droplet generator toward the target through an aperture in the charged droplet detector and / or the charged droplet controller. The methods of this aspect may include analyzing a voltage signal generated by the charged droplet detector as the charged droplets pass through the aperture to determine the position of the charged droplets. The methods of this aspect may include determining and / or applying a voltage to a segment of a segmented control layer to alter the trajectory of the charged droplets, e.g., by determining a voltage based on the determined position of the charged droplets or determining a signal from which the position of the charged droplets can be derived. Other examples of this aspect include corresponding devices and systems, each configured to perform the operations of the method. In some cases, the methods of the present disclosure, or portions thereof, may be performed during execution of processor-executable instructions.

[0020] In another aspect, a method for adjusting ejection parameters based on monitored charged droplets in an acoustic droplet ejection system is described herein. In some examples, the method is performed using a system described herein, including an acoustic droplet ejection system, a sensing element, and other systems described herein. The method may include applying an acoustic signal to a fluid using an acoustic droplet ejection system coupled to a reservoir to eject a first droplet from the reservoir through an opening in a charged droplet detector toward a target. The method may also include determining that the acoustic signal caused the ejection of a satellite droplet based on a measurement of a value corresponding to an induced current passing through the charged droplet detector. The method may further include adjusting parameters of the acoustic droplet ejection system based on the determination to prevent or reduce the ejection of satellite droplets in subsequent ejections. In some examples, the disclosed methods, or portions thereof, may be performed during execution of processor-executable instructions. The present invention provides, for example, the following. (Item 1) 1. A device for detecting or controlling charged droplets from a charged droplet generator, comprising: A sensor element having three or more conductive layers separated by insulating layers, the conductive layers and the insulating layers defining an opening in the sensor element through which charged droplets pass, and an inner layer of the three or more conductive layers being a segmented conductive layer having a plurality of divided segments that are electrically independent of one another and are arranged around the opening in the segmented conductive layer; and a circuit element electrically coupled to each of the divided segments, wherein each divided segment of the plurality of divided segments is arranged to provide an induced current to the circuit element when a charged droplet passes through the opening, the circuit element being configured to generate a signal proportional to the induced current; Including, the device. (Item 2) (i) each of the plurality of divided segments is disposed at a corresponding portion around the opening; (ii) each of the plurality of divided segments occupies an equal portion of the perimeter of the opening as one or more other divided segments; (iii) an outer conductive layer of said three or more conductive layers is held at ground or reference potential; (iv) the circuit element includes a transimpedance amplifier; (v) the signal proportional to the induced current comprises a voltage signal; (vi) the plurality of segmented segments includes at least two pairs of segmented segments, the segmented segments of one pair of segmented segments being disposed opposite each other around the opening, and optionally each pair of segmented segments being disposed perpendicular to another pair of segmented segments; or (vii) the sensor element is disposed between a source and a target destination of a charged droplet generator, and optionally the opening is aligned with an ejection axis of the charged droplet generator; Item 1. The device according to item 1. (Item 3) processor; and a non-transitory computer-readable storage medium in data communication with a processor, the non-transitory computer-readable storage medium, when executed by the processor, receiving a signal from a circuit element; and determining the position of the charged droplet based on said signal; a non-transitory computer-readable storage medium storing processor-executable instructions that cause a processor to perform operations including: further comprising Depending on the situation, (i) the operation further includes determining one or more of: the arrival time of the charged droplets at the opening; the velocity of the charged droplets; the charge-to-volume ratio of the charged droplets; or the presence of one or more charged satellite droplets; or (ii) determining the location of the charged droplet includes weighting each signal from the plurality of divided segments to determine a normalized signal; and determining the location of the charged droplet based on the magnitude of the normalized signal; and optionally, weighting each signal includes weighting each signal by the sum of all signals from the divided segments; or weighting each signal by a relative area or perimeter percentage of the corresponding divided segment. Item 1. The device according to item 1. (Item 4) A control element having a conductive control layer adjacent to one or more insulating layers, a control element, wherein the conductive control layer and one or more insulating layers define a second opening in the control element through which the charged droplet passes after passing through the opening in the sensor element, and the conductive control layer is a second segmented conductive layer having a second plurality of divided segments that are electrically independent of one another and are disposed around the second opening; and a voltage controller electrically coupled to each of the second plurality of divided segments, each divided segment of the second plurality of divided segments arranged to generate an electric field as the charged droplets pass through the second opening to control the trajectory of the charged droplets, the voltage controller configured to apply a voltage to each of the second plurality of divided segments to generate the electric field; Item 1. The device of item 1, further comprising: (Item 5) processor; and a non-transitory computer-readable storage medium in data communication with a processor, the non-transitory computer-readable storage medium, when executed by the processor, receiving a signal from a circuit element; determining the position of the charged droplet based on the signal; determining a set of voltages to apply to the second plurality of divided segments based on the positions of the charged droplets; and controlling a voltage controller to apply a set of voltages to the second plurality of divided segments; a non-transitory computer-readable storage medium storing processor-executable instructions that cause a processor to perform operations including Item 5. The device of item 4, further comprising: (Item 6) (i) the second opening is aligned with the opening of the sensor element; (ii) each of the second plurality of divided segments is disposed at a corresponding portion around the second opening; (iii) each of the second plurality of divided segments occupies an equal portion of the perimeter of the second opening as one or more other of the second plurality of divided segments; (iv) the second plurality of divided segments includes at least two pairs of divided segments, the divided segments of one pair of divided segments being disposed opposite each other around the second opening; (v) the control element is disposed between a source and a target destination of the charged droplet generator or between the sensor element and a target destination of the charged droplet generator; (vi) the control element further includes a reference or ground layer separated from the conductive control layer by one or more of the insulating layers, and the second opening is further defined by an opening in the reference or ground layer; or (vii) the control element includes two or more conductive control layers separated by an insulating layer and coupled to the voltage controller; Item 4. The device according to item 4. (Item 7) 1. A device for detecting or controlling charged droplets from a charged droplet generator, comprising: a control element having a conductive control layer adjacent to one or more insulating layers, the conductive control layer and the one or more insulating layers defining an opening in the control element through which charged droplets pass, the conductive control layer being a segmented conductive layer having a plurality of separated segments that are electrically independent of one another and are disposed around the opening; and a voltage controller electrically coupled to each of the plurality of divided segments, each divided segment of the plurality of divided segments being arranged to generate an electric field as the charged droplets pass through the opening to control the trajectory of the charged droplets, the voltage controller being configured to apply a voltage to each of the plurality of divided segments to generate the electric field. Including, the device. (Item 8) (i) each of the plurality of divided segments is disposed at a corresponding portion around the opening; (ii) each of the plurality of divided segments occupies an equal portion of the perimeter of the opening as one or more other divided segments; (iii) the control element is disposed between a droplet generator source and a target destination; (iv) the opening is aligned with the ejection axis of the charged droplet generator; (v) the plurality of segmented segments includes at least two pairs of segmented segments, the segmented segments of one pair of segmented segments being disposed opposite one another around the opening, and optionally each pair of segmented segments being disposed perpendicular to another pair of segmented segments; or (vi) Furthermore processor; and a non-transitory computer-readable storage medium in data communication with a processor, the non-transitory computer-readable storage medium, when executed by the processor, controlling a voltage controller to apply a set of voltages to the plurality of divided segments; a non-transitory computer-readable storage medium storing processor-executable instructions that cause a processor to perform operations including Including, Item 7. The device according to item 7. (Item 9) 1. A device for detecting or controlling charged droplets from a charged droplet generator, comprising: a first conductive layer on the first surface; a second conductive layer on the second surface; a segmented sensor layer between the first conductive layer and the second conductive layer; and first and second dielectric layers disposed on opposing surfaces of the segmented sensor layer, insulating the segmented sensor layer from the first and second conductive layers; the segmented sensor layer includes a plurality of segments arranged around the opening; a sensing device having an opening formed from a first surface to a second surface, a circuit element coupled to each of the plurality of segments of the segmented sensor layer; Including, the device. (Item 10) (i) the opening is aligned with the ejection axis of the charged droplet generator; (ii) the circuit element includes a transimpedance amplifier; (iii) the segmented sensor layer includes a plurality of electrically independent segments surrounding the opening, optionally the segmented sensor layer includes at least four segments, the at least four segments being arranged around the opening, each segment being arranged as a pair opposite another segment around the opening, and optionally each pair of segments being arranged perpendicular to another pair of segments; Item 9. The device according to item 9. (Item 11) processor; and a non-transitory computer-readable storage medium in data communication with a processor, the non-transitory computer-readable storage medium, when executed by the processor, receiving a plurality of measurements from one or more circuit elements coupled to the segmented sensor layer corresponding to or proportional to induced currents in the plurality of segments as the charged droplet passes through the aperture; and determining a position of the charged droplet based on the plurality of measurements; a non-transitory computer-readable storage medium storing processor-executable instructions that cause a processor to perform operations including further comprising optionally, the operation further comprises determining one or more of: an arrival time of the charged droplets at the opening; a velocity of the charged droplets; a charge-to-volume ratio of the charged droplets; or the presence of one or more charged satellite droplets. Item 9. The device according to item 9. (Item 12) a control device having a second opening formed therein, a segmented control layer, the segmented control layer including a second plurality of segments disposed about the second opening; and a voltage controller coupled to each of the second plurality of segments of the segmented control layer; a control device, Item 10. The device of item 9, further comprising: (Item 13) (i) the second opening is aligned with the opening of the sensing device; or (ii) the segmented control layer comprises a plurality of electrically independent segments surrounding the second opening, optionally wherein the segmented control layer comprises at least four segments, the at least four segments being arranged around the opening, each segment being arranged as a pair opposite another segment around the second opening, and optionally wherein each pair of segments is arranged perpendicular to another pair of segments; Item 13. The device according to item 12. (Item 14) processor; and a non-transitory computer-readable storage medium in data communication with a processor, the non-transitory computer-readable storage medium, when executed by the processor, receiving a plurality of measurements from one or more circuit elements coupled to the segmented sensor layer corresponding to or proportional to induced currents in the plurality of segments as the charged droplet passes through the aperture; determining a position of the charged droplet based on the plurality of measurements; determining a set of control voltages based on the position of the charged droplet; and applying the set of control voltages to the second plurality of segments using the voltage controller to change the trajectories of the charged droplets. a non-transitory computer-readable storage medium storing processor-executable instructions that cause a processor to perform operations including further comprising optionally, the set of control voltages is determined based on one or more of a position of the charged droplets, a velocity of the charged droplets, or a predetermined position of a target; Item 13. The device according to item 12. (Item 15) 1. A device for detecting or controlling charged droplets from a charged droplet generator, comprising: a control device having an opening formed therein, a segmented conductive layer, the segmented conductive layer including a plurality of segments disposed around the opening; and a voltage controller coupled to each of the plurality of segments of the segmented conductive layer; a control device, Including, the device. (Item 16) (i) the opening is aligned with the ejection axis of the charged droplet generator; or (ii) the segmented conductive layer comprises a plurality of electrically independent segments surrounding the opening, optionally wherein the segmented conductive layer comprises at least four segments, the at least four segments being arranged around the opening, each segment being arranged as a pair opposite another segment around the opening, and optionally wherein each pair of segments is arranged perpendicular to another pair of segments; Item 16. The device according to item 15. (Item 17) processor; and a non-transitory computer-readable storage medium in data communication with a processor, the non-transitory computer-readable storage medium, when executed by the processor, applying a set of control voltages to the plurality of segments using the voltage controller to control the trajectory of the charged droplets as they pass through the aperture. a non-transitory computer-readable storage medium storing processor-executable instructions that cause a processor to perform operations including further comprising optionally, the operation further includes determining the set of control voltages based on one or more of a known position of the charged droplets, a known velocity of the charged droplets, or a predetermined position of a target; Item 16. The device according to item 15. (Item 18) 1. A method for detecting or controlling charged droplets from a charged droplet generator, comprising: directing the charged droplets toward the target and through an opening in a charged droplet detector; measuring, in the charged droplet detector, a plurality of values ​​corresponding to an induced current generated when the charged droplet passes through the aperture; and analyzing the plurality of values ​​corresponding to the induced current to determine the position of the charged droplet. A method comprising: (Item 19) (i) further comprising determining a total charge of the charged droplets based on a plurality of values; (ii) further comprising reversing the polarity of the charged droplet detector to form a charged droplet gate; (iii) further comprising identifying satellite droplets based on the plurality of values; (iv) analyzing the plurality of values ​​to determine the location of the charged droplet; determining a difference between measurements from segments of the charged drop detector located on opposite sides of the opening of the charged drop detector; and determining a position along an axis between the segments located on opposite sides of the opening based on a difference between the measurements; Contains; or (v) directing the charged droplets includes directing the charged droplets through a second opening of a charged droplet controller, the method further comprising: determining a set of voltages to apply to the charged droplet controller to control the trajectory of the charged droplets toward a target, the set of voltages being determined based on the position of the charged droplets; and applying said set of voltages to a charged droplet controller; Including, optionally, determining the set of voltages includes determining a magnitude of a voltage to apply to a segment of the charged drop controller located opposite the second opening to modify a trajectory of the charged drop from a position of the charged drop at a charged drop detector toward a target; or (vi) further comprising determining one or more of: the arrival time of the charged droplets at the opening; the velocity of the charged droplets; the charge-to-volume ratio of the charged droplets; or the presence of one or more charged satellite droplets, and optionally, determining the velocity of the charged droplets comprises determining a time period between the ejection or generation signal of the charged droplets and one or more peaks of the plurality of values. Item 19. The method according to item 18. (Item 20) 1. A method for detecting or controlling charged droplets from a charged droplet generator, comprising: directing the charged droplets toward the target and through an opening in a charged droplet controller; and applying a set of voltages to the charged droplet controller to control the trajectory of the charged droplets toward a target. Including, In some cases, further determining a set of voltages to apply to a segment of the charged droplet controller located on an opposite side of the aperture to modify the trajectory of the charged droplet based on one or more of the known position of the charged droplet, the known velocity of the charged droplet, or a predetermined position of a target. A method comprising:

