Evaporation device and evaporation method

Abstract

An evaporation method and evaporation device for evaporating a portion of a liquid in a sample container are described, the evaporation device comprising: a sample holder for holding the sample container; a light source; a photodetector configured to output an electronic signal indicative of a characteristic of light received by the photodetector; an optical fiber assembly configured to transmit light emitted by the light source along an optical path through at least a portion of the sample container when placed in the sample holder and to transmit light that has traveled along the optical path to the photodetector; and a controller in electrical contact with the photodetector, the controller configured to obtain the electronic signal and control the evaporation device to terminate evaporation based on the electronic signal.

Description

[Technical Field]

[0001] This patent disclosure relates to the area of ​​solvent evaporation. This patent disclosure also relates to the field of liquid level detection. Particular examples relate to evaporation devices and methods for evaporating a portion of a liquid in a sample container. [Background technology]

[0002] Evaporators are often found in many types of laboratories, from drug discovery to analytical chemistry laboratories, to remove solvents from samples by solvent evaporation. Sample containers containing samples, which may contain analytes in the solvent, are often heated to increase the vapor pressure of the solvent. Heating can be achieved by partially immersing the sample container in a heatable liquid bath or tank, such as a hot water bath. To increase the evaporation rate, one type of evaporator uses a nozzle to direct a gas stream into the sample container.

[0003] However, analytes may contain sensitive components, such as certain proteins or polymers, that require at least some solvent to maintain stability. Therefore, evaporation should be stopped before all of the solvent has evaporated. The evaporation device may also include an electro-optical detector positioned at a specific height above the sample container to detect the liquid level within the container. These electro-optical detectors often fail, especially when submerged in a heated liquid bath, and require replacement, potentially resulting in loss of analyte if they malfunction during evaporation. Additionally, electronic components can cause unsafe sparks when placed near flammable fluids.

[0004] According to the abstract of patent document WO 2018 / 103851, the invention relates in particular to an extraction or evaporation device comprising at least one receiver for the container, at least one heating element for the container, at least one light source, at least one sensor and an evaluation unit. The light source and / or sensor are arranged outside the container such that a light signal generated by the light source and passing through the container can be detected by the sensor.

[0005] According to the abstract of Korean Patent No. 102272898, a patent document, the present invention relates to an evaporative concentration apparatus for analyzing radioactive materials, which comprises a hot plate having a predetermined shape and a water level measurement unit. The evaporative concentration apparatus for analyzing radioactive materials is equipped with a water level measurement unit that can confirm the volume of the remaining evaporated and concentrated amount, thereby improving the working environment.

[0006] Patent document U.S. Pat. No. 5,054,319 describes, in its abstract, a liquid level sensor system including a float assembly configured for placement within a liquid. The float assembly includes a float sufficiently buoyant to move the float assembly vertically in response to changes in the liquid level. The float assembly may include a buoyant member disposed about a tube and constrained to move only longitudinally along the tube in response to changes in the liquid level. A reflector may be coupled to the float, with the reflector being a function of the liquid level. A carriage may be disposed within the tube, and the reflector may be attached to the carriage, for movement with the float in response to changes in the liquid level. The carriage and float are preferably magnetically coupled, such that the carriage means moves longitudinally within the tube in response to movement of the float assembly as the liquid level changes. A light source directs an optical signal toward the reflector. Light reflected from the reflector is processed in a feedback loop to control the frequency of a feedback-induced amplitude modulation of the optical signal as a function of an optical path length that is dependent on the liquid level. The frequency of the amplitude-modulated signal is measured to determine the liquid level. Summary of the Invention [Problem to be solved by the invention]

[0007] Among the objects of the present disclosure, one object is to provide improved evaporation devices and methods. [Means for solving the problem]

[0008] According to a first aspect, there is provided an evaporation device for evaporating a portion of a liquid in a sample container, the evaporation device comprising: a sample holder for holding the sample container; a light source; a photodetector configured to output an electronic signal indicative of a characteristic of light received by the photodetector; an optical fiber assembly configured, when positioned in the sample holder, to transmit light emitted by the light source along an optical path through at least a portion of the sample container and to transmit light that has traveled along the optical path to the photodetector; and a controller in electrical contact with the photodetector, the controller configured to obtain the electronic signal and control the evaporation device to terminate evaporation based on the electronic signal.

[0009] Advantageously, evaporation devices with optical fiber assemblies allow the light source and photodetector to be located away from the sample container. Furthermore, electrical wiring to the sample container is no longer necessary. This increases the safety of the evaporation device, especially in the presence of flammable fluids such as solvents.

[0010] Optionally, in some examples, the controller may be configured to control the evaporation device to obtain the electronic signal and determine an evaporation endpoint based on the electronic signal. Once the evaporation endpoint is determined, the evaporation device may terminate evaporation. The evaporation endpoint may be determined when the liquid level is at or near the optical path.

[0011] Optionally, in some examples, the optical path is offset relative to the central longitudinal axis of the sample container when placed in the sample holder. The optical path may be offset by positioning the optical fiber assembly so that the optical path is offset relative to the central longitudinal axis along which the sample container can be placed in the evaporation device. Thus, the optical path does not intersect the longitudinal axis and passes through the sample container when placed in the sample holder. In other words, the optical path has a non-zero angle relative to the wall of the sample container when placed in the sample holder. Advantageously, this offset allows more light to have an angle relative to the sample container wall, which increases the change in intensity when the medium in the sample container changes from water to air, thus improving the determination of when to terminate evaporation or liquid level detection. In other words, when more light has an angle relative to the sample container wall, sensitivity to changes in refractive index within the sample container can be increased.