[0021] BRIEF DESCRIPTION OF THE DRAWINGS The nature and advantages of various examples may be further understood by reference to the following figures, in which like components or features may have the same reference labels. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 illustrates a droplet generator including a charged droplet management device, according to at least some examples. [Figure 2] FIG. 2 illustrates a droplet generator including a charged droplet detector and a charged droplet controller, according to at least some examples. [Figure 3]FIG. 3 illustrates an exploded view of a conductive layer of a charged drop detector, according to at least some examples. [Figure 4] FIG. 4 illustrates a side view of a charged droplet detector, according to at least some examples. [Figure 5] FIG. 5 illustrates a top view of a segmented conductive layer of a charged drop detector, according to at least some examples. [Figure 6] FIG. 6 illustrates a cross-sectional view of a charged drop detector showing electrical connections of conductive layers, according to at least some examples. [Figure 7] FIG. 7 illustrates an exploded view of the layers of a charged droplet controller, according to at least some examples. [Figure 8] FIG. 8 illustrates a side view of a charged droplet controller, according to at least some examples. [Figure 9] FIG. 9 illustrates a top view of a segmented conductive layer of a charged droplet controller, according to at least some examples. [Figure 10] FIG. 10 illustrates a cross-sectional view of a charged droplet controller showing electrical connections of conductive layers, according to at least some examples. [Figure 11] FIG. 11 depicts a chart illustrating differential current from opposing segments of a segmented conductive layer for different droplet displacement positions along the axis between the opposing segments, according to at least some examples. [Figure 12] FIG. 12 depicts a chart illustrating current flow from a segment of a segmented conductive layer due to a charged droplet moving through an aperture, according to at least some examples. [Figure 13] FIG. 13 illustrates voltage signals associated with the output from a transimpedance amplifier for example charged droplet placement within an aperture, according to at least some examples. [Figure 14] FIG. 14 illustrates a voltage signal output indicative of a detector signal of a droplet moving through an aperture, according to at least some examples. [Figure 15]FIG. 15 shows a depiction of the droplet positions of FIG. 14, according to at least some examples. [Figure 16] FIG. 16 illustrates voltage signal outputs showing detector signals of main and satellite droplets moving through an aperture, according to at least some examples. [Figure 17] FIG. 17 shows a depiction of the positions of the main and satellite droplets of FIG. 16, according to at least some examples. [Figure 18] FIG. 18 depicts a flowchart illustrating a process for detecting charged droplets ejected from a droplet generator, according to at least some examples. [Figure 19] FIG. 19 illustrates a top view of a conductive layer of a charged droplet controller, according to at least some examples. [Figure 20] FIG. 20 shows the relative positions of the charged droplets measured by two charged droplet detectors on opposite sides of the charged droplet controller during steering of the charged droplets by applying different voltage differences between segments of the charged droplet controller. [Figure 21] FIG. 21 shows the relative positions of the charged droplets measured by two charged droplet detectors on opposite sides of the charged droplet controller during steering of the charged droplets by applying different voltage differences between segments of the charged droplet controller. [Figure 22] FIG. 22 shows the relative positions of the charged droplets measured by two charged droplet detectors on opposite sides of the charged droplet controller during steering of the charged droplets by applying different voltage differences between segments of the charged droplet controller. [Figure 23] FIG. 23 depicts a flowchart illustrating a process for controlling charged droplets ejected from a droplet generator, according to at least some examples. [Figure 24] FIG. 24 depicts a flowchart illustrating a process for detecting and controlling charged droplets ejected from a droplet generator using a feedback mechanism, according to at least some examples. [Figure 25]FIG. 25 illustrates a block diagram of an example computing device, according to some examples. [Figure 26] FIG. 26 provides an overview of one example of a charged droplet ejection, detection, and control system, according to some examples. DETAILED DESCRIPTION OF THE INVENTION

[0023] Detailed Description The present disclosure describes devices, systems, and methods for detecting, monitoring, and / or controlling charged droplets in real time using compact, low-cost devices. The systems and methods of the present disclosure can achieve numerous benefits, including detecting the horizontal position of charged droplets (e.g., along the X-axis and Y-axis), measuring droplet velocity, detecting satellite droplets, measuring droplet charge, counting droplets, tracking droplets, and controlling droplet trajectories. In some examples, the devices, systems, and methods described herein can be useful for diagnostic measurements to align droplet generators, detect misdirection in the trajectories of ejected droplets, and / or correct misdirected droplets. Advantageously, such aspects can be performed in real time during droplet generation and can be used to provide feedback to modify or adjust system components, alignment, ejection parameters, etc.

[0024] In some examples, the electrical charge possessed by a droplet (droplet charge) can be correlated to the volume of a particular source fluid, and thus droplet volume can be predicted and / or determined using measurements of droplet charge across a large number of droplets. While typical systems rely on manual calibration and / or large, expensive optical tracking systems, the devices, systems, and methods provided herein enable real-time tracking and / or control of charged droplets in a compact, low-cost system. The real-time measurements enabled herein provide improved efficiency in manufacturing workflows and rapid optimization of droplet generators, such as calibration of acoustic droplet ejection systems. The disclosed systems and methods may also enable efficient coupling and precise alignment of droplet generators with the inlet of a secondary device, such as a mass spectrometer or other analytical system. The devices, systems, and methods described herein are particularly useful for real-time tracking, e.g., to verify droplet placement in a mass spectrometer or other analytical system during sample placement for analysis. The devices, systems, and methods described herein are also useful for controlling droplet trajectories in real time, optionally using a feedback mechanism whereby the position and / or trajectory of a droplet is determined and the trajectory of the droplet is adjusted, for example, to optimize droplet placement in a mass spectrometer or other analytical system during sample placement for analysis.

[0025] Droplet generation can include processes such as acoustic droplet ejection, in which droplets are acoustically actuated from a fluid reservoir and move toward a target surface or location, although the present disclosure is not limited to droplet generation using acoustic droplet ejection systems. Other systems, such as pressure-based, inkjet-based, and / or microfluidic droplet generators or ejection systems, may also be used. In some embodiments for acoustic droplet ejection, acoustic energy may be directed toward the fluid meniscus of a fluid contained within a reservoir of a sample container (e.g., a well in a microplate, a fluid sample tube, a microplate, a microfluidic device), or toward an inlet to an analytical instrument, system, or device, including a mass spectrometer or other instrument for analyzing chemical composition, genomic content, genome sequencing, particle size, bodily fluid, or cellular analysis (e.g., a cytometer, a hemocytometer), etc. In some embodiments, the droplet generator can be oriented to move droplets vertically upward toward a target surface or location. While droplets are described herein as moving upward, droplets may be transported in other directions, such as downward and / or laterally, in addition to upward, when practicing the systems and methods described herein. In acoustic droplet ejection systems, the trajectory of a droplet from the ejecting fluid meniscus to the target surface can deviate from its intended path due, at least in part, to static effects (e.g., tilt of the fluid meniscus, electrostatic charges on the plastic of the well) and dynamic effects (e.g., capillary waves within the well), potentially resulting in misguiding of the droplet at the target surface / destination. Similar misguiding can occur in other droplet generation systems due to static and / or dynamic effects. The systems and methods described herein enable real-time measurement of droplet misguiding, which allows for monitoring and potentially reducing droplet misguiding, for example, by implementing a droplet control scheme in which the droplet trajectory is adjusted.

[0026] When the target is a well in a destination microplate and multiple droplets are being transferred, it may be desirable for all droplets to fuse and coalesce into a single large droplet at the target. However, in some cases, droplets ejected from a droplet generator may reach the target location within a certain tolerance. For example, certain applications may impose a placement tolerance within some dimension of the droplet diameter (e.g., within 100%, 75%, 50%, 25%, 10%, or 5% of the droplet diameter). Such a placement tolerance may ensure, for example, that a droplet reaches the target or that different droplets coalesce upon reaching the target. In some cases, droplets may arrive off-target by no more than about 200% of the droplet diameter (e.g., a 2.5 nL droplet with a diameter of 168 microns may arrive 400 microns away from the target). In preferred cases, droplets consistently land on the target location or within a distance of 125% of the droplet diameter or less from the target location, with fewer than 1 in 1,000 droplets landing farther than 125% of the droplet diameter from the target location. After the initial droplet, subsequent droplets directed to the target location can desirably fuse, coalesce, and mix to form a single larger droplet. In the ideal case, there should be no off-target droplets, scattering, or scattered landings isolated from the main droplet. Droplet placement on the target may allow for the widest possible range of initial velocity and direction at droplet formation, as well as variation along the droplet flight path. In some examples, the target may be a well in a microplate, a microfluidic device, or an inlet or orifice associated with an analytical instrument. The droplets may be sized to adequately reach the target without impacting the sides or walls of the inlet or orifice. For example, the orifice can have a diameter of about 130% or more of the diameter of the droplet, such as about 150%, 200%, 250%, 300%, 350%, 400%, 450%, 500% or more of the diameter of the droplet, or a diameter of from about 130% to about 1000% of the diameter of the droplet.

[0027] In some cases, the target may be associated with a mass spectrometer (e.g., an open port probe (OPP) interface of a mass spectrometer) or other analytical instrument or system. The opening of the OPP may be defined, at least in part, by the coaxial arrangement (along the capillary axis) of the capillary and housing. In some such cases, a droplet placement tolerance of no more than about 125% of the droplet diameter from the vortex core (capillary axis) is a desirable feature to ensure accurate droplet placement within the OPP. In such cases, placing the droplet more than 125% of the droplet diameter from the target location may result in reduced ion counts and increased charge in the mass spectrometer. Droplet placement more than about 200% or 250% of the droplet diameter may result in missing ion count peaks.

[0028] According to examples described herein, the charged droplet management system may be positioned between the target and the droplet generator, such as between the target and a source well of an acoustic droplet ejection system. The charged droplet management system may include an opening that may be aligned with the ejection axis of the droplet generator (e.g., the transducer axis of the ejection system) so that droplets ejected by the droplet generator pass through the opening toward the target. The charged droplet management system may include one or both of a sensing or detection component and / or a control component. In either case, the charged droplet management system may include multiple segmented electrodes surrounding the opening.

[0029] When used as a charged droplet detector, when a charged droplet passes through an aperture, a current is induced in each segmented electrode and detected using a circuit element that converts each segment current into a corresponding output value. The output value may correspond to an induced current or a voltage value that represents or is proportional to the induced current. In some examples, the circuit element may include one or more transimpedance amplifiers. While the description herein may refer to a transimpedance amplifier, other suitable circuit elements may be implemented in place of a transimpedance amplifier. Since the sensor components and aperture geometry are known and predefined, the induced current may be modeled and determined. For example, the Shockley-Ramo theorem may be utilized to determine the droplet's charge, velocity, and / or trajectory based on the induced current in the segmented electrodes. Notably, the sum of all values, such as the induced current (and therefore the transimpedance amplifier voltage), may be directly related to the droplet's charge and velocity. Furthermore, the difference in signals from opposing segments around the aperture may be used to determine the lateral position of each droplet as it passes through the aperture.

[0030] When used as a charged droplet controller, each segmented electrode can be voltage-applied to generate an electric field that applies a force to the charged droplet to adjust its trajectory as it passes through the aperture. Various configurations of segmented electrodes can be used to enable precise adjustment of the trajectory of the charged droplet across two axes (e.g., the X-axis and the Y-axis). The voltage can be applied by one or more voltage controllers or other suitable components that can be implemented as or in place of a voltage controller.

[0031] FIG. 1 illustrates a system 111 having a charged droplet management device 110, according to at least some examples. As with all figures referenced herein, FIG. 1 is not to scale, and certain dimensions may be exaggerated for clarity of presentation. System 111 is shown to include a droplet generator 101 for generating charged droplets. While droplet generator 101 is depicted in FIG. 1 as an acoustic droplet ejection system, such a configuration is not limited, and other droplet generators may be used without departing from aspects described herein. System 111 illustrated in FIG. 1 is configured to accept a sample container 112, which may be a consumable product (e.g., a microplate, a fluid sample tube, or a well plate) having one or more reservoirs, optionally separate from system 111. For example, sample container 112 may include multiple reservoirs, i.e., two or more reservoirs, a first reservoir designated 113 and a second reservoir designated 115, each adapted to contain a fluid having a fluid surface, e.g., first fluid 114 and second fluid 116, having fluid surfaces designated 117 and 119, respectively. First fluid 114 and second fluid 116 may be the same or different. In some examples, sample container 112 may include only a single reservoir, and the systems and methods herein enable verification of successful droplet ejection, tracking of misdirection of droplets, and control of droplets from a single reservoir; however, systems and methods are contemplated in which droplets may be ejected, tracked, and / or controlled from multiple reservoirs. As illustrated, the reservoirs are substantially identically constructed so as to be substantially acoustically indistinguishable, although identical construction is not a requirement. Although the reservoirs are shown as separate, removable components, they may be fixed within a plate or other substrate if desired. For example, multiple reservoirs may comprise individual wells in a well plate, which may, but need not, be arranged in an array.Each of reservoirs 113 and 115 is preferably axisymmetric as shown, having vertical walls 121 and 123 extending upwardly from reservoir bases 125 and 127, respectively, and terminating in openings 129 and 131. The material and thickness of each reservoir base may be such that acoustic radiation can be transmitted therethrough to the fluid contained within the reservoir.

[0032] System 111 includes acoustic ejector 133, which includes acoustic radiation generator 135 that generates acoustic radiation and focusing device 137 that focuses the acoustic radiation near a fluid surface within the fluid from which droplets are to be ejected. As shown in FIG. 1 , focusing device 137 may include a single solid piece having a concave surface 139 for focusing the acoustic radiation, although focusing device 137 may be constructed in other manners as described below. Thus, acoustic ejector 133 is adapted to generate and focus acoustic radiation to eject droplets of fluid from each of fluid surfaces 117 and 119 when acoustically coupled to reservoir wells 113 and 115, and thus first fluid 114 and second fluid 116, respectively. Acoustic radiation generator 135 and focusing device 137 may function as a single unit controlled by a single controller or may be controlled independently, depending on the desired performance of the device. Typically, single-ejector designs are preferred over multiple-ejector designs because droplet placement accuracy and droplet size and velocity consistency are more easily achieved with a single ejector, although the present disclosure also contemplates that multiple ejectors may be used.

[0033] It will be appreciated that any of a variety of focusing devices 137 may be used in conjunction with the present invention. For example, one or more curved surfaces may be used to direct acoustic radiation to a focal point near the fluid surface. One such technique is described in U.S. Pat. No. 4,308,547 to Lovelady et al. Curved focusing devices 137 are incorporated into the construction of commercially available acoustic transducers, such as those manufactured by OLYMPUS CORP. (Waltham, Massachusetts). Additionally, Fresnel lenses are known in the art for directing acoustic energy to a predetermined focal distance from an object surface. See, for example, U.S. Pat. No. 5,041,849 to Quate et al. Fresnel lenses may have a radial phase profile that diffracts a substantial portion of acoustic energy into predetermined diffraction orders at diffraction angles that vary radially relative to the lens. The diffraction angles may be selected to focus the acoustic energy in the diffraction orders onto a desired object surface.

[0034] In operation, the device's reservoir wells 113 and 115 are filled with a first fluid 114 and a second fluid 116, respectively, as shown in FIG. 1. The acoustic ejector 133 is positionable using an ejector positioner 143, which may include an actuator that can move the acoustic ejector 133 to a desired position, for example, to achieve acoustic coupling between the ejector and the reservoir via an acoustic coupling medium 141. In FIG. 1, a substrate 145 is shown positioned above and near the first reservoir well 113, with one surface of the substrate facing the reservoir and positioned substantially parallel to or opposite a fluid surface 117 of the first fluid 114 therein. In some embodiments, the substrate 145 may be a sample container (e.g., a microplate, a sample tube) that includes a target area for droplet ejection. After the ejector, reservoirs, and substrate are properly aligned, acoustic radiation generator 135 is activated to generate acoustic radiation that is directed by focusing device 137 to a focal point 147 at or near fluid surface 117 of the first reservoir. As a result, droplets 149 are ejected from fluid surface 117 onto designated sites on the underside surface of substrate 145, including wells 155. In some cases, surface tension or capillary forces may assist or cause the ejected droplets to be retained on the substrate surface. Although not shown in FIG. 1 , the present disclosure contemplates that an analytical device, system, or instrument, such as a mass spectrometer (e.g., OPP), or other suitable target interface, may replace substrate 145.

[0035] The system 111 includes a substrate positioning device 150 that can be adjusted to reposition the substrate 145 over the reservoir 115 to receive droplets from the reservoir 115 at a second designated site. For example, the acoustic ejector 133 can be repositioned by the ejector positioner 143 below the reservoir 115 into acoustically coupled relationship thereto by the acoustic coupling medium 141. After proper alignment, the acoustic radiation generator 135 of the acoustic ejector 133 The focusing device 137 may be actuated to generate acoustic radiation that is then directed by the focusing device 137 to a focal point 148 at or near the fluid surface 119 of the second fluid 116, thereby ejecting additional droplets onto the substrate 145 in the well 157. It will be appreciated that such operation is illustrative of how the device may be used to eject multiple fluids from a reservoir to form a pattern, e.g., an array, on the substrate 145. It will also be appreciated that the device may be adapted to eject multiple droplets from one or more reservoirs onto the same site on the substrate 145.

[0036] 1 illustrates a particular configuration, this disclosure contemplates any suitable configuration that may readily adapt the disclosed concepts as appropriate. For example, system 111 may be oriented differently (e.g., acoustic ejector 133 positioned above substrate 145 so that droplets are ejected downward, or acoustic ejector 133 positioned to the side of substrate 145 so that droplets are ejected laterally).

[0037] As shown, system 111 includes a charged droplet management device 110 that can sense, detect, characterize, deflect, and / or manipulate the velocity or direction of charged droplets passing therethrough. In some embodiments, charged droplet management device 110 can include one or several conductive layers, as described further below. In some embodiments, system 111 can apply or impart a charge to droplets 149 before, during, or after ejection. Thus, droplets 149 can carry a net charge. The net charge can be induced on the droplets by applying a voltage to one or more layers of charged droplet management device 110. The voltage can generate an electric field at the fluid meniscus, inducing a net charge on the ejected droplets. In some examples, the natural charge of the droplets can be measured without an external electric field. Such a net charge can be imparted, for example, by applying a voltage or charge (e.g., a 1.5 kV bias) directly to the fluid 114 in FIG. 1, by passing the droplets through an additional biased conductive layer held at a reference voltage, e.g., a high voltage, placed between the reservoir and the charged droplet management device 110, or by applying a voltage bias to the entire charged droplet management device 110 or to part of the charged droplet management device 110.

[0038] The charge imparted to charged droplets can be positive or negative, depending on the voltage and / or electric field in the fluid 114 or meniscus. In some cases, the polarity of the charge imparted to the droplets can change, for example, from positive to negative or from negative to positive. The polarity can be changed by adjusting the voltage and / or electric field in the fluid or meniscus during droplet generation, for example, by switching the polarity of the voltage. The polarity can be changed periodically or aperiodically. In some cases, changing the polarity during droplet generation can reduce charge accumulation on the target (e.g., substrate 145) because negatively charged droplets can counteract previously generated and accumulated positive charge on the target and / or positively charged droplets can counteract previously generated and accumulated negative charge on the target. For sensing or controlling charged droplets by the charged droplet management device 110, the operation of using appropriate voltages for detecting or controlling positively or negatively charged droplets can be synchronized with the polarity of the droplets being generated. When used to direct charged droplets into a mass spectrometer or other analytical system, the operation of the mass spectrometer or other analytical system to analyze positively or negatively charged droplets can be synchronized with the polarity of the droplets generated.

[0039] Charged droplet management device 110 includes opening 109 through which droplets 149 travel from first reservoir well 113 to well 155. Opening 109 is aligned with transducer axis 118 of acoustic ejector 133. Without limitation, the opening of the charged droplet management device can have a diameter of 1 mm to 5 mm or more, e.g., 1 mm to 1.5 mm, 1.5 mm to 2 mm, 2 mm to 2.5 mm, 2.5 mm to 3 mm, 3 mm to 3.5 mm, 3.5 mm to 4 mm, 4 mm to 4.5 mm, or 4.5 mm to 5 mm. In some examples, the opening of the charged droplet management device can have a diameter larger than the diameter of the droplet, such as when the opening has a diameter greater than or equal to about 120% or less than about 500% of the diameter of the droplet. Without limitation, the openings may have a diameter that is about 120%, 130%, 140%, 150%, 160%, 170%, 180%, 190%, 200%, 225%, 250%, 275%, 300%, 325%, 350%, 375%, 400%, 425%, 450%, 475%, or 500% or more of the diameter of the droplet. In some cases, the diameter of the openings may be greater than 500% of the diameter of the droplet, for example, the diameter of the openings may be 3000% or 5000% or more of the diameter of the droplet.

[0040] In some examples, the charged droplet management device 110 can be positioned parallel to or at an angle to the surface of the first reservoir well 113. In some examples, the charged droplet management device 110 can be positioned obliquely at an angle to the first reservoir well 113.

[0041] Charged droplet management device 110 may be used to sense, detect, or characterize charged droplets in a configuration referred to herein as a charged droplet detector or charged droplet sensor. Alternatively or additionally, charged droplet management device 110 may be used to control the direction, velocity, or trajectory of charged droplets in a configuration referred to herein as a charged droplet controller. A charged droplet detector or charged droplet sensor may be advantageously useful for identifying the position of charged droplets passing through aperture 109, such as determining the lateral (e.g., X, Y) position of the charged droplets. Furthermore, a charged droplet detector may be used to determine the velocity, timing of the droplets (e.g., arrival at the aperture), total droplet charge, and / or the presence of one or more charged satellite droplets. A charged droplet controller may be advantageously useful for adjusting the trajectory of charged droplets by applying a force (e.g., an impact force) to steer the charged droplets (e.g., by causing a lateral deflection).

[0042] A feedback system may be included with or as part of the charged droplet management device 110 to enable the charged droplet detector to determine the lateral position of the charged droplets and provide a steering signal, such as a voltage signal, to the charged droplet controller that is determined based on the lateral position of the charged droplets. In this manner, the charged droplet management device 110 can identify misdirected charged droplets and adjust their trajectories so that they are received by their intended targets. For example, as described in further detail below, the charged droplet detector component of the charged droplet management device 110 can be used to generate current and / or voltage waveforms due to the passage of charged droplets, and such waveforms can be provided to a signal processing component to extract the position of the charged droplets at the charged droplet detector. The position of the charged droplet detector can be further analyzed and / or used, such as by a signal processing component or other processing component, to determine an appropriate steering voltage to apply to the charged droplet controller component of the charged droplet management device 110. In some examples, the steering voltage may be determined using a look-up table or function in which the position is provided as an input and the steering voltage is provided as an output.

[0043] In some examples, both a charged droplet detector and a charged droplet controller may be used, but they may be integrated into a single charged droplet management device or may be incorporated as separate components. Figure 2 shows an exemplary system 211, which may be the same as or different from system 111 shown in Figure 1, but which includes a charged droplet detector 210A and a charged droplet controller 210B in addition to the other components shown in system 111, including droplet generator 101 and substrate 145. In the illustrated configuration, charged droplet detector 210A is positioned near droplet generator 101, charged droplet controller 210B is positioned near substrate 145, and respective openings 209A and 209B are positioned relative to one another such that droplets 249 pass through both openings 209A and 209B as they move along axis 218 toward substrate 145. Such a configuration is not intended to be limiting. For example, instead, charged droplet controller 210B may be located closer to droplet generator 101, and charged droplet detector 210A may be located closer to substrate 145. In some examples, only charged droplet detector 210A is used, and charged droplet controller 210B is not present. In other examples, only charged droplet controller 210B is used, and charged droplet detector 210A is not present. In some cases, multiple charged droplet detectors 210A may be used. In some cases, multiple charged droplet controllers 210B may be used. In some examples, two charged droplet detectors 210A may be used with a single charged droplet controller 210B between them. Such a configuration may be useful in some examples to detect the position of charged droplets with a first charged droplet detector, correct the trajectory of the charged droplets with a charged droplet controller, and then detect the position of the charged droplets with a second charged droplet detector after the trajectory correction. Any suitable spacing or distance between components of the charged droplet management device (eg, between charged droplet detector 210A and charged droplet controller 210B) may be used.In some examples, the spacing between charged drop detector 210A and charged drop controller 210B can be between 25% and 400% of the diameter of opening 209A and / or opening 209B. In some examples, the spacing between components of a charged droplet management system (e.g., charged droplet detectors and / or charged droplet controllers) can be 0.1 mm to 10 mm or more, such as 0.1 mm to 0.5 mm, 0.5 mm to 1 mm, 1 mm to 1.5 mm, 1.5 mm to 2 mm, 2 mm to 2.5 mm, 2.5 mm to 3 mm, 3 mm to 3.5 mm, 3.5 mm to 4 mm, 4 mm to 4.5 mm, 4.5 mm to 5 mm, 5 mm to 5.5 mm, 5.5 mm to 6 mm, 6 mm to 6.5 mm, 6.5 mm to 7 mm, 7 mm to 7.5 mm, 7.5 mm to 8 mm, 8 mm to 8.5 mm, 8.5 mm to 9 mm, 9 mm to 9.5 mm, or 9.5 mm to 10 mm. In some examples, the spacing between components of the charged droplet management system can be the same as or greater than the diameter of the droplet, for example, the spacing can be greater than, about 100% of, or greater than the diameter of the droplet, including, but not limited to, spacing between charged droplet management components that is about 50%, 100%, 150%, 200%, 250%, 300%, 350%, 400%, 450%, 500%, 550%, 600%, 650%, 700%, 750%, 800%, 850%, 900%, 950%, 1000%, 1500%, 2000%, 3000%, 4000%, or 5000% or more of the diameter of the droplet.

[0044] In sensing, detecting, or characterizing charged droplets using a charged droplet detector, a current is induced in a conductive layer of the charged droplet detector as the charged droplet 149 or 249 moves through the opening 109 or 209A. The magnitude of the induced current may be related to the relative position of the charged droplet from the detector plate or a segment thereof, such as segments 366A, 366B, 366C, and 366D shown in FIG. 3 and segments 566A, 566B, 566C, and 566D shown in FIG. 5. For example, a segment producing a larger induced current may be relatively closer to the droplet 149 than other segments, and determining the difference between the induced currents of different segments may generate a weighting or scaling factor that can be used to identify the two-dimensional position (e.g., XY) of the droplet 149 as it passes through the opening 109 and the segment of the detector plate that it passed through.

[0045] 2, charged droplets 249 have a trajectory that causes them to arrive at wells 155 shifted from axis 218, which represents the intended target location of charged droplets 249 (e.g., in the absence of influence from charged droplet controller 209B). The lateral deviation of the charged droplets from axis 218 at opening 209A can be determined using charged droplet detector 210A, and such lateral deviation can be used to determine voltages to apply to components of charged droplet controller 210B to generate an electric field at opening 209B that deflects the trajectory of charged droplets 249 back toward the target location of well 155. .

[0046] FIG. 3 shows an exploded view of conductive layers of charged droplet detector 310, according to at least some examples. Charged droplet detector 310 may correspond to one implementation of charged droplet management device 110 of FIG. 1. Charged droplet detector 310 includes first conductive layer 360, second conductive layer 362, and sensor layer 361. When charged droplet 349 passes through an opening in charged droplet detector 310, such as an opening including or containing openings 363, 364, and 365, an induced current is generated in each segment of sensor layer 361 (e.g., segments 366A, 366B, 366C, and 366D in FIG. 3). Spacers or insulating regions 307 are disposed between segments 366A, 366B, 366C, and 366D to electrically isolate the segments from one another. The amount of induced current in each segment 366A, 366B, 366C, 366D may depend on the lateral position of the charged droplet 349 as it passes through the aperture 364 and the relative sizes of the segments. This induced current in each segment may be measured using one or more circuit elements. For example, a transimpedance amplifier may be connected to each segment, and such transimpedance amplifier may generate a measurable voltage output from each segment. As will be appreciated by those skilled in the art, such voltage output may be directly related to the induced current in the detector segment through the feedback resistance of the transimpedance amplifier by application of Ohm's Law. Thus, this disclosure contemplates that a charged droplet detector or associated system may measure voltage, current, or other measurements from which the induced current can be derived. While this disclosure contemplates that any suitable voltage / current / charge measurement circuit element may be used, the use of a transimpedance amplifier to measure the output voltage is provided as an example.