[0012] Optionally, in some examples, the evaporation device further comprises a reflector comprising a reflective surface disposed at the end of and toward the optical path. The reflector is preferably a retroreflector, such as a microcube corner retroreflector. By using a reflector, the light is reflected (at least partially) along the optical path, allowing either the receiving fiber end or the same fiber end from which the light originates to be positioned on one side of the sample container position, thus reducing the number of fiber positions in the evaporation device.

[0013] When a retroreflector is used, more light is reflected in the same direction along the optical path, thus increasing the amount of light received by the optical fiber assembly and subsequently by the optical detector. When a microcube corner retroreflector is used, the deviation of the return path that the light takes relative to the path toward the retroreflector is reduced compared to retroreflectors with larger optical resolution for reflecting backlight light.

[0014] Alternatively, the reflector may be a diffuse reflector configured to reflect a first range of wavelengths that at least overlaps with a second range of wavelengths emitted by the light source.

[0015] Optionally, in some examples, a reflector is positioned such that when the sample container is placed in the sample holder, light passing through the sample container is at least partially reflected in an opposite direction along the optical path.

[0016] Optionally, in some examples, the optical fiber assembly is configured to receive light emitted by the light source, emit at least a portion of the received light emitted by the light source along an optical path in which at least a portion of the sample container can be positioned, receive light that has traveled along the optical path, and emit at least a portion of the received light that has traveled along the optical path toward the light detector.

[0017] Optionally, in some examples, the optical fiber assembly comprises one or more optical fibers comprising a first optical fiber end, a second optical fiber end, and a third optical fiber end, the one or more optical fibers being arranged such that the first optical fiber end is positioned to receive light emitted by the light source, the second optical fiber end is positioned to emit at least a portion of the received light emitted by the light source along an optical path, and the third optical fiber end is positioned to emit at least a portion of the received light that has traveled along the optical path towards the photodetector.

[0018] Optionally, in some examples, a reflector, preferably a retroreflector, is disposed opposite the second optical fiber end of the one or more optical fibers, the reflector being configured to reflect light emitted by the second optical fiber end toward the second optical fiber end.

[0019] Optionally, in some examples, the optical fiber assembly includes an optical fiber having a first optical fiber end, a second optical fiber end, and a third optical fiber end, the first optical fiber including an optical splitter, a first fiber path through the first optical fiber traveling from the first optical fiber end to the second optical fiber end via the optical splitter, and a second fiber path traveling from the second optical fiber end to the third optical fiber end via the optical splitter. In this way, only the portion of the fiber from the splitter toward the second optical fiber end can extend toward the sample container location within the evaporation device. This limits the number of components toward the sample container, leaving more space for, for example, adding more sample containers and / or reducing the size of the evaporation device.

[0020] Alternatively, the one or more optical fibers may comprise a first optical fiber and a second optical fiber, the first optical fiber comprising a first optical fiber end and a second optical fiber end, and the second optical fiber comprising a third optical fiber end and a fourth optical fiber end for receiving light passed along the optical path.

[0021] Optionally, in some examples, a fourth optical fiber end is disposed at the other end of the optical path opposite the second optical fiber end. In this case, a reflector is not required. In an alternative example, the evaporation device may include a reflector, and the fourth optical fiber end may be disposed adjacent to the second optical fiber end. The first and second optical fibers may then be bundled together within the evaporation device.

[0022] Additionally, there is the option of providing one or more of the third through seventh optical fibers, which may be bundled together. Two or more, e.g., six, optical fibers are then bundled around the first optical fiber, while the first optical fiber may be the fiber that emits light. The second, third, etc., e.g., seventh optical fibers all guide the received light to an optical detector in this example.

[0023] The evaporation device may include multiple sample vessel locations, i.e., the sample holder may include multiple receiving openings for a corresponding number of sample vessels, and the fiber optic assembly may be configured to control evaporation of all of these sample vessels.

[0024] Optionally, in some examples, the optical splitter is configured to disperse light in a ratio within a range of 20:80 to 80:20, such as 40:60 to 60:40, for example 50:50.

[0025] Optionally, in some examples, the controller comprises a processing circuit comprising a processor and a memory, the processing circuit being in electrical contact with the photodetector, and the processor and memory comprising: an acquisition module configured to acquire an electronic signal from the photodetector; a determination module configured to determine whether to terminate evaporation based on the acquired electronic signal; and a termination module configured to terminate evaporation if the determination module determines to terminate evaporation.

[0026] Optionally, in some examples, the characteristic property of the light received by the photodetector comprises at least one of light intensity, a change in light intensity, wavelength, a change in wavelength, polarization, and a change in polarization.

[0027] Optionally, in some examples, the characteristic characteristic is light intensity or a change in light intensity. Optionally, in some examples, the controller is configured to control the evaporation device to terminate evaporation when the electronic signal indicates that the light intensity or change in light intensity is above or below a threshold light intensity or change in light intensity, respectively.

[0028] Optionally, in some examples, the evaporation device includes at least one nozzle, the sample holder is configured to hold the sample container in a predetermined position relative to the at least one nozzle, the evaporation device is configured to supply a gas flow through the at least one nozzle so that a vortex is formed in the liquid to be evaporated in the sample container when the evaporation device is in use, and the controller is configured to control the evaporation device to terminate the evaporation by terminating the gas flow to the sample container.