[0047] A droplet passing through the exact center of aperture 364 will induce equal currents in all four segments 366A, 366B, 366C, and 366D, assuming the segments are of equal dimensions, and therefore induce equal voltages at the outputs of the transimpedance amplifiers connected to the segments. A droplet misdirected from the center of the aperture and passing closer to one segment than another will induce a larger current in the closer segment and a smaller current in the farther segment as it travels through the device. These differences in induced currents can be adequately modeled by those skilled in the art, for example, using the Shockley-Ramo theorem. Similarly, differences in induced currents can be adequately modeled by those skilled in the art by considering the differences in magnitude for unequal segments 366A, 366B, 366C, and 366D in the model. The lateral position of the droplet passing through the aperture 364 of the charged droplet detector 310 may be extracted by measuring the difference between the signals detected from the various segments and appropriately normalizing or weighting, for example, by the sum of the signals from all sensors and / or the portion of the aperture perimeter occupied by each segment, or by some more complex method determined from the mode. The total charge on the droplet, or a signal proportional to the total charge on the droplet, may be extracted from the sum signal from all sensors, with a small correction made to account for the lateral displacement of the droplet from the aperture center measured using the difference signal.

[0048] In some examples, by measuring the measured current difference between signals detected from opposing segments, e.g., opposing segments along the X and / or Y axes (e.g., with reference to FIG. 3 , opposing segments 366A and 366C, opposing segments 366B and 366D), and appropriately normalizing or weighting, e.g., by a sum signal from all segments of sensor layer 361, or by using weighting coefficients specific to the perimeter occupied by each segment or other aspects or behavior of the segment, the lateral (e.g., X, Y) position of the droplet as it passes through aperture 364 of charged droplet detector 310 can be extracted. In some cases, the droplet charge can also be extracted, e.g., using the sum signal from all segments, with a small correction for lateral displacement of the droplet from the aperture center measured using the difference signal. Measuring both the droplet's lateral position and the droplet's charge is fundamental and may not require sensor calibration other than knowledge of its shape and the current-to-voltage conversion characteristics of the transimpedance amplifier, although calibration may be used in some examples.

[0049] In some examples, additional sensor layers 361 may be stacked together perpendicular to the axis of movement of the droplet 349 to track the droplet as it passes through the opening of the sensor device 310. While the examples described herein focus on determining or inferring the induced current by measuring the voltage from a transimpedance amplifier, the present disclosure contemplates measuring any suitable value from which the induced current may be determined.

[0050] FIG. 4 shows a side view of charged drop detector 410, which, according to at least some examples, may have components that are different from or the same as those of charged drop management device 110 of FIG. 1, charged drop detector 210A of FIG. 2, or charged drop detector 310 of FIG. 3. While the layers of charged drop detector 410 are shown, additional layers may be implemented in some examples. In some examples, charged drop detector 410 may be or include a printed circuit board that includes printed and / or silkscreened top layer 470 and solder mask layers 469 and 471. Within the printed circuit of charged drop detector 410 are conductive layers 460 and 462 and sensor layer 461 (which is itself a conductive layer), as described above with reference to the components of charged drop detector 310 of FIG. 3. Insulating layers 467 and 468 are disposed between conductive layers 460 and 462 and sensor layer 461 to electrically isolate them from sensor layer 461. All layers define an opening 409 through which charged drop detector 410 passes.

[0051] Insulating layers 467 and 468, conductive layers 460 and 462, and sensor layer 461 may each have any suitable thickness. For example, the insulating layers and / or conductive layers (including the sensor layer) in the charged drop detector may have a thickness of 0.1 mm to 5 mm, e.g., 0.1 mm to 1.0 mm or more, e.g., 0.1 mm to 0.2 mm, 0.2 mm to 0.3 mm, 0.3 mm to 0.4 mm, 0.4 mm to 0.5 mm, 0.5 mm to 0.6 mm, 0.6 mm to 0.7 mm, 0.7 mm to 0.8 mm, 0.8 mm to 0.9 mm, or 10 mm to 12 mm. .9mm, 0.9mm to 1mm, 1mm to 1.1mm, 1.1mm to 1.2mm, 1.2mm to 1.3mm, 1.3mm to 1.4mm, 1.4mm to 1.5mm, 1.5mm to 1.6mm, 1.6mm to 1.7mm, 1.7mm to 1.8mm, 1.8mm to 1.9mm, 1.9mm to 2mm, 2mm to 2.1mm, 2.1mm to 2.2mm, 2.2mm to 2.3 mm, 2.3mm to 2.4mm, 2.4mm to 2.5mm, 2.5mm to 2.6mm, 2.6mm to 2.7mm, 2.7mm to 2.8mm, 2.8mm to 2.9mm, 2.9mm to 3mm, 3mm to 3.1mm, 3.1mm to 3.2mm, 3.2mm to 3.3mm, 3.3mm to 3.4mm, 3.4mm to 3.5mm, 3.5mm to 3.6mm, 3.6mm to 3 The conductive and insulating layers may have thicknesses of 0.7 mm, 3.7 mm to 3.8 mm, 3.8 mm to 3.9 mm, 3.9 mm to 4 mm, 4 mm to 4.1 mm, 4.1 mm to 4.2 mm, 4.2 mm to 4.3 mm, 4.3 mm to 4.4 mm, 4.4 mm to 4.5 mm, 4.5 mm to 4.6 mm, 4.6 mm to 4.7 mm, 4.7 mm to 4.8 mm, 4.8 mm to 4.9 mm, or 4.9 mm to 5 mm. In some cases, the thickness of the conductive and insulating layers may range outside these ranges; in particular, the thickness of the conductive layer may be less than 0.2 mm or less than 0.1 mm. In some examples, the thickness of the conductive or insulating layer may be the same as or greater than the diameter of the droplet; for example, the thickness may be greater than, about 100% of, or greater than the diameter of the droplet.Without limitation, the thickness of the conductive or insulating layer may be about 50%, 100%, 150%, 200%, 250%, 300%, 350%, 400%, 450%, 500%, 550%, 600%, 650%, 700%, 750%, 800%, 850%, 900%, 950%, 1000%, 1500%, 2000%, 3000%, 4000%, or 5000% or more of the diameter of the droplet. In some cases, the ratio of the diameter of the opening to the thickness of the one or more insulating layers may be 0.25 to 4. In some cases, the ratio of the diameter of the opening to the thickness of the one or more conductive layers may be 0.25 to 4. In some cases, the thickness of the conductive layer may be specified by the manufacturer, such as in the case of a charged droplet management device including a printed circuit board, where the thickness of the copper foil or copper plating may be standardized (e.g., a copper layer thickness of about 35 μm, about 70 μm, about 105 μm, or about 140 μm). In some examples, the thickness of each insulating layer is the same, although they may optionally be different. In some examples, the thickness of each conductive layer, including the sensor layer, is the same, although they may optionally be different. In some examples, the thicknesses of the conductive layers and insulating layers are different from each other, although they may optionally be the same.

[0052] 4 shows a total of three electrode layers and a sensor layer, in some examples, additional or fewer conductive layers and / or additional sensor layers may be included. In some examples, layers including conductive layers 460 and 462 and sensor layer 461, as well as other layers, may be arranged non-parallel, such that the layers do not lie along parallel planes, which may be useful for three-dimensional detection of charged droplet position. In some embodiments, sensor layer 461 and conductive layers 460 and 462 are or include a metal, such as, for example, copper. Sensor layer 461 and conductive layers 460 and 462 may have any suitable lateral dimensions, such as 0.5 cm to 5 cm (e.g., 0.5 cm, 0.6 cm, 0.7 cm, 0.8 cm, 0.9 cm, 1.0 cm, 1.1 cm, 1.2 cm, 1.3 cm, 1.4 cm, 1.5 cm, 2 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, 4.5 cm, or 5 cm), but may be implemented with larger or smaller dimensions. In some examples, sensor layer 461, or a component thereof, such as a segment of sensor layer 461, may have a larger lateral dimension than conductive layers 460 and 462 to provide electrical connection to a transimpedance amplifier. For charged drop sensing, conductive layers 460 and 462 may be electrically coupled to a reference potential, such as grounded, while sensor layer 461 is electrically coupled to a charge-sensing circuit or preamplifier, such as a transimpedance amplifier. A transimpedance amplifier integrator circuit may be used to convert the induced current into a detectable voltage output. Insulating layers 467 and 468 may be formed from a suitable dielectric and / or insulating material, such as a laminate (e.g., as used in some printed circuit boards).

[0053] FIG. 5 illustrates a top view of a sensor layer 561 of a charged droplet detector according to at least some embodiments, such as the charged droplet detector of charged droplet management device 110 of FIG. 1 , charged droplet detector 210A of FIG. 2 , charged droplet detector 310 of FIG. 3 , or charged droplet detector 410 of FIG. 4 . Sensor layer 561 defines an opening 564, which in some embodiments may be at least a portion of opening 509 of charged droplet detector 510, and may have a diameter of 2 mm. In some examples, the diameter may be greater or less than 2 mm. Segments 566A, 566B, 566C, and 566D of sensor layer 561 divide the layer into equally sized segments surrounding opening 564, each segment optionally providing an equal portion of the perimeter of opening 564, although such a configuration is not intended to be limiting and any suitable size or configuration of segments may be used. Spacing or insulating regions 507 are disposed between segments 566A, 566B, 566C, and 566D to electrically isolate the segments from one another. Each of segments 566A, 566B, 566C, and 566D is connected to a corresponding transimpedance amplifier 573A, 573B, 573C, and 573D, as described below, which outputs a voltage proportional to the induced current in each of segments 566A, 566B, 566C, and 566D. In some examples, a single transimpedance amplifier or multiple transimpedance amplifiers may be used to determine the total charge on a droplet passing through aperture 564.

[0054] FIG. 6 illustrates a cross-sectional view of a charged droplet detector 510 showing the electrical connections of the sensor layers, according to at least some examples. Charged droplet detector 510 is shown to have the same layers as described with respect to FIG. 4, including three conductive layers 560, 561, and 562 separated by two insulating layers 567 and 568. In some embodiments, the total thickness of charged droplet detector 510 is approximately 1 mm, but may be greater or less than 1 mm. In some embodiments, the layers may all have a thickness of 200 micrometers (0.008 inches). In some embodiments, the total thickness may be approximately 2 mm. Charged droplet detector 510 may be mounted between a source and target of charged droplets such that the droplets travel upward through aperture 509. Mounts for positioning the detector in X, Y, and Z above the charged droplet source and aligning aperture 509 with the transducer axis are not shown.

[0055] For droplet sensing, the two conductive layers 560 and 562, as well as any other layers such as the sensor layer 561, may be electrically coupled to or biased against a reference voltage, such as a high voltage supply, and each of the segments 566A, 566B, 566C, and 566D of the sensor layer 561 may be electrically coupled to a circuit element, such as a transimpedance amplifier, to generate a signal, such as an induced current or voltage. Each of the conductive layers 560 and 562 and the sensor layer 561 may optionally be biased to a high voltage to generate a charge on the droplet as it passes through the opening 564, such as in the case of a droplet generator that does not generate charged droplets. In some examples, the high voltage may be applied to a target using a wire mesh grid or directly to an open-port probe. As the droplet passes through the opening 564, the electric field resulting from the voltage bias may exert a force on the charged droplet, which may accelerate, decelerate, or deflect the droplet in undesirable ways. Therefore, a uniform electric field along the droplet trajectory, such as a uniform electric field along the axis between the droplet generator and the target, is advantageous. In some examples, one or more of conductive layers 560 and 562, or any other conductive layer, may be floating and / or at a reference (e.g., ground) voltage. The examples provided and described herein may include a fluid reservoir biased to a high potential, while charged droplet detector 510 is at a reference or ground potential. It will be understood that other implementations, such as biasing charged droplet detector 510 to a high voltage, may be used to induce an electric charge on ejected droplets and may be suitable for use in the systems and methods described herein.

[0056] In some examples, although only one transimpedance amplifier 573 is shown in FIG. 6 , each segment 566A, 566B, 566C, and 566D can be associated with a transimpedance amplifier, which may include one or more transimpedance amplifiers. In the example shown in FIG. 5 , four transimpedance amplifiers 573A, 573B, 573C, and 573D are shown, each coupled to a corresponding segment of the sensor layer 561. In some examples, the sensor layer 561 can be composed of any number of segments, and each segment may be coupled to a corresponding transimpedance amplifier or other circuit element. In some embodiments, the transimpedance unit 573 can include a Peltier-cooled input transistor with feedback components such as a Cf of 0.5 pF and an Rf of 1 gigaohm. The integrator circuit of the transimpedance unit 573 converts the current in the segment of the sensor layer 561 induced by the charged droplet 549 into a voltage output.

[0057] FIG. 7 shows an exploded view of the layers of a charged droplet controller 710, according to at least some examples. Charged droplet controller 710 may correspond to one implementation of charged droplet management device 110 of FIG. 1. Charged droplet controller 710 includes a first conductive layer 760, a first support or insulating layer 761, a second conductive layer 762, and a second support or insulating layer 763. The conductive layers of the charged droplet controller, which may be segmented, may be referred to herein as conductivity control layers. When charged droplet 749 passes through an opening in charged droplet controller 710, e.g., an opening including or encompassing openings 764, 765, 766, and 767, an electric field may be applied between opposing segments of conductive layer 760 or 762, e.g., between segments 768A and 768B of first conductive layer 760 and between segments 768C and 768D of second conductive layer 762.

[0058] An electric field can be applied by holding opposing segments within a conductive layer at different relative voltages. As shown, segments 768A and 768B of first conductive layer 760 generate an electric field along the X direction, inducing deflection of charged droplets 749 along the X direction, while segments 768C and 768D of second conductive layer 762 generate an electric field along the Y direction, inducing deflection of charged droplets 749 along the Y direction. While FIG. 7 shows segments 768A, 768B, 768C, and 768D as being located on separate conductive layers 762, in some charged droplet controllers, the segments for modifying the trajectories of charged droplets may all be located on the same plane or layer. Furthermore, while four segments are shown, any suitable number of segments can be used, and the voltages between the various segments can be adjusted to generate the appropriate electric fields for modifying the trajectories of charged droplets as they pass through the aperture. 7 shows two support or insulating layers 761 and 763, any suitable number of support or insulating layers may be used. For example, some configurations may not use any support or insulating layers (e.g., where the conductive layer provides its own support structure). In other examples, only one support or insulating layer may be used (e.g., where the conductive layer segments are all in the same plane or layer and are supported by a single support or insulating layer).

[0059] Optionally, additional conductive layers may be used in the charged droplet controller beyond those used to adjust the trajectory of the charged droplets as they pass through the aperture. In some examples, one or more ground or reference conductive layers, similar to conductive layers 362 and 360 shown in FIG. 3 , may be disposed above and / or below the primary conductive layer containing the segments and used to modify the trajectory of the charged droplets. The use of such ground or reference conductive layers may be useful in limiting the extent of the electric field generated by the segmented conductive layer from extending significantly beyond the aperture. In some examples, all components of the charged droplet controller may be biased to a relative potential higher or lower than ground and / or with respect to the droplet generator or target potential. The voltage applied to each segment may be controlled using one or more voltage controllers or voltage generators, either integrated as part of the charged droplet controller 710 or provided by external circuitry.

[0060] 7 as planar, while insulating layer 761 is shown with a particular thickness, any suitable thickness dimensions may be used. For example, the insulating and / or conductive layers in the charged droplet controller may be 0.1 mm to 5 mm, e.g., 0.1 mm to 1.0 mm or more, e.g., 0.1 mm to 0.2 mm, 0.2 mm to 0.3 mm, 0.3 mm to 0.4 mm, 0.4 mm to 0.5 mm, 0.5 mm to 0.6 mm, 0.6 mm to 0.7 mm, 0.7 mm to 0.8 mm, 0.8 mm to 0.9 mm, 0.9 mm to 10 mm, 0.9 mm to 11 mm, 0.9 mm to 12 mm, 0.9 mm to 13 mm, 0.9 mm to 14 mm, 0.9 mm to 15 mm, 0.9 mm to 16 mm, 0.9 mm to 17 mm, 0.9 mm to 18 mm, 0.9 mm to 19 ... .9mm to 1mm, 1mm to 1.1mm, 1.1mm to 1.2mm, 1.2mm to 1.3mm, 1.3mm to 1.4mm, 1.4mm to 1.5mm, 1.5mm to 1.6mm, 1.6mm to 1.7mm, 1.7mm to 1.8mm, 1.8mm to 1.9mm, 1.9mm to 2mm, 2mm to 2.1mm, 2.1mm to 2.2mm, 2.2mm to 2.3mm, 2 .3mm to 2.4mm, 2.4mm to 2.5mm, 2.5mm to 2.6mm, 2.6mm to 2.7mm, 2.7mm to 2.8mm, 2.8mm to 2.9mm, 2.9mm to 3mm, 3mm to 3.1mm, 3.1mm to 3.2mm, 3.2mm to 3.3mm, 3.3mm to 3.4mm, 3.4mm to 3.5mm, 3.5mm to 3.6mm, 3.6mm to 3.7 The conductive and insulating layers may have thicknesses of 3.7 mm to 3.8 mm, 3.8 mm to 3.9 mm, 3.9 mm to 4 mm, 4 mm to 4.1 mm, 4.1 mm to 4.2 mm, 4.2 mm to 4.3 mm, 4.3 mm to 4.4 mm, 4.4 mm to 4.5 mm, 4.5 mm to 4.6 mm, 4.6 mm to 4.7 mm, 4.7 mm to 4.8 mm, 4.8 mm to 4.9 mm, or 4.9 mm to 5 mm. In some cases, the thicknesses of the conductive and insulating layers may range outside these ranges; in particular, the conductive layer thickness may be less than 0.2 mm or less than 0.1 mm. In some cases, the ratio of the diameter of the opening to the thickness of the insulating layer(s) may be 0.25 to 4. In some cases, the ratio of the diameter of the opening to the thickness of the conductive layer(s) may be 0.25 to 4.In some cases, the thickness of the conductive layer may be specified by the manufacturer, such as in the case of a charged droplet management device including a printed circuit board, where the copper foil or copper plating may have a standardized thickness (e.g., a copper layer thickness of about 35 μm, about 70 μm, about 105 μm, or about 140 μm). In some examples, the thickness of each insulating layer is the same, but they may be different in some cases. In some examples, the thickness of each conductive layer (if multiple conductive layers are present) is the same, but they may be different in some cases. In some examples, the thicknesses of the conductive and insulating layers are different from each other, but they may be the same in some cases. In some examples, a thicker conductive layer may be useful to impart a strong trajectory change to the charged droplets, since a thicker conductive layer increases the time the charged droplets interact with the electric field. Such cases may be considered as a conductive layer having a cylindrical opening, although in some examples it is segmented.

[0061] The strength of the electric field generated between segments 768A and 768B of the first conductive layer 760 and segments 768C and 768D of the second conductive layer 762 can be determined, for example, by the relative voltage of each segment or the voltage difference between opposing segments. In some examples, any suitable voltage difference can be applied between opposing segments, although very high voltages can generate an electric field sufficient to break down the air and cause electrostatic discharge, which is desirable to avoid. In some examples, the relative voltage between different segments can be from 0 V to 500 V or more, depending on the geometry of the segments. Examples of relative voltages between different segments can be 0 V to 25 V, 0 V to 50 V, 0 V to 75 V, 0 V to 100 V, 0 V to 125 V, 0 V to 150 V, 0 V to 175 V, 0 V to 200 V, 0 V to 225 V, 0 V to 250 V, 0 V to 275 V, 0 V to 300 V, 0 V to 325 V, 0 V to 350 V, 0 V to 375 V, 0 V to 400 V, 0 V to 425 V, 0 V to 450 V, 0 V to 475 V, or 0 V to 500 V. It will be appreciated that the greater the voltage difference between the segments, the stronger the electric field and the greater the orbital adjustment.

[0062] For example, feedback mechanisms may be implemented in the systems, techniques, devices, and methods described herein to enable the voltages applied to different segments of the charged drop controller to be determined and selected based on the required trajectory adjustment. For example, by measuring the position of the charged drop, such as with a charged drop detector described herein, and using fixed or known geometric parameters of the system and target, the voltages required to apply to different segments within the charged drop controller can be determined. For example, if the openings of the charged drop detector and charged drop controller are aligned with the ejection axis of the charged drop generator and further aligned with the target, drops passing through the exact center of the openings of the charged drop detector and charged drop controller will not require any trajectory adjustment, and therefore the voltages applied to the segments of the charged drop controller can be selected to produce very small or zero electric fields so as not to impose any trajectory deviation. In another example, droplets that are misdirected from the center of the aperture and pass closer to one segment than another have their location identified by the charged droplet detector, which allows for the determination and selection of appropriate voltages to apply to segments of the charged droplet controller to correct the trajectory of the charged droplet so that it reaches the target on axis. In some examples, a lookup table or adapted analytical solution can be used to generate the voltages to apply to different segments of the charged droplet controller based on the position of the charged droplet determined in the charged droplet detector.

[0063] FIG. 8 illustrates a side view of charged droplet controller 810, which, according to at least some examples, may be different from or the same as components of charged droplet management device 110 of FIG. 1, charged droplet controller 210B of FIG. 2, or charged droplet controller 710 of FIG. 7. While layers of charged droplet controller 810 are shown, additional layers may be implemented in some examples. In some examples, charged droplet controller 810 may be or include a printed circuit board including printed and / or silkscreened top layer 870 and solder mask layers 869 and 871. Within the printed circuit of charged droplet controller 810 are conductive layers 860 and 862, as described above with reference to the components of charged droplet controller 710 of FIG. 7. Insulating layers 861 and 863 are disposed between conductive layers 860 and 862 to support and / or electrically insulate conductive layers 860 and 862 from one another. All layers define an opening 809 through which the charged droplet detector 810 passes. Insulating layers 861 and 863 may have a thickness between 0.1 millimeter and 1.0 millimeter in some examples. While charged droplet controller 810 in FIG. 8 shows two total conductive layers and two total insulating layers, other examples may include more or fewer conductive and / or insulating layers. In some examples, layers including conductive layers 860 and 862 and insulating layers 861 and 863, as well as other layers, may be arranged non-parallel, such that the layers do not lie along parallel planes. In some embodiments, conductive layers 860 and 862 are or include, for example, copper or gold. Conductive layers 860 and 862 may have any suitable lateral dimensions, such as 0.5 cm to 5 cm (e.g., 0.5 cm, 0.6 cm, 0.7 cm, 0.8 cm, 0.9 cm, 1.0 cm, 1.1 cm, 1.2 cm, 1.3 cm, 1.4 cm, 1.5 cm, 2 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, 4.5 cm, or 5 cm), but may be implemented with larger or smaller dimensions.In some examples, conductive layers 860 and 862, or components thereof, such as segments of conductive layers 860 and 862, may have larger lateral dimensions than insulating layers 861 and 863 to provide electrical connections to one or more voltage controllers. Insulating layers 861 and 863 may be formed from a suitable dielectric and / or insulating material, such as a laminate (e.g., as used in some printed circuit boards).

[0064] FIG. 9 shows a top view of conductive layer 960 of charged droplet controller 910, which may be the same as or different from charged droplet controller 110 of FIG. 1 , charged droplet controller 210B of FIG. 2 , charged droplet controller 710 of FIG. 7 , or charged droplet controller 810 of FIG. 8 , according to at least some examples. Conductive layer 960 defines opening 965, which is at least a portion of opening 909 of charged droplet controller 910 and may have a diameter of 2 mm in some embodiments. In some examples, the diameter may be greater or less than 2 mm. Segments 968A, 968B, 968C, and 968D of conductive layer 960 divide the layer into equally sized segments surrounding opening 965, with each segment optionally providing an equal portion of the perimeter of opening 965. Spacing or insulating regions 907 are disposed between segments 968A, 968B, 968C, and 968D to electrically isolate the segments from one another. Each of segments 968A, 968B, 968C, and 968D is connected to a corresponding voltage controller 974A, 974B, 974C, and 974D, as described below, to generate an electric field of desired or predetermined magnitude and direction at opening 965 and modify the trajectory of charged droplets 949 passing through opening 965. In some examples, a single voltage controller or multiple voltage controllers may be used to apply voltages between different segments of conductive layer 960. In some cases, a single voltage controller may be connected between opposing segments to set a voltage difference between the opposing segments. For example, voltage controllers 974A and 974C may be the same voltage controller for setting a voltage difference between segments 968A and 968C, or voltage controllers 974B and 974D may be the same voltage controller for setting a voltage difference between segments 968B and 968D. In some examples, although only one voltage controller 974 is shown in FIG. 10, each segment 968A, 968B, 968C, and 968D may be associated with a voltage controller, which may possibly include one or more voltage controllers.In the example shown in FIG. 9, four transimpedance amplifiers 974A, 974B, 974C, 974D are shown, each coupled to a corresponding segment of conductive layer 960.

[0065] FIG. 10 shows a cross-sectional view of a charged droplet controller 910 showing the electrical connections of the conductive layers, according to at least some examples. The charged droplet controller 910 is shown having different numbers and configurations of layers as described with respect to FIG. 8, including one conductive layer 960 and one insulating layer 961. In some embodiments, the total thickness of the charged droplet controller 910 is approximately 0.4 mm, but may be greater or less than 0.4 mm. In some embodiments, the layers may all have a thickness of 200 micrometers (0.008 inches). In some embodiments, the total thickness may be approximately 0.8 mm. The charged droplet controller 910 may be mounted between a source and target of charged droplets such that the droplets travel upward through an opening 909. Mounts for positioning the controller in X, Y, and Z above the charged droplet source and aligning the opening 909 with the transducer axis are not shown.

[0066] For droplet control, a voltage difference applied between opposing segments 968A and 968C can be used to adjust the deflection of charged droplets along the Y direction, and a voltage difference applied between opposing segments 968B and 968D can be used to adjust the deflection of charged droplets along the X direction. The voltages applied to the segments of conductive layer 960 may be biased above or below ground potential to establish an overall floating potential relative to charged droplet controller 910, which can be used to accelerate, decelerate, or maintain the relative velocity of charged droplets approaching or leaving charged droplet controller 910. As the droplets pass through aperture 965, the electric fields generated by the voltages applied to the different segments can exert forces on the charged droplets, which can accelerate, decelerate, and deflect the trajectory of charged droplets 949 in a controlled manner.