[0029] In general, terminating evaporation may mean terminating at least the relevant operation so that the evaporation rate of the liquid in the sample container is reduced. In reality, liquids always have a constant vapor pressure and the liquid may still evaporate to some extent.

[0030] Optionally, in some examples, when the evaporation device comprises a heatable liquid tank and the heatable liquid tank contains a liquid, the sample holder is positioned such that the sample container is at least partially immersed in the liquid in the heatable liquid tank when placed in the sample holder, and the light source, light detector and controller are positioned outside the heatable liquid tank.

[0031] Optionally, in some examples, the controller is configured to control the evaporation device to terminate evaporation by terminating heating of the heatable liquid reservoir.

[0032] Optionally, in some examples, the light path correlates to a predetermined liquid level in the sample vessel at which evaporation is terminated.

[0033] Additionally or alternatively, the light source is configured to emit light having a wavelength in the range of 650 to 1000 nm, preferably 700 to 980 nm, more preferably 750 to 950 nm.

[0034] Additionally or alternatively, the photodetector comprises a phototransistor or a photodiode.

[0035] According to a second aspect of the present disclosure, there is provided a method for evaporating a portion of a liquid evaporating in a sample container, the method including: performing evaporation of the liquid in the sample container; transmitting light from a light source along an optical path through at least a portion of the sample container using an optical fiber assembly; transmitting the light that has passed through the optical path to a photodetector; generating, by the photodetector, an electronic signal indicative of a characteristic of the light detected by the photodetector; and terminating the evaporation based on the electronic signal.

[0036] Optionally, in some examples, transmitting light from the light source to the sample container includes receiving light emitted by the light source by a first end of one or more optical fibers and emitting at least a portion of the light received by the first end along an optical path by a second end of the one or more optical fibers; transmitting the light that has passed through the optical path to the photodetector includes receiving light emitted by a second optical fiber end that has passed through the sample container by a third end of one or more of the one or more optical fibers; emitting the light received by the second optical fiber end toward the photodetector by the third optical fiber end of the one or more optical fibers; generating an electronic signal by the photodetector indicating a characteristic of the light detected by the photodetector; and terminating the evaporation based on the electronic signal.

[0037] Optionally, in some examples, the evaporation device is an evaporation device according to any one of the examples of the evaporation device according to the first aspect of the present patent disclosure.

[0038] According to a third aspect of the present disclosure, there is provided a liquid level detection system for detecting a liquid level in a sample container. The liquid level may be a meniscus level. The liquid level detection system includes a light source, a photodetector configured to output an electronic signal indicative of a characteristic of light received by the photodetector, an optical fiber assembly configured to transmit light from the light source along an optical path in which at least a portion of the sample container can be disposed and to transmit the light passing through the optical path to the photodetector, and a controller in electrical contact with the photodetector, the controller configured to receive the electronic signal and detect whether the liquid level is at or near the optical path.

[0039] The liquid level detection system can be used, for example, in an evaporation system such as that described in this patent disclosure, or in a capillary viscometer for determining the kinematic viscosity of a sample, among other things. In the latter viscometer, which may also be known as an Ubbelohde viscometer or a suspension viscometer, the liquid level detection system is configured to detect first and second liquid levels or menisci to determine the time it takes for a fluid to travel along a fixed path length through a vertical U-tube. Thus, one aspect of the present disclosure is a capillary viscometer including a liquid level detection system.

[0040] Optionally, in some examples, the liquid level detection system further comprises a reflector comprising a reflective surface disposed at an end of and toward the light path. The reflector is preferably a retroreflector, such as a microcube corner retroreflector. By using a reflector, the light is reflected (at least partially) along the light path, allowing either the receiving fiber end or the same fiber end from which the light originates to be positioned on one side of the sample container position, thus reducing the number of fiber positions.

[0041] When a retroreflector is used, more light is reflected back along the optical path, thus increasing the amount of light received by the optical fiber assembly and subsequently by the optical detector. When a microcube corner retroreflector is used, the deviation of the return path taken by the light relative to the path toward the retroreflector is reduced compared to a retroreflector with a larger optical resolution for reflecting the light back. Alternatively, the reflector may be a diffuse reflector. The diffuse reflector may be configured to reflect a first wavelength range that at least overlaps with a second wavelength range of the light source.

[0042] Optionally, in some examples, a reflector is positioned such that, in the presence of a sample container, light passing through the sample container is reflected in the opposite direction along the light path.

[0043] Optionally, in some examples, the optical fiber assembly comprises one or more optical fibers comprising a first optical fiber end, a second optical fiber end, and a third optical fiber end, the one or more optical fibers being arranged such that the first optical fiber end is positioned to receive light emitted by the light source, the second optical fiber end is positioned to emit at least a portion of the received light emitted by the light source along an optical path, and the third optical fiber end is positioned to emit at least a portion of the received light that has traveled along the optical path towards the photodetector.

[0044] Optionally, in some examples, a reflector, preferably a retroreflector, is disposed opposite the second optical fiber end of the one or more optical fibers, the retroreflector being configured to reflect light emitted by the second optical fiber end toward the second optical fiber end.

[0045] Optionally, in some examples, the optical fiber assembly includes one optical fiber having a first optical fiber end, a second optical fiber end, and a third optical fiber end, the first optical fiber including an optical splitter, a first fiber path through the first optical fiber traveling from the first optical fiber end to the second optical fiber end through the optical splitter, and a second fiber path traveling from the second optical fiber end to the third optical fiber end through the optical splitter. In this way, only the portion of the fiber going from the splitter to the second optical fiber end can extend toward the sample container location. This limits the number of components going toward the sample container, leaving more space for, for example, adding more sample containers and / or reducing the size of the device in which the liquid level detection system is used.