[0067] Figures 11, 12, and 13 show charts illustrating values ​​corresponding to induced currents in different segments as charged droplets pass through the aperture of a charged droplet detector. Figure 11 illustrates differential currents flowing through opposing segments, which will be described in more detail below. Figure 12 illustrates chart 1279 illustrating currents from a segment of a sensor layer of a charged droplet detector over time due to a charged droplet moving through the aperture of the charged droplet detector, according to at least some examples. Each of the illustrated data sets 1282, 1281, and 1280 represents currents measured in a segment as a charged droplet is ejected from a fluid reservoir through the aperture toward a target location. As shown, data sets 1282, 1281, and 1280 represent currents in the segment at different lateral offsets of the charged droplet from the segment of the sensor layer. For example, data set 1280 may represent a droplet passing through the center of the aperture, while data set 1282 is laterally offset on the side of the sensor layer closer to the segment, and data set 1281 is laterally offset away from the segment on the opposite side of the aperture from the location associated with data set 1282. As shown, the larger current represented by data set 1282 represents a charged droplet located closer to the segment than the smaller current represented by data set 1281. On the left side of FIG. 12, each data set 1280, 1281, 1282 represents an initial induced current at t0 indicating that a charged droplet is not within the aperture. As the droplet passes through the sensor layer of the charged droplet detector at t1, the current represented by data sets 1280, 1281, and 1282 passes through the initial reference and reverses as the induced current direction reverses until t2, when the droplet exits the aperture. Similarly, Figure 13 shows the output voltages from the four transimpedance amplifiers, which vary in amplitude based on the variation in the segment current values ​​over time as the droplet passes through the aperture of the charged droplet detector.For example, the measured voltages depicted in chart 1383 of FIG. 13 indicate that the corresponding droplets passed through the charged droplet detector closer to the segments associated with data sets 1385 and 1386 than to the segments associated with data sets 1384 and 1387 (as evidenced by the greater voltage fluctuations).

[0068] 11 illustrates a chart 1174 showing differential current from opposing segments of a sensor layer of a charged droplet detector for different charged droplet displacement positions along an axis between a droplet source and a droplet target destination, according to at least some examples. In chart 1174, the horizontal axis is time, which can be correlated to the vertical position (Z position) of the charged droplet when the signal is measured, while the differential current is shown on the vertical axis. Different data sets representing different signals are shown in chart 1174 corresponding to the difference in measured current between opposing segments located on opposite sides of the aperture as the charged droplet passes through the aperture.

[0069] The first data set 1175 of the chart shows the difference in output voltage between opposing segments, such as segments 366B and 366D in FIG. 3 or segments 566B and 566D in FIG. 5, for a droplet whose trajectory is vertical but offset laterally from the center of the aperture toward one of the segments. A corresponding series of curves from the measured current difference between segments 366A and 366C in FIG. 3 or segments 566A and 566C in FIG. 5 would also provide information about the position of the droplet along a second direction relative to the aperture center (e.g., along the Y-axis shown in FIG. 5) as the droplet passes through the center of the aperture. If the droplet passed through the center of the aperture in both directions (e.g., the X- and Y-directions shown in FIG. 5), all differential curves would be substantially flat and point to an output of 0V. The output from each segment may be weighted or normalized with respect to the sum of the currents flowing through all segments (essentially normalizing and removing the droplet charge from the differential measurement), or may be normalized using a weighting factor representative of the area of ​​the segment or the percentage of the aperture perimeter occupied by the segment. In some examples, the output may be normalized by dividing each output by the sum of all outputs from each sensor. In some examples, the total signal from all segments due to a droplet passing through the device has the shape of a bipolar pulse. The magnitude of this summed signal may serve as an appropriate normalization factor for the differential current. The polarity of the droplet charge may be extracted by noting the phase of the bipolar pulse obtained from the sum of the sensor signals. A second data set 1176 shows the difference in measured current between segments for a droplet trajectory offset from the central axis of the aperture toward the second segment by a first amount in the opposite direction to the first data set 1175. The third data set 1177 shows the difference in measured current between segments in a droplet that is offset along a first direction (e.g., along the X-axis shown in FIG. 5) toward the first of the segments by a second amount that is less than the first amount, thereby resulting in a smaller difference in measured current between opposing segments.A fourth data set 1178 of chart 1174 shows the difference in measured current between segments for droplets offset from the central axis of the aperture by a second amount toward the second segment in the opposite direction to the third data set 1177. The differential current from the segments, when normalized as described above by the summed sensor signals, and together with knowledge of the droplet charge polarity obtained from the summed sensor signals, can be used to determine the lateral offset of the droplet trajectory along the first direction (e.g., along the X-axis shown in FIGS. 3 and 5). A similar analysis of the differential current from additional segments (e.g., perpendicular segments) can enable the determination of the lateral offset of the droplet trajectory along the Y-axis in FIGS. 3 and 5. The lateral offset along the X-axis and Y-axis may be used to generate weights that identify the droplet's position, such as a droplet position weighting map, where the relative position of the droplet corresponds to the weighting of the current from opposing segments.

[0070] The output voltage and / or differential current can be useful in identifying the location of the charged droplet as well as the velocity of the charged droplet. In some examples, the sum of all output voltages or currents can be used to determine the droplet charge and velocity (e.g., using sum 1494 in Figure 14). In chart 1174, the horizontal axis is time, which can be correlated to the vertical position (Z position) of the charged droplet as the signal is measured, while the differential current is shown on the vertical axis. Velocity can be determined, for example, based on the time it takes to cross the charged droplet detector. Because the droplets pass through the device at an essentially constant velocity, the positions shown in charts 1174 and 1279 are related to time by the droplet velocity. In charts 1174 and 1279, each of the curves has three distinct features: a peak, a minimum, and a zero crossing that occurs approximately halfway between the peak and minimum. The respective times associated with each of these features are T peak , T min , T zerocrossing The time at which acoustic energy is delivered to the fluid surface to generate droplets can be defined as T0. The droplets form at time T zerocrossing(This is when the droplet reaches the shortest distance to each segment and the current becomes zero.) Consider the height of the sensor layer above the fluid in the well (as will generally be the case), and define this height as H sensor One measure of droplet velocity is called H sensor / (T zerocrossing This formula calculates the velocity based on the time it takes for the droplet to reach the sensor layer from the fluid surface, since the height of the sensor layer above the fluid surface is known.

[0071] In some instances, the droplet velocity is T peak and T min This difference can be related to the droplet velocity and the distance between the conductive layers (e.g., conductive layers 362 and 360 in FIG. 3), referred to herein as distance d. For an exemplary conductive layer geometry, time T peak -T min =0.71*d / v droplet where v droplet is the "instantaneous" velocity of the droplet as it passes through the sensor layer. Therefore, the instantaneous velocity is v droplet =0.71*d / |T peak -T min The coefficient of 0.71 was obtained from device modeling, but is strictly due to the shape and is independent of the droplet charge, volume, or other factors, so other coefficients can be used for other shapes.

[0072] FIG. 14 illustrates a chart 1488 showing output voltage signals 1489, 1490, 1491, and 1492, as well as a sum 1494 of all output voltage signals received from the transimpedance amplifiers associated with the four segments of the sensor layer, as shown and described with respect to FIG. 5 above. According to at least some examples, the output voltage signals can be used to determine a position 1496 of a droplet moving through an aperture in the sensor device. Using the output signals of chart 1488 and performing the calculations described herein, an estimated XY position 1496 of the droplet is determined and is shown in FIG. 15. The estimated XY position 1496 of the droplet corresponds to the predicted position (predicted using the output signals described herein) at which the droplet will pass through the aperture, while the stage position XY position 1495 refers to a transducer axis defined by the position of the stage on which the transducer is positioned, such as transducer axis 118 of FIG. 1. That is, stage position XY location 1495 is where the droplet is expected to pass through the aperture, assuming the droplet's trajectory is aligned along the axis of the acoustic transducer. As shown in Figure 15, estimated XY location 1496 and stage position XY location 1495 coincide, thus validating the use of induced currents to predict droplet position as described herein. As described above, induced currents in the sensor layer segments can be used to determine position based on the relative sizes of the peaks in output voltage signals 1489, 1490, 1491, and 1492.

[0073] FIG. 16 shows a chart 1600 providing output voltage signals 1601, 1602, 1603, and 1604, as well as a sum 1609 of all output voltage signals corresponding to a main droplet 1608 and satellite droplets 1606 moving through an aperture, according to at least some embodiments. Satellite droplets 1606 are undesired secondary droplets that may be ejected from a fluid during a given ejection and may be generated if the device is not properly adjusted or if excessive force is applied when main droplet 1608 is generated. The resulting signals from the four segments of the sensor layer are shown as output from the transimpedance amplifier in FIG. 16, and the estimated XY positions of main droplet 1608 and satellite droplets 1606 are shown in FIG. 17, along with stage position 1607. The positions of main droplet 1608 and satellite droplets 1606 are determined from the induced currents in the indicated segments of the sensor layer, identifying peaks indicative of the positions of main droplet 1608 and satellite droplets 1606. The location of satellite droplets 1606 can be determined based on relative amplitudes, for example, to distinguish between main droplet 1608 and satellite droplets 1606. For example, in FIG. 16 , satellite droplet 1606 is identifiable at T2, while main droplet 1608 is at T1 and clearly identifiable based on the difference in peaks in the data set representing total 1609. In some embodiments, identifying satellite droplets can be useful in determining whether ejection parameters (e.g., transducer parameters) need to be adjusted. For example, a method can include determining that a satellite droplet was ejected in a particular ejection based on measurements of values ​​corresponding to induced currents described herein. Based on this determination, it can be determined that transducer parameters need to be adjusted to prevent further ejection of satellite droplets. Accordingly, the transducer parameters can be adjusted (e.g., by reducing the amplitude or frequency of the acoustic signal) for the next ejection. These steps can be repeated as many times as necessary to provide iterative fine-tuning of the ejection and prevent or at least reduce the ejection of satellite droplets.

[0074] 18 shows a flowchart illustrating a process for detecting charged droplets from a droplet generator, according to at least some examples. Any suitable computing system or computing systems may be used to perform aspects of the methods described herein. For example, FIG. 25 shows an example computing device 2500 that may be at least part of a computing system for performing operations or methods described herein.

[0075] At block 1802, method 1800 includes disposing a charged droplet detector between the droplet generator and the target, as shown in Figures 1 and 2. The detector may be a component of charged droplet management device 110 of Figure 1, charged droplet detector 210A of Figure 2, charged droplet detector 310 of Figure 3, charged droplet detector 410 of Figure 4, or charged droplet detector 510 of Figure 6, according to at least some examples. The charged droplet detector may be positioned to have an opening aligned with the ejection axis of the droplet generator (e.g., the transducer axis of an acoustic droplet ejection system).

[0076] At block 1804, method 1800 includes directing charged droplets from the droplet generator toward the target through an opening in the charged droplet detector. The charged droplets may be propelled by a droplet generator, for example, as described with respect to FIG. 1.

[0077] At block 1806, method 1800 includes analyzing voltage signals generated by the charged droplet detector to determine the position and / or velocity of the droplet. The voltage signals may be output by transimpedance amplifiers connected to each of the segments of the sensor layer. The voltage signals may correspond to induced currents in each segment resulting from the charged droplet passing through the aperture. As described herein, the position of the droplet may be determined based on a weighting of the voltage signals from the segments of the sensor layer.

[0078] Figure 19 shows a top view of a conductive layer 1960 of a charged droplet controller, which, according to at least some embodiments, may be the same as or different from charged droplet management device 110 of Figure 1, charged droplet controller 210B of Figure 2, charged droplet controller 710 of Figure 7, charged droplet controller 810 of Figure 8, or the charged droplet detector of charged droplet controller 810 of Figure 8. Figure 19 shows voltages V1, V2, V3, and V4 applied to segments 1968A, 1968B, 1968C, and 1968D of conductive layer 1960, respectively.

[0079] Figures 20, 21, and 22 show the relative positions of a charged droplet at a first Z position (+) and a second Z position (O) as measured by two charged droplet detectors on opposite sides of the charged droplet controller, with voltages applied to segments 1968A, 1968B, 1968C, and 1968D of the charged droplet controller as in Figure 19. In Figures 20, 21, and 22, the first Z position 2095 (+) of the charged droplet is determined to be offset along both the X and Y directions from the center 2019 of the aperture.

[0080] Figure 20 shows a configuration in which the voltage difference applied between segments 1968A and 1968C is zero (V1-V3=0V) and the voltage difference applied between segments 1968B and 1968D is zero (V2-V4=0V), indicating that the charged droplet controller is not deflecting the charged droplet. A second Z position 2096(O) of the charged droplet is also shown in Figure 20 as being offset from center 2019.

[0081] Figure 21 shows a configuration in which the voltage difference applied between segments 1968A and 1968C is zero (V1-V3=0V), but the voltage difference applied between segments 1968B and 1968D is 200V (V2-V4=200V), indicating that the charged droplet controller is deflecting the charged droplet along the X direction but not along the Y direction. The second Z position 2097(O) of the charged droplet is shown in Figure 21 to still be offset from center 2019, but to a lesser extent in the X direction than in Figure 20, indicating that the adjustments to the trajectory of the charged droplet applied by the charged droplet controller provide some correction to the trajectory, but that further correction may provide further improvement.

[0082] FIG. 22 shows a configuration in which the voltage difference applied between segments 1968A and 1968C is 400 V (V1-V3=400 V) and the voltage difference applied between segments 1968B and 1968D is 400 V (V2-V4=400 V), indicating that the charged droplet controller deflects the charged droplets along the X and Y directions even more than the X-direction deflection in FIG. 21. The position 2098(O) of the charged droplet on the substrate under such voltage conditions is corrected to be very close to the center 2019, as shown in FIG. 22. It will be understood that the voltages applied to the various segments referred to above with respect to FIGS. 20, 21, and 22 are merely exemplary and are not intended to be limiting. Any suitable voltage or voltage difference may be used to adjust the trajectory of the charged droplets, and such voltage or voltage difference may be determined by the geometry of the system, the position and / or velocity of the charged droplets, and / or the desired change in trajectory (including magnitude and direction).

[0083] 23 shows a flowchart illustrating a process for controlling charged droplets ejected from a droplet generator, according to at least some examples. Any suitable computing system or computing systems may be used to perform aspects of the methods described herein. For example, FIG. 25 shows an example computing device 2500 that may be at least part of a computing system for performing operations or methods described herein.

[0084] At block 2302, method 2300 includes disposing a charged droplet controller between the droplet generator and the target, as shown in Figures 1 and 2. The charged droplet controller may be, according to at least some examples, a component of charged droplet management device 110 of Figure 1, charged droplet controller 210B of Figure 2, charged droplet controller 710 of Figure 7, charged droplet controller 810 of Figure 8, or charged droplet controller 910 of Figure 10. The charged droplet controller may be positioned to have an opening aligned with the ejection axis of the droplet generator (e.g., the transducer axis of an acoustic droplet ejection system).

[0085] At block 2304, the method 2300 includes directing the charged droplets from the droplet generator toward the target through an opening in the charged droplet controller. The charged droplets may be propelled by a droplet generator such as described with respect to FIG.

[0086] At block 2306, method 2300 includes determining and applying a voltage to one or more conductive layer segments of the charged droplet controller to modify the droplet trajectory. The voltage may be generated automatically or may be generated using feedback of the velocity or position of the charged droplet as determined by, for example, a charged droplet detector. In other examples, a voltage may be empirically determined and applied to control the trajectory of additional droplets via user input, for example, to adjust or optimize the droplet trajectory for reaching a target or to improve arrival.

[0087] 24 shows a flowchart illustrating a process for detecting and controlling charged droplets ejected from a droplet generator using a feedback scheme, according to at least some examples. Any suitable computing system or computing systems may be used to perform aspects of the methods described herein. For example, FIG. 25 shows an example computing device 2500 that may be at least part of a computing system for performing the operations or methods described herein.

[0088] In block 2402, method 2400 includes disposing a charged droplet detector between the droplet generator and the charged droplet controller, as shown in Figure 2. The charged droplet detector may be a component of charged droplet management device 110 of Figure 1, charged droplet detector 210A of Figure 2, charged liquid detector 310 of Figure 3, charged droplet detector 410 of Figure 4, or charged droplet detector 510 of Figure 6, according to at least some examples. The charged droplet controller may be a component of charged droplet management device 110 of Figure 1, charged droplet controller 210B of Figure 2, charged liquid controller 710 of Figure 7, charged droplet controller 810 of Figure 8, or charged droplet controller 910 of Figure 10, according to at least some examples. The charged droplet detector and the charged droplet controller may be arranged to have openings aligned with each other and / or aligned with the ejection axis of the droplet generator (e.g., aligned with the transducer axis of an acoustic droplet ejection system).

[0089] At block 2404, the method 2400 includes directing charged droplets from the droplet generator through an opening in a charged droplet detector and a charged droplet controller. The charged droplets may be propelled by a droplet generator such as described with respect to FIG. 1.

[0090] At block 2406, method 2400 includes analyzing voltage signals generated by the charged droplet detector to determine the position and / or velocity of the droplet. The voltage signals may be output by transimpedance amplifiers connected to each of the segments of the sensor layer of the charged droplet detector. The voltage signals may correspond to induced currents in each segment resulting from the charged droplet passing through the aperture. As described herein, the position of the droplet may be determined based on a weighting of the voltage signals from the segments of the sensor layer. In some examples, the voltage waveform from the transimpedance amplifier may be analyzed by a signal processing component to extract the position and / or velocity of the charged droplet in the charged droplet detector.

[0091] At block 2410, method 2400 includes determining and applying a voltage to one or more conductive layer segments of the charged droplet controller to modify the droplet trajectory. The voltage is determined using the velocity or position of the charged droplet from the signal processing component, and may be determined using a lookup table or analytical function, such as with one or more coordinates (e.g., X and Y) of the charged droplet as input, and the voltage applied to the segment (or voltage difference for application to opposing segments) is determined as the output applied to the conductive layer segment.

[0092] 25 shows a block diagram of an example computing device 2500. Computing device 2500 may be any of the computers described herein, including a computing device that performs method 1800 and receives signals from one or more transimpedance amplifiers, e.g., method 2300, method 2400, other methods described herein, or various aspects or portions of such methods. Computing device 2500 may be or include, for example, an all-in-one computer, a laptop computer, a desktop computer, a tablet, a server, or other electronic device.

[0093] Computing device 2500 may include a processor 2540 coupled to other hardware via a bus 2505. Memory 2510 may include any suitable tangible (and non-transitory) computer-readable medium, such as RAM, ROM, EEPROM, etc., and may embody program components (e.g., program code 2515) that configure the operation of computing device 2500. Memory 2510 may store program code 2515, program data 2517, or both. In some examples, computing device 2500 may include input / output ("I / O") interface components 2525 (e.g., for interfacing with a display 2545, keyboard, mouse, etc.) and additional storage 2530.

[0094] Computing device 2500 executes program code 2515 that configures processor 2540 to perform one or more of the operations described herein. Examples of program code 2515 include, in various examples, the logic of the flowcharts described with respect to Figures 18, 23, and 24 above. Program code 2515 may reside in memory 2510 or any suitable computer-readable medium and may be executed by processor 2540 or any other suitable processor.

[0095] Computing device 2500 may generate or receive program data 2517 by executing program code 2515. For example, sensor data, trip counters, authenticated messages, trip flags, and other data described herein are all examples of program data 2517 that may be used by computing device 2500 during execution of program code 2515.

[0096] The computing device 2500 may include a network component 2520. The network component 2520 may represent one or more of any components that facilitate a network connection. In some examples, the network component 2520 may facilitate a wireless connection and may include a wireless interface such as IEEE 802.11, BLUETOOTH, or a wireless interface for accessing a cellular network (e.g., a transceiver / antenna for accessing a CDMA, GSM, UMTS, or other mobile communications network). In other examples, the network component 2520 may be wired and may include an interface such as Ethernet, USB, or IEEE 1394.

[0097] 25 depicts a computing device 2500 with a processor 2540, a system may include any number of computing devices and any number of processors. For example, multiple computing devices or multiple processors may be distributed over a wired or wireless network (e.g., a wide area network, a local area network, or the Internet). Multiple computing devices or multiple processors may perform any of the steps of the present disclosure individually or in cooperation with each other.

[0098] Aspects of the present invention can be further understood by reference to the following non-limiting examples. [Example]

[0099] Example 1: Charged Droplet Ejection, Detection, and Control System Figure 26 provides an overview of one example of a charged droplet ejection, detection, and control system 2600, according to some examples. System 2600 may include components described elsewhere in this disclosure, including one or more droplet generators, such as droplet generator 101 described with reference to Figures 1 and 2, one or more charged droplet management devices, such as charged droplet management device 110 of Figure 1, one or more charged droplet detectors, such as charged droplet detector 210A of Figure 2, charged droplet detector 310 of Figure 3, charged droplet detector 410 of Figure 4, or charged droplet detector 510 of Figure 6, one or more charged droplet controllers, such as charged droplet controller 210B of Figure 2, charged droplet controller 710 of Figure 7, charged droplet controller 810 of Figure 8, or charged droplet controller 910 of Figure 10, and one or more computing devices, such as computing device 2500.

[0100] 26, system 2600 includes a charged droplet control and detection system 2605. Charged droplet control and detection system 2605 may include physical hardware including, for example, a droplet generator and a charged droplet management device. As described above with reference to FIG. 1, the droplet generator of the charged droplet control and detection system may include an acoustic droplet ejection system that employs tone burst excitation 2610 to drive an acoustic generator to eject droplets.

[0101] Charged droplet control detection system 2605 may be in data and / or control communication with data acquisition system 2615, which may include one or more computing devices according to examples described herein. As shown, a digital signal associated with tone burst excitation 2610 may be communicated to an external interrupt 2620 of data acquisition system 2615, which may enable data acquisition system 2615 to determine the time when droplets are generated by charged droplet control detection system 2605.

[0102] The charged drop detector of the charged drop control system can generate a voltage representative of the proximity of the ejected charged drop to a segment of the sensor layer, as described above, and the drop voltage detection control 2625 can communicate such voltage to the voltage control acquisition system 2630. Specifically, the voltage can be communicated to a voltage amplifier circuit 2635, which then sends the amplified voltage to an analog-to-digital converter 2640 to convert the voltage into a digital signal for communication to the data acquisition system 2615.

[0103] In the data acquisition system 2615, a digital signal representing the voltage may be received at an analog-to-digital (ADC) interrupt 2645 or other digital input system. The ADC interrupt 2645 may extract the raw ADC data and communicate it to a timer interrupt 2650 and / or a computing system 2655. The computing system 2655 may analyze the raw ADC data to generate position data of the charged droplets at the charged droplet detector. The timer interrupt 2650 may use information from the external interrupt 2620, for example, to determine timing information for the detection of the charged droplets. Such timing information and position data may be used by the computing system 2655 to determine the velocity or trajectory of the charged droplets. The raw ADC data and position data may be communicated to a local storage buffer 2660 for caching and / or storing the data locally within the data acquisition system 2615. A controller area network (CAN) bus 2665 or other input / output system may receive positional data and / or raw ADC data from the local storage buffer 2660 or computing system 2655 and communicate that information to a user computing device 2670 for use by an induced charge droplet detection (ICDD) application 2675 running thereon.

[0104] In the case of droplet trajectory control, the computation system 2655 may analyze the position data to determine an appropriate set of voltages to apply to segments of the control layer of the charged droplet controller in the charged droplet control detection system 2605. The voltages may be communicated in digital form, for example, to the voltage control acquisition system 2630, where a digital-to-analog converter 2680 can generate a voltage that is communicated to the droplet voltage detection control 2625 to effect a correction of the droplet trajectory.

[0105] While the subject matter of embodiments of the present invention is described with specificity herein to meet statutory requirements, this description is not intended to necessarily limit the scope of the claims. The claimed subject matter may be embodied in other ways, may include different elements or steps, and may be used in combination with other existing or future technologies. This description should not be construed as implying a particular order or arrangement of or among the various steps or elements, unless the order of individual steps or arrangement of elements is explicitly recited.

[0106] For purposes of clarity, not all of the routine features of the embodiments described herein are shown and described, it being understood, of course, that the development of any such actual implementation will require making numerous implementation-specific decisions in order to achieve the particular goals of the developer, such as compliance with application- and business-related constraints, and that these particular goals will vary from implementation to implementation and from developer to developer.

[0107] While the present subject matter has been described in detail with respect to certain embodiments thereof, it will be understood that those skilled in the art, upon gaining the foregoing understanding, may readily make alterations, modifications, and equivalents to such embodiments. Numerous specific details have been described herein to provide a thorough understanding of the claimed subject matter. However, those skilled in the art will understand that the claimed subject matter may be practiced without these specific details. In other instances, methods, apparatuses, or systems that would be known to those skilled in the art have not been described in detail so as not to obscure the claimed subject matter. Accordingly, this disclosure is presented for purposes of illustration and not limitation, and is not intended to exclude the inclusion of modifications, variations, and / or additions to the present subject matter that would be readily apparent to those skilled in the art. It will be apparent to those skilled in the art that various modifications and variations can be made to the methods and systems of the present invention without departing from the spirit or scope of the invention. Therefore, it is intended that the present invention include modifications and variations that come within the scope of the appended claims and their equivalents. It is understood that any workable combination of the features and capabilities disclosed herein is also considered to be disclosed.

Claims

1. 1. A device for detecting or controlling charged droplets from a charged droplet generator, said device comprising: a sensor element having three or more conductive layers separated by a plurality of insulating layers, the three or more conductive layers and the plurality of insulating layers defining an opening in the sensor element through which charged droplets pass, the three or more conductive layers including a first conductive layer, a second conductive layer and a third conductive layer, the second conductive layer of the three or more conductive layers being a segmented conductive layer having a plurality of divided segments electrically independent from one another and being disposed around the opening in the segmented conductive layer, the second conductive layer being disposed between the first conductive layer and the third conductive layer; a circuit element electrically coupled to each of the plurality of divided segments, each divided segment of the plurality of divided segments arranged to provide an induced current in the circuit element when a charged droplet passes through the opening, the circuit element configured to generate a plurality of signals proportional to the induced current; Including, each of the plurality of divided segments is disposed at a corresponding portion around the opening; the first conductive layer and the third conductive layer are held at a ground potential or a reference potential; each of the plurality of signals is characterized by a curve having a feature including a peak, a minimum, and a zero crossing located between the peak and the minimum; A device wherein the velocity of the charged droplet (V droplet ) is determined based on at least one of the peaks, the minimums and the zero crossings of the curve of at least one signal.

2. The device of claim 1 , wherein each of the plurality of divided segments occupies an equal portion of the circumference of the opening with one or more other divided segments.

3. The device of claim 1 , wherein the circuit element comprises a transimpedance amplifier, and the plurality of signals proportional to the induced currents comprises a plurality of voltage signals.

4. The device according to any one of claims 1 to 3, wherein the plurality of divided segments includes at least two pairs of divided segments, and the divided segments of each pair of divided segments are arranged opposite each other around the opening.

5. The device of claim 4 , wherein each pair of divided segments is disposed perpendicular to another pair of divided segments.

6. A device according to any one of claims 1 to 5, wherein the sensor element is located between a source and a target destination of the charged droplet generator.

7. The device of claim 6 , wherein the opening is aligned with an ejection axis of the charged droplet generator.

8. The device comprises: a processor; a non-transitory computer-readable storage medium in data communication with the processor; further comprising the non-transitory computer-readable storage medium storing processor-executable instructions; The processor-executable instructions, when executed by the processor, receiving the plurality of signals from the circuit element; determining a position of the charged droplet based on the plurality of signals; The device of claim 1 , configured to cause the processor to perform operations including:

9. 9. The device of claim 8, wherein the operations further include determining one or more of an arrival time of the charged droplets at the opening, a velocity of the charged droplets, a charge-to-volume ratio of the charged droplets, or the presence of one or more charged satellite droplets.

10. The device of any one of claims 8 to 9, wherein determining the position of the charged droplet includes determining a normalized signal by weighting each signal from the plurality of divided segments, and determining the position of the charged droplet based on the magnitude of the normalized signal.

11. 11. The device of claim 10, wherein weighting each signal comprises weighting each signal by a sum of all signals from the plurality of divided segments, or by a relative area or perimeter percentage of a corresponding divided segment.