[0046] It will be appreciated that any further features, examples, and advantages associated with these further features and examples according to the above aspects may be readily applied to the liquid level detection system of the present invention.

[0047] According to a fourth aspect of the present patent disclosure, there is provided a control system for an evaporation device for evaporating a portion of a liquid in a sample container, the control system comprising a light source, a photodetector configured to output an electronic signal indicative of a characteristic of light received by the photodetector, an optical fiber assembly configured to transmit light from the light source along an optical path in which at least a portion of the sample container can be positioned and to transmit light that has passed along the optical path to the photodetector, and a controller in electrical contact with the photodetector, the controller configured to obtain the electronic signal and control the evaporation device to terminate evaporation based on the electronic signal.

[0048] It will be appreciated that any of the features, examples, and advantages associated with these features and examples of the liquid level detection system and evaporation device according to the above embodiments may be readily applied to the control system of the present invention.

[0049] According to another aspect of the present disclosure, there is provided an evaporation device comprising a control system according to the fourth aspect or a liquid level detection system according to the third aspect.

[0050] It will be understood that technical advantages and benefits associated with features and / or examples of one embodiment generally apply to corresponding, similar, or equivalent features and / or examples of other embodiments. It will also be apparent that features of various embodiments and / or examples thereof may be applied to other embodiments and / or examples.

[0051] BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are used to illustrate presently preferred, non-limiting illustrative examples of the apparatus of the present disclosure. The above and other advantages of the features and objects of the present disclosure will become more apparent, and the aspects and examples will be better understood from the following detailed description when read in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0052] [Figure 1] 1 is a schematic diagram of an evaporation device according to some examples of the present patent disclosure. [Figure 2] 1 is a schematic side view of an optical fiber assembly and a sample vessel positioned according to certain examples of the present patent disclosure. [Figure 3] 1 is a schematic side view of an optical fiber assembly and a sample vessel positioned according to certain examples of the present patent disclosure. [Figure 4] 1 is a schematic side view of an optical fiber assembly and a sample vessel positioned according to certain examples of the present patent disclosure. [Figure 5] 1 is a schematic diagram of light rays directed toward and passing through a sample container when water is present in the sample container. [Figure 6] 6 is a schematic diagram of light rays directed toward and passing through the sample vessel of FIG. 5 when air is present in the sample vessel. [Figure 7] 6 is a schematic top view of the optical fiber assembly of FIG. 4 and the sample container positioned according to FIG. 5, showing the light beam passing through the sample container. [Figure 8] 3 is a plot showing the time of the detected optical signal of the optical fiber assembly according to FIG. 2; [Figure 9] 8 is a plot showing the time of the detected optical signal of the optical fiber assembly according to FIGS. 4 and 7 with a reflector. DETAILED DESCRIPTION OF THE INVENTION

[0053] Detailed Description In FIG. 1 , an evaporation apparatus, generally designated 1, includes a sample holder 108 for holding a sample container 100. The evaporation apparatus includes a control system, or liquid level detection system, including a light source 210 and a photodetector 220 configured to output an electronic signal indicative of a characteristic of light received by the photodetector 220. The control system and / or liquid level detection system includes an optical fiber assembly 230 configured to transmit light emitted by the light source 210 along an optical path 250 through at least a portion of the sample container 100 when positioned in the sample holder 108 and transmit light traveling along the optical path 250 to the photodetector 220. The control system and / or liquid level detection system includes a controller 240 in electrical contact with the photodetector 220. The controller 240 is configured to obtain the electronic signal and control the evaporation apparatus 1 to terminate evaporation based on the electronic signal. The light source 210, the photodetector 220, and the controller 240 are included in an electronics unit 200 in this example.

[0054] The optical fiber assembly 230 in this example includes an optical fiber 242 with an optical fiber end 248 and a reflector 260. An optical path 250 extends from the optical fiber end 248 toward the reflector 260. The sample container 100 is disposed between the optical fiber end 248 and the reflector 260. The optical path 250 passes through the sample container 100. Evaporation, in this case, will terminate when the liquid level drops to or near the optical path 250. The configurations and functions of the optical fiber assembly 230, the light source 210, the photodetector 220, and the controller 240 are further described below with reference to Figures 2-7.

[0055] The evaporation device 1 may include a control unit 104 for controlling the evaporation process. The control unit 104 may be configured to include, be, or perform the functions of the controller 240.

[0056] An example of an evaporation device 1 will now be described, in which a heatable liquid tank is used to heat sample containers to a predetermined temperature. Thus, the evaporation device 1 may include a heatable liquid tank, here embodied as a liquid tank unit 103 with an associated heater 113 for heating the liquid. A sample holder 108 may be inserted into the tank unit 103 and configured to hold at least one sample container 100. The evaporation system may include a temperature sensor 110 connected to the control unit 104. The temperature sensor 110 is configured to measure the temperature of the liquid in the tank unit 103. The temperature sensor 110 may be located away from the bottom of the tank unit, allowing the liquid level in the tank unit to be determined. This may be determined by the control unit when the heater is activated but no temperature increase is detected by the temperature sensor.