12. The device comprises: a control element having a conductive control layer adjacent to one or more insulating layers, the conductive control layer and the one or more insulating layers defining a second opening in the control element through which a charged droplet passes after passing through the opening in the sensor element, the conductive control layer being a second segmented conductive layer having a second plurality of divided segments electrically independent of one another, the conductive control layer being disposed around the second opening; a voltage controller electrically coupled to each of the second plurality of divided segments, each divided segment of the second plurality of divided segments being arranged to generate an electric field as the charged droplets pass through the second opening to control the trajectory of the charged droplets, the voltage controller being configured to apply a voltage to each of the second plurality of divided segments to generate the electric field; and The device of claim 1 further comprising:

13. The device comprises: a processor; a non-transitory computer-readable storage medium in data communication with the processor; further comprising the non-transitory computer-readable storage medium storing processor-executable instructions; The processor-executable instructions, when executed by the processor, receiving the plurality of signals from the circuit element; determining a position of the charged droplet based on the plurality of signals; determining a set of voltages to apply to the second plurality of divided segments based on the positions of the charged droplets; controlling a voltage controller to apply the set of voltages to the second plurality of divided segments; The device of claim 12 , configured to cause the processor to perform operations including:

14. The device of claim 12 , wherein the second opening is aligned with the opening of the sensor element.

15. 15. The device of claim 12 or claim 14, wherein each of the second plurality of divided segments is disposed at a corresponding portion around the second opening.

16. 16. The device of claim 12 or any one of claims 14-15, wherein each of the second plurality of divided segments occupies an equal portion of the circumference of the second opening as one or more other of the second plurality of divided segments.

17. The device of any one of claims 12 or 14 to 16, wherein the second plurality of divided segments includes at least two pairs of divided segments, the divided segments of each pair of divided segments being arranged opposite each other around the second opening.

18. 18. A device according to claim 12 or any one of claims 14 to 17, wherein the control element is arranged between a source and a target destination of the charged droplet generator, or between the sensor element and a target destination of the charged droplet generator.

19. 19. The device of claim 12 or any one of claims 14-18, wherein the control element further includes a reference or ground layer separated from the conductive control layer by one or more of the plurality of insulating layers, and wherein the second opening is further defined by an opening in the reference or ground layer.

20. 20. The device of claim 12 or any one of claims 14 to 19, wherein the control element comprises two or more conductive control layers separated by a plurality of insulating layers and coupled to the voltage controller.

21. 1. A device for detecting or controlling charged droplets from a charged droplet generator, said device comprising: a control element having a conductive control layer adjacent to one or more insulating layers, the conductive control layer and the one or more insulating layers defining an opening in the control element through which charged droplets pass, the conductive control layer being a segmented conductive layer having a plurality of separated segments that are electrically independent of one another and are disposed around the opening; a voltage controller electrically coupled to each of the plurality of divided segments, each divided segment being arranged to generate an electric field as the charged droplet passes through the opening to control the trajectory of the charged droplet, the voltage controller being configured to apply a voltage to each of the plurality of divided segments to generate the electric field; a sensor element having at least one segmented sensor layer separated from the conductive control layer, the sensor element having a second plurality of divided segments electrically independent from one another and disposed around the opening; a circuit element electrically coupled to each of the second plurality of divided segments, each of the second plurality of divided segments being arranged to provide an induced current in the circuit element when a charged droplet passes through the aperture, the circuit element being configured to generate a plurality of signals proportional to the induced current; Including, each of the plurality of signals is characterized by a curve having a feature including a peak, a minimum, and a zero crossing located between the peak and the minimum; A device wherein the velocity of the charged droplet (V droplet ) is determined based on at least one of the peaks, the minimums and the zero crossings of the curve of at least one signal.

22. 22. The device of claim 21, wherein each of the plurality of divided segments is disposed at a corresponding portion of the periphery of the opening.

23. 23. The device of claim 21, wherein each of the plurality of divided segments occupies an equal portion of the circumference of the opening as one or more other divided segments.

24. A device according to any one of claims 21 to 23, wherein the control element is located between a source and a target destination of the charged droplet generator.

25. A device according to any one of claims 21 to 24, wherein the opening is aligned with an ejection axis of the charged droplet generator.

26. The device of any one of claims 21 to 25, wherein the plurality of divided segments includes at least two pairs of divided segments, the divided segments of each pair of divided segments being arranged opposite each other around the opening.

27. 27. The device of claim 26, wherein each pair of divided segments is disposed perpendicular to another pair of divided segments.

28. The device comprises: a processor; a non-transitory computer-readable storage medium in data communication with the processor; further comprising the non-transitory computer-readable storage medium storing processor-executable instructions; The processor-executable instructions, when executed by the processor, controlling the voltage controller to apply a set of voltages to the plurality of divided segments; 28. A device according to any one of claims 21 to 27, configured to cause the processor to perform operations including:

29. 1. A device for detecting or controlling charged droplets from a charged droplet generator, said device comprising:

1. A sensing device having an opening formed in the sensing device from a first surface to a second surface, the sensing device comprising: a first conductive layer on the first surface; a second conductive layer on the second surface; and a segmented sensor layer between the first conductive layer and the second conductive layer; a first dielectric layer and a second dielectric layer disposed on opposite surfaces of the segmented sensor layer, the first dielectric layer and the second dielectric layer insulating the segmented sensor layer from the first conductive layer and the second conductive layer, the segmented sensor layer including a plurality of segments disposed around the opening; a sensing device including: a circuit element coupled to each of the plurality of segments of the segmented sensor layer, each segment of the plurality of segments arranged to provide an induced current in the circuit element when a charged droplet passes through the aperture, the circuit element configured to generate a plurality of signals proportional to the induced current; Including, Each of the plurality of segments is disposed at a corresponding portion around the opening; the first conductive layer and the second conductive layer are held at a ground potential or a reference potential; each of the plurality of signals is characterized by a curve having a feature including a peak, a minimum, and a zero crossing located between the peak and the minimum; A device wherein the velocity of the charged droplet (V droplet ) is determined based on at least one of the peaks, the minimums and the zero crossings of the curve of at least one signal.

30. 30. The device of claim 29, wherein the opening is aligned with an ejection axis of the charged droplet generator.

31. The device of any one of claims 29 to 30, wherein the circuit element comprises a transimpedance amplifier.

32. The device of any one of claims 29 to 31, wherein the segmented sensor layer comprises a plurality of electrically independent segments surrounding the opening.

33. 33. The device of claim 32, wherein the segmented sensor layer includes at least four segments, the at least four segments arranged around the opening, each segment arranged opposite another segment around the opening as a pair of segments.

34. 34. The device of claim 33, wherein each pair of segments is disposed perpendicular to another pair of segments.

35. The device comprises: a processor; a non-transitory computer-readable storage medium in data communication with the processor; further comprising the non-transitory computer-readable storage medium storing processor-executable instructions; The processor-executable instructions, when executed by the processor, receiving a plurality of measurements from one or more circuit elements coupled to the segmented sensor layer corresponding to or proportional to induced currents in the plurality of segments as the charged droplet passes through the aperture; determining a position of the charged droplet based on the plurality of measurements; and 30. The device of claim 29, further comprising:

36. 36. The device of claim 35, wherein the operations further include determining one or more of an arrival time of the charged droplets at the opening, a velocity of the charged droplets, a charge-to-volume ratio of the charged droplets, or the presence of one or more charged satellite droplets.

37. the device further comprises a control device; The control device has a second opening formed therein, the control device comprising: a segmented control layer, the segmented control layer including a second plurality of segments disposed around the second opening; and a voltage controller coupled to each of the second plurality of segments of the segmented control layer; 30. The device of claim 29, comprising:

38. 38. The device of claim 37, wherein the second opening is aligned with the opening of the sensing device.

39. The device of any one of claims 37 to 38, wherein the segmented control layer comprises a plurality of electrically independent segments surrounding the second opening.

40. 40. The device of claim 39, wherein the segmented control layer includes at least four segments arranged around the opening, each segment arranged opposite another segment around the second opening as a pair of segments.

41. 41. The device of claim 40, wherein each pair of segments is disposed perpendicular to another pair of segments.

42. The device comprises: a processor; a non-transitory computer-readable storage medium in data communication with the processor; further comprising the non-transitory computer-readable storage medium storing processor-executable instructions; The processor-executable instructions, when executed by the processor, receiving a plurality of measurements from one or more circuit elements coupled to the segmented sensor layer corresponding to or proportional to induced currents in the plurality of segments as the charged droplet passes through the aperture; determining a position of the charged droplet based on the plurality of measurements; determining a set of control voltages based on the position of the charged droplet; applying the set of control voltages to the second plurality of segments using the voltage controller to modify the trajectories of the charged droplets; generating a plurality of signals proportional to said induced currents; 38. The device of claim 37, further comprising:

43. 43. The device of claim 42, wherein the set of control voltages is determined based on one or more of the position of the charged droplets, the velocity of the charged droplets, or a predetermined position of a target.

44. 1. A device for detecting or controlling charged droplets from a charged droplet generator, said device comprising: A control device having an opening formed therein, the control device comprising: a segmented conductive layer, the segmented conductive layer including a plurality of segments disposed around the opening; a voltage controller coupled to each of the plurality of segments of the segmented conductive layer; a control device including: a sensor element having at least one segmented sensor layer separated from the segmented conductive layer, the sensor element having a second plurality of segments electrically independent from one another and disposed around the opening; a circuit element electrically coupled to each of the second plurality of segments, each of the second plurality of segments arranged to provide an induced current in the circuit element when a charged droplet passes through the aperture, the circuit element configured to generate a plurality of signals proportional to the induced current; Including, each of the plurality of signals is characterized by a curve having a feature including a peak, a minimum, and a zero crossing located between the peak and the minimum; A device wherein the velocity of the charged droplet (V droplet ) is determined based on at least one of the peaks and minima and zero crossings of the curve of at least one signal.

45. 45. The device of claim 44, wherein the opening is aligned with an ejection axis of the charged droplet generator.

46. The device of any one of claims 44 to 45, wherein the segmented conductive layer comprises a plurality of electrically independent segments surrounding the opening.

47. 47. The device of claim 46, wherein the segmented conductive layer comprises at least four segments, the at least four segments being arranged around the opening, each segment being arranged opposite another segment around the opening as a pair of segments.

48. 48. The device of claim 47, wherein each pair of segments is disposed perpendicular to another pair of segments.

49. The device comprises: a processor; a non-transitory computer-readable storage medium in data communication with the processor; further comprising the non-transitory computer-readable storage medium storing processor-executable instructions; The processor-executable instructions, when executed by the processor, applying a set of control voltages to the plurality of segments using the voltage controller to control the trajectory of the charged droplets as they pass through the aperture.

45. The device of claim 44, further comprising:

50. 50. The device of claim 49, wherein the operations further include determining the set of control voltages based on one or more of a known position of the charged droplets, a known velocity of the charged droplets, or a predetermined position of a target.

51. 1. A method for detecting or controlling charged droplets from a charged droplet generator, the method comprising: directing the charged droplets toward a target and through an opening in a charged droplet detector; measuring, in the charged droplet detector, a plurality of values ​​corresponding to an induced current, the induced current being generated when the charged droplet passes through the aperture; determining a position of the charged droplet by analyzing the plurality of values ​​corresponding to the induced current; generating a plurality of signals proportional to said induced currents; Including, each of the plurality of signals is characterized by a curve having a feature including a peak, a minimum, and a zero crossing located between the peak and the minimum; A method wherein the velocity of the charged droplets (V droplet ) is determined based on at least one of the peaks and minima and the zero crossings of the curve of at least one signal.

52. 52. The method of claim 51, wherein the method further comprises determining a total charge of the charged droplets based on the plurality of values.

53. A method according to any one of claims 51 to 52, wherein the method further comprises reversing the polarity of the charged drop detector to form a charged drop gate.

54. 54. The method of any one of claims 51 to 53, wherein the method further comprises identifying satellite droplets based on the plurality of values.

55. determining the location of the charged droplet by analyzing the plurality of values; determining a difference between a plurality of measurements from a plurality of segments of the charged drop detector located on opposite sides of the opening of the charged drop detector; determining an axial position between the plurality of segments located on opposite sides of the opening based on the difference between the plurality of measurements; and 55. The method of any one of claims 51 to 54, comprising:

56. directing the charged droplets includes directing the charged droplets through a second opening in a charged droplet controller; The method comprises: determining a set of voltages to apply to the charged droplet controller to control the trajectory of the charged droplets toward the target, the set of voltages being determined based on the position of the charged droplets; applying said set of voltages to said charged droplet controller; 56. The method of any one of claims 51 to 55, further comprising:

57. 57. The method of claim 56, wherein determining the set of voltages includes determining magnitudes of voltages to apply to multiple segments of the charged droplet controller located on opposite sides of the second opening to modify the trajectory of the charged droplet from its position at the charged droplet detector toward the target.

58. 58. The method of any one of claims 51 to 57, further comprising determining one or more of the arrival time of the charged droplets at the aperture, the velocity of the charged droplets, the charge-to-volume ratio of the charged droplets, or the presence of one or more charged satellite droplets.

59. 59. The method of claim 58, wherein determining the velocity of the charged droplets comprises determining a time period between the charged droplet ejection or generation signal and one or more peaks of the plurality of values.

60. 1. A method for detecting or controlling charged droplets from a charged droplet generator, the method comprising: directing the charged droplets toward a target and through an opening in a charged droplet controller; measuring a plurality of values ​​corresponding to an induced current in a sensor element separate from the charged droplet controller, the sensor element having a plurality of segments arranged around the aperture, the induced current being generated when the charged droplet passes through the aperture; applying a set of voltages to the charged droplet controller to control the trajectory of the charged droplets toward the target; generating a plurality of signals proportional to said induced currents; Including, each of the plurality of signals is characterized by a curve having a feature including a peak, a minimum, and a zero crossing located between the peak and the minimum; A method wherein the velocity of the charged droplets (V droplet ) is determined based on at least one of the peaks and minima and the zero crossings of the curve of at least one signal.

61. The method comprises: determining the set of voltages to apply to a plurality of segments of the charged droplet controller located on opposite sides of the aperture to modify the trajectory of the charged droplet based on one or more of a known position of the charged droplet, a known velocity of the charged droplet, or a predetermined position of the target.

61. The method of claim 60, further comprising:

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