[0057] Furthermore, the evaporation device may include an additional temperature sensor 112 configured to sense the temperature of the heater 113. In this way, the heater is protected from possible overheating when the tank unit is empty, which means that the temperature sensor in the tank unit does not sense the temperature.

[0058] The control unit 104 may be configured to control the temperature of the liquid in the tank by means of a heater 113 and a temperature sensor 110 .

[0059] The following describes an example of an evaporation device 1 in which a gas is injected into a sample container to create a vortex in order to control the evaporation of liquid from the sample container. However, the detection of the liquid level and / or end point of evaporation can also be used in other evaporation systems that do not have such a vortex generating means.

[0060] The evaporation device 1 may include at least one nozzle 102. A sample holder 108 may be configured to hold at least one sample container 100 in a defined position relative to the at least one nozzle 102. A pressure regulator 106 is controlled by the control unit 104 and is supplied with gas via a gas inlet port 105. The gas is supplied from the pressure regulator 106 to a control valve 107 arranged downstream of the pressure regulator 106. Each of the at least one nozzle 102 may be connected to a corresponding controllable output port 117 of the control valve 107. The control valve 107 is controlled by the control unit 104. The control unit 104 may be configured to control the pressure regulator 106. The setpoint of the pressure regulator 106 is controlled by the control unit 104.

[0061] The vaporizer may include a control valve 107 disposed downstream of the pressure regulator 106. The control unit is configured to set the pressure regulator to a setpoint that results in a predetermined gas flow from each of the at least one nozzle 102, the pressure setpoint depending on the number of active nozzles connected to the control valve and the desired gas flow from a single nozzle. The control unit 104 is operable to select which nozzles 102 to allow gas flow through the control valve. Additionally or alternatively, individual nozzles may be blocked with caps.

[0062] Additionally, the control unit may be configured to gradually increase the gas pressure from the pressure regulator over a predetermined period of time, thereby achieving optimal vortex motion throughout evaporation.

[0063] Additionally, the control unit 104 may be configured to gradually increase the gas pressure from the pressure regulator to the control valve unit, in this way the vortex motion builds up gradually, which means that splatter can be minimized.

[0064] Additionally, the control valve unit 107 may include a plurality of electrically operated valves, each connected to a corresponding nozzle 102. This allows the control unit 104 to control which nozzles are activated. Additionally, the pressure regulator 106 may include a pressure sensor connected to the control unit 104. In this manner, a measured pressure associated with the flow from each nozzle 102 in the evaporator apparatus may be presented on the display unit 111.

[0065] Optionally, in some examples, optical fiber assembly 230 comprises one or more optical fibers, including at least one optical fiber for each sample container 100 in which a liquid level is to be detected and / or an evaporation endpoint is to be detected. The one or more optical fibers comprise a first optical fiber end 446, a second optical fiber end 448, and a third optical fiber end 450. The one or more optical fibers are arranged such that first optical fiber end 446 is positioned to receive light emitted by light source 210, second optical fiber end 448 is positioned to emit at least a portion of the received light emitted by light source 210 along optical path 250, and third optical fiber end 450 is positioned to emit at least a portion of the received light that has traveled along optical path 250 toward photodetector 220.

[0066] An example of a control system or liquid level detection system, commonly referred to as a "system," is shown in FIG. 2. In system 400, one or more optical fibers include a first optical fiber 442 and a second optical fiber 462. First optical fiber 442 includes a first optical fiber end 446 and a second optical fiber end 448. Second optical fiber 462 also includes a fourth optical fiber end 464 positioned to receive light passing along optical path 250. Second optical fiber 462 includes a third optical fiber end 450, which is positioned relative to optical detector 220 to receive at least a portion of the light passing along optical path 250 and received by fourth optical fiber end 464. Fourth optical fiber end 464 is located on the opposite side of sample container 100 from second optical fiber end 448. Fourth optical fiber end 464 is preferably located at the same height as second optical fiber end 448. In this example, a reflector is not required. Various optical components, such as lenses, may be included in system 400 in front of the various optical fiber ends to increase the light received by the various optical fiber ends and ultimately by optical detector 220 .

[0067] FIG. 3 illustrates another example of a control system and liquid level detection system using a reflector 260. System 500 is configured similarly to system 400, except that a second optical fiber 462 is located on the same side of sample container 100 as first optical fiber 442. A third optical fiber end 464 is located adjacent to second optical fiber end 448. Reflector 260 is located on the opposite side of optical path 250 from second optical fiber end 448 and third optical fiber end 464. In some examples, reflector 260 is a retroreflector, such that light emitted by optical fiber end 448 is returned in approximately the same direction. The retroreflector may be a cube-corner array retroreflector, such as a microcube-corner array retroreflector. Advantageously, the fibers may be at least partially bundled here to reduce the space occupied, for example, when used in an evaporation device. The retroreflector in this example has a circular shape, but any shape would work.

[0068] 4 is yet another example of a control system and a liquid level detection system using a reflector 260. System 600 is configured similarly to system 500, except that a single optical fiber 442 is present, and a second optical fiber end 448 also receives light that passes along optical path 250 and is reflected by reflector 260. Optical fiber 442 further includes a third optical fiber end 450. Optical fiber 442 includes an optical splitter 610. A first fiber light path through optical fiber 442 extends from first optical fiber end 446 to second optical fiber end 448 (or vice versa) via first optical fiber branch 612 and optical splitter 610. A second fiber light path extends from second optical fiber end 448 to third optical fiber end 450 (or vice versa) via optical splitter 610 and second optical fiber branch 614. In this way, system 600 includes fewer parts, is easier to install, and takes up less space, leaving more volume, for example, to add more sample containers and / or to reduce the size of the device in which system 600 is used.

[0069] 5 and 6 illustrate the effect of shear when the medium present in the interior 203 of the sample container 100 changes from water (FIG. 5) to air (FIG. 6) while the sample container 100 is submerged in water. The sample container 100 includes a container wall 201. A light ray 204 is shown emanating from point 206, which may be, for example, a point on the tip of an optical fiber, or a lens or other suitable optical element in front of the tip of the optical fiber. When the medium changes from water to air, the refractive index of the interior 203 of the sample container 100 changes, causing the light ray to be more dispersed by the air present in the interior 203 than by the water present in the former. A situation in which the medium in the container 100 changes from water to air occurs, for example, when water in the container 100 evaporates until the water level drops below the light path 250.

[0070] FIG. 7 shows a top view of the system 600 with the sample container 100 of FIG. 5 . The optical fiber end 448 is offset by an offset 710 relative to a radial axis 702 that extends perpendicularly from a central longitudinal axis 700, along which the longitudinal axis of the sample container is typically aligned. Thus, the optical path 250 is at least partially offset relative to the central longitudinal axis of the sample container 100. The optical path 250 (not shown in FIG. 7 for clarity) may be at an angle relative to the radial axis 702, depending on the dimensions of the sample container 100. For example, the optical path in the top view of FIG. 7 may extend from the second optical fiber end 448 to the center of the retroreflector 260 along its longest side, which faces the second optical fiber end 448. Thus, the optical path may indicate the direction in which the optical fiber end 448 is pointed. In other words, the optical path may indicate the average path that light travels from the second optical fiber end 448 toward the retroreflector 260.

[0071] When system 400 is configured as system 600 of Figure 7, fourth optical fiber end 464 may be located anywhere along the length axis where reflector 260 of Figure 7 is located. Preferably, the surface or tip face of fourth optical fiber end 464 is approximately perpendicular to optical path 250.

[0072] Advantageously, this offset causes more light to be at an angle relative to the sample container wall which increases the change in intensity when the medium in the sample container changes from water to air, thus improving the determination of when to terminate evaporation or liquid level detection. In other words, if more light is at an angle relative to the sample container wall, sensitivity to changes in refractive index within the sample container may be increased.

[0073] An exemplary data plot of the photodetector signal versus time for the system 400 of FIG. 2 is shown in FIG. 8. The photodetector signal data was acquired at a frequency of 100 Hz. A moving average filter averaging the most recent 100 samples was applied to the data in FIG. 8. The photodetector signal was normalized, with a photodetector signal value of 1 indicating a saturated level of the photodetector and a value of 0 indicating no detectable light was received by the photodetector. Air is blown at an angle at least partially above the liquid in the sample container, causing the liquid to begin to rotate relative to the sample container and forming a vortex within the liquid. The vortex creates a deep, wavy meniscus. The noise seen in the signal may be caused at least in part by the wavy meniscus through the optical path 250 or by the wavy meniscus through at least the path of the light passed through the sample container and detected by the photodetector 220. In this case, the light passed through the optical path is received by a second optical fiber, and the presence of the wavy meniscus causes scattered light, disrupting the received signal and increasing the noise. However, it is clear that the fluid level and / or desired endpoint can be obtained using the system 400. An exemplary threshold level 800 is shown in the figure. When the (average) signal value falls below this level, evaporation may terminate. Note that depending on the type of photodetector used and how it is connected in the electrical circuit, the signal value may be inverted. In this case, when the (average) signal value increases above level 800, evaporation may terminate.

[0074] Generally, evaporation may end when the (average, e.g., moving average) signal value exceeds a threshold level, such as threshold level 800 or 900. The data in Figure 8 shows that evaporation has not ended, so the signal level continues to decrease after exceeding threshold level 800. If evaporation had ended, the signal level would decrease or remain constant after exceeding threshold level 800.

[0075] Exemplary data plots of the photodetector signal versus time for system 600 are shown in Figure 9. The data was acquired and processed in the same manner as in Figure 8. A circular, 6 mm diameter retroreflector was used. The distance between the retroreflector and the second optical fiber end 448 was 11 mm. The measured sample container diameter was 10 mm. The tip offset relative to the radial axis 702 was approximately 2 mm. Comparing the data in Figure 9 to that in Figure 8, the system with the retroreflector substantially reduces the amount of noise compared to the data in Figure 8 for the fiber-to-fiber configuration of system 400 in Figure 2. Without being bound by any theory, noise is reduced in system 600 compared to system 400 because light is reflected toward the second fiber end 448 at a velocity much faster than the velocity of any waves in the vortex, resulting in less interference from scattering caused by the presence of waves in the vortex. In other words, even though the light emitted by second fiber end 448 towards retroreflector 260 may be scattered by irregularities in the liquid caused by vortex waves, the light returns along the same path, but because the irregularities have not substantially changed on the timescale, much of the light returns to second fiber end 448 and some of that returning light is detected by photodetector 220. System 500 achieves substantially the same noise reduction as system 600.

[0076] An exemplary threshold level 900 is shown in the plot of Figure 9. The data in Figure 9 shows that evaporation has not yet terminated, resulting in a decrease in signal level after crossing threshold level 900. If evaporation had terminated, the signal level would have decreased or remained constant after crossing threshold level 900.

[0077] The signal data may be processed to determine a running average for comparison to a threshold level to determine whether to terminate evaporation, or more generally, to determine when the liquid level has reached a predetermined level in the sample container relative to the position of the optical fiber assembly, particularly the position of optical fiber end 448, and in the case of system 400, the position of fourth optical fiber end 464.

[0078] This patent disclosure includes the following examples. [Example]

[0079] Example 1. An evaporation device for evaporating a portion of a liquid in a sample container, the evaporation device comprising: a sample holder for holding a sample container; A light source and a photodetector configured to output an electronic signal indicative of a characteristic of light received by the photodetector; an optical fiber assembly configured to transmit light emitted by the light source along an optical path through at least a portion of the sample container when disposed in the sample holder and to transmit light that has traveled along the optical path to a photodetector; an evaporation device comprising: a controller in electrical contact with the photodetector, the controller configured to obtain an electronic signal and control the evaporation device to terminate evaporation based on the electronic signal.

[0080] Example 2. The evaporation apparatus of example 1, wherein the optical path is offset relative to the central longitudinal axis of the sample vessel when placed in the sample holder.

[0081] Example 3. The evaporation device of example 1 or 2, further comprising a retroreflector comprising a reflective surface disposed at an end of and toward the light path.

[0082] Example 4. The evaporation apparatus of example 3, wherein the retroreflector is positioned such that when the sample container is placed in the sample holder, light passing through the sample container is reflected in the opposite direction along the optical path.

[0083] Example 5. An optical fiber assembly comprising: receiving the light emitted by the light source, emitting at least a portion of the received light emitted by the light source along a light path along which at least a portion of the sample container can be positioned; Receives light that has traveled along the optical path, 10. The evaporation device of any one of the preceding embodiments, configured to emit at least a portion of the received light that has traveled along the optical path towards the photodetector.

[0084] Example 6. An optical fiber assembly comprises one or more optical fibers comprising a first optical fiber end, a second optical fiber end, and a third optical fiber end, wherein the one or more optical fibers are: a first optical fiber end positioned to receive light emitted by the light source; a second optical fiber end positioned to emit at least a portion of the received light emitted by the light source along the optical path; and 6. The evaporation device of example 5, wherein the third optical fiber end is positioned to emit at least a portion of the received light that has traveled along the optical path toward the photodetector.

[0085] Example 7. The evaporation device of example 6, according to one of examples 3 or 4, wherein a retroreflector is disposed opposite the second optical fiber end of the one or more optical fibers, the retroreflector being configured to reflect light emitted by the second optical fiber end toward the second optical fiber end.

[0086] Example 8. The one or more optical fibers comprise a first optical fiber comprising a first optical fiber end, a second optical fiber end, and a third optical fiber end; 8. The evaporation apparatus of example 6 or 7, wherein the first optical fiber comprises an optical splitter, a first fiber light path through the first optical fiber proceeding from the first optical fiber end to the second optical fiber end through the optical splitter, and a second fiber light path proceeding from the second optical fiber end to a third optical fiber end through the optical splitter.

[0087] Example 9. A controller includes a processing circuit including a processor and a memory, the processing circuit being in electrical contact with the photodetector, and the processor and memory: an acquisition module configured to acquire an electronic signal from the photodetector; a decision module configured to decide whether to terminate evaporation based on the acquired electronic signal; 10. The evaporation device of any one of the preceding examples, comprising: a termination module configured to terminate evaporation when the decision module determines to terminate evaporation.

[0088] Example 10. The evaporation device of any one of the preceding examples, wherein the characteristic characteristic of the light received by the photodetector comprises at least one of light intensity, a change in light intensity, wavelength, a change in wavelength, polarization, and a change in polarization.

[0089] Example 11. The characteristic property is light intensity or a change in light intensity, Preferably, the controller is configured to control the evaporation device to terminate evaporation when the electronic signal indicates that the light intensity or change in light intensity is above or below a threshold light intensity or change in light intensity, respectively.

[0090] Example 12. The evaporation device comprises at least one nozzle, the sample holder is configured to hold the sample container in a defined position relative to the at least one nozzle, and the evaporation device is configured such that a gas flow is supplied through the at least one nozzle so that a vortex is formed in the liquid to be evaporated in the sample container when the evaporation device is in use; The evaporation device of any one of the preceding embodiments, wherein the controller is configured to control the evaporation device to terminate evaporation by terminating gas flow to the sample container.

[0091] Example 13. A sample holder is provided with a heatable liquid tank, and when the heatable liquid tank contains a liquid, the sample holder is positioned such that the sample container is at least partially immersed in the liquid in the heatable liquid tank when placed in the sample holder, and the light source, light detector, and controller are positioned outside the heatable liquid tank; The evaporation device of any one of the preceding embodiments, wherein the controller is configured to control the evaporation device to terminate evaporation by terminating heating of the heatable liquid reservoir.

[0092] Example 14. the optical path is correlated to a predetermined liquid level in the sample container where evaporation is terminated; and / or the light source is configured to emit light having a wavelength in the range of 650 to 1000 nm, preferably 700 to 980 nm, more preferably 750 to 950 nm; and / or The evaporation apparatus of any one of the preceding embodiments, wherein the photodetector comprises a phototransistor or a photodiode.

[0093] Example 15. A method for evaporating a portion of a liquid evaporating in a sample container, the method comprising: Evaporating the liquid in the sample container; transmitting light from the light source along an optical path through at least a portion of the sample container using an optical fiber assembly; transmitting the light through the optical path to a photodetector; generating, by the photodetector, an electronic signal indicative of a characteristic of the light detected by the photodetector; and terminating evaporation based on the electronic signal.

[0094] While this patent disclosure refers to particular examples which are also illustrated in the accompanying drawings, it will be apparent to those skilled in the art that many variations and modifications can be made within the scope of the disclosure as described herein and defined by reference to the claims.

Claims

1. An evaporation device for evaporating a portion of a liquid in a sample container, the evaporation device comprising: a sample holder for holding the sample container; A light source and a photodetector configured to output an electronic signal indicative of a characteristic of light received by the photodetector; an optical fiber assembly configured to transmit light emitted by the light source along an optical path through at least a portion of the sample container when disposed in the sample holder and to transmit light that has traveled along the optical path to the photodetector; a controller in electrical contact with the photodetector, the controller configured to acquire the electronic signal and control the evaporation device to terminate evaporation based on the electronic signal; a retroreflector having a reflective surface disposed at an end of and toward the optical path.

2. 2. The evaporation device of claim 1, wherein the optical path is offset relative to a central longitudinal axis of the sample vessel when placed in the sample holder.

3. 3. The evaporation device of claim 1, wherein the retroreflector is a microcube corner retroreflector.

4. 4. The evaporation device of claim 1, 2, or 3, wherein the retroreflector is positioned such that when the sample vessel is placed in the sample holder, light passing through the sample vessel is reflected in the opposite direction along the optical path.

5. The optical fiber assembly receiving light emitted by the light source; emitting at least a portion of the received light emitted by the light source along the optical path in which at least a portion of the sample container can be positioned; receiving light that has traveled along the optical path; and 10. An evaporation device according to any one of the preceding claims, configured to emit at least a portion of the received light that has travelled along the optical path towards the photodetector.

6. the optical fiber assembly comprises one or more optical fibers having a first optical fiber end, a second optical fiber end, and a third optical fiber end, the one or more optical fibers comprising: the first optical fiber end is positioned to receive light emitted by the light source; the second optical fiber end is positioned to emit at least a portion of the received light emitted by the light source along the optical path; and 6. The evaporation device of claim 5, wherein the third optical fiber end is positioned to emit at least a portion of the received light that has traveled along the optical path toward the photodetector.

7. 7. The evaporation device according to claim 6, wherein the retroreflector is arranged opposite the second optical fiber end of the one or more optical fibers, the retroreflector being configured to reflect light emitted by the second optical fiber end towards the second optical fiber end.

8. the one or more optical fibers comprising a first optical fiber comprising the first optical fiber end, the second optical fiber end, and the third optical fiber end; 8. The evaporation device of claim 6 or 7, wherein the first optical fiber comprises an optical splitter, a first fiber optical path through the first optical fiber proceeding from the first optical fiber end to the second optical fiber end via the optical splitter, and a second fiber optical path proceeding from the second optical fiber end to the third optical fiber end via the optical splitter.

9. the controller comprises a processing circuit including a processor and a memory, the processing circuit being in electrical contact with the photodetector, the processor and the memory configured to: an acquisition module configured to acquire the electronic signal from the photodetector; a decision module configured to decide whether to terminate evaporation based on the acquired electronic signal; 10. The evaporation device of any one of the preceding claims, comprising: a termination module configured to terminate evaporation if the decision module determines to terminate evaporation.

10. 10. The evaporation device of any one of the preceding claims, wherein the characteristic properties of the light received by the light detector comprise at least one of light intensity, change in light intensity, wavelength, change in wavelength, polarization, and change in polarization.

11. the characteristic characteristic is light intensity or a change in light intensity; 11. The evaporation device of claim 10, wherein the controller is preferably configured to control the evaporation device to terminate evaporation when the electronic signal indicates that the light intensity or the change in light intensity is above or below a threshold light intensity or change in light intensity, respectively.

12. the evaporation device comprises at least one nozzle, the sample holder is configured to hold the sample container in a defined position relative to the at least one nozzle, and the evaporation device is configured such that a gas flow is supplied through the at least one nozzle so that a vortex is formed in the liquid to be evaporated in the sample container when the evaporation device is in use; 10. The evaporation device of any one of the preceding claims, wherein the controller is configured to control the evaporation device to terminate evaporation by terminating gas flow to the sample vessel.

13. a heatable liquid tank, wherein when the heatable liquid tank contains liquid, the sample holder is positioned such that the sample container is at least partially immersed in the liquid in the heatable liquid tank when placed in the sample holder, and the light source, the light detector, and the controller are positioned outside the heatable liquid tank; 10. An evaporation device according to any one of the preceding claims, wherein the controller is configured to control the evaporation device to terminate evaporation by terminating heating of the heatable liquid reservoir.

14. the optical path is correlated to a predetermined liquid level in the sample vessel at which evaporation ends, and / or the light source is configured to emit light having a wavelength in the range of 650 to 1000 nm, preferably 700 to 980 nm, more preferably 750 to 950 nm; and / or 10. The evaporation device of any one of the preceding claims, wherein the photodetector comprises a phototransistor or a photodiode.

15. 1. A method for evaporating a portion of a liquid evaporating in a sample container, the method comprising: Evaporating the liquid in the sample container; transmitting light from a light source along an optical path through at least a portion of the sample vessel using an optical fiber assembly; transmitting the light that has passed through the optical path to a photodetector; generating, by the photodetector, an electronic signal indicative of a characteristic of the light detected by the photodetector; terminating evaporation based on the electronic signal.

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