Introduction of crosstalk circuit for improving sensor linearity

Abstract

An optical sensor includes a detector having a printed circuit board (RGB) and a sense loop. The printed circuit board (RGB) has a photodiode cathode pad with a photodiode. The sense loop is disposed around at least a portion of the photodiode cathode pad and is configured to receive sense loop introduction signaling and provide sense loop signaling around at least a portion of the photodiode cathode pad to provide a sense on the RGB to reduce or substantially eliminate unwanted electrical interference in electrical photodiode signaling provided from the photodiode. The sense loop includes a trace and at least one via. The trace has a routing along a signal path from a transistor collector leg around an LED anode pad. The at least one via is placed between the LED anode pads to route the trace on a top side of the RGB and the trace is routed alongside, near, and around the photodiode cathode pad back to an LED anode of the LED anode pad.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims the benefit of provisional patent application serial number 63 / 135,799 (911-023.12-2 / N-YSI-0050US01) filed January 11, 2021, which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present invention relates to an optical sensor such as a fluorometer; and more particularly, to an optical sensor having a printed circuit board (PCB) with a photodiode cathode pad along with a photodiode. BACKGROUND

[0004] In the prior art, environmental sensing faces two industry trends that are in conflict with each other:

[0005] 1) The most advanced sensor technology is trending towards smaller and smaller sizes, which creates undesirable effects such as electrical cross-talk, and

[0006] 2) The demand for environmental sensing requires increasing sensitivity, which exacerbates the problems associated with cross-talk.

[0007] As a result: cross-talk is unavoidable despite best efforts to execute best practices in PCB layout.

[0008] In addition, there is also a high variability in the amplitude and introduced phase shift caused by cross-talk in known sensor technology. Furthermore, the electrical cross-talk amplitude and phase shift are not perfect fixed, indivisible system constants that are unaffected by the external environment, but exhibit a non-negligible sensitivity to the circuitry they are interfacing with. For the current case, a collection of prototype sensors were all tested with multiple signal output adapters (SOAs) to check for variability. This effect has undesirable consequences for the efficiency of the correction signal processing. In particular, the signal phase used as one of the inputs to the signal processing is susceptible to phase noise, especially when trying to resolve the phase of very low signal amplitudes, which is often the case for electrical cross-talk signals. While a very small cross-talk signal is acceptable (as this would indicate negligible electrical cross-talk), it is more common that the cross-talk signal is small enough in amplitude to be susceptible to phase noise, producing a noisy correction input, but still large enough to impede the required signal linearity. Finally, the variability in the introduced phase shift also presents a problem. For the most stable correction signal processing, a 90-degree phase shift is optimal, but in practice, the resulting phase shift introduced by cross-talk can range anywhere between (-10 to +180) degrees, with amplitudes ranging from 0.1% to 20% of the available analog-to-digital converter range, for example Figure 1The multiple points of each of the six (6) prototypes shown therein represent the unique response of the prototype to different signal output adapters.

[0009] In Figure 1 In the plot in FIG. 2, the delta phase is the relative phase shift of the crosstalk signal with respect to the excitation LED signal, and the optical dark amplitude is the amplitude of the crosstalk signal in the absence of any optical signal. The correction signal processing is unaffected / unchanged with respect to changes in the optical dark amplitude (except for the requirement that the optical dark amplitude be large enough to resolve its phase adequately). However, this is not the case for the delta phase, because once this parameter is set to a calibration constant, any change in this parameter will result in a correction error, e.g., consistent with that set forth herein. SUMMARY

[0010] As an example and in accordance with some embodiments, the present application provides two new and unique inventions for implementation in a new and unique optical sensor that addresses and solves the above-mentioned problems in the prior art.

[0011] The first invention provides a new and unique correction signal processing algorithm, e.g., referred to herein as Optical Sensor with Signal Processing to Correct Electrical Interference (Xylem no. N-YSI-0039), that implements an internal / self-linear correction of the optical sensing in conjunction with real-time amplitude and phase information. Specifically, any unwanted electrical crosstalk combined with the desired optical signal results in distortions on the amplitude and phase information, causing signal non-linearity. However, these distortions are complementary (i.e., meaning their relationship is interdependent), which allows the amplitude and phase information to be combined in a unique way to extract the desired pure optical signal, e.g., also by using the second invention consistent with that set forth herein.

[0012] In addition, the second invention mitigates certain vulnerabilities present in the correction signal processing algorithm disclosed herein in relation to the first invention, e.g., by intentionally introducing a modest induced crosstalk with an optimal phase shift at a specific location on the PCB (Xylem no. N-YSI-0050). As an example and in accordance with some embodiments, the present invention introduces a sensing loop in relation to an electrical component on the PCB of the optical sensor, e.g., a photodiode cathode leg of a photodiode such as the PCB.

[0013] Note that the correction signal processing algorithm can be used with or without a sensing loop, as long as the interfering electrical crosstalk signal has sufficient amplitude and resolvable phase. However, the sensing loop does intentionally increase the crosstalk amplitude, allowing for a more resolvable phase determination and with a “forced” optimal phase shift, i.e., the sensing loop enhances the efficiency of the correction signal processing algorithm.

[0014] Particular embodiments

[0015] According to some embodiments, the invention can comprise or take the form of a device such as a fluorometer having an optical sensor with a detector comprising a printed circuit board (PCB) and a sense loop.

[0016] As an example, the PCB can comprise a photodiode cathode pad with a photodiode, and the sense loop can be arranged around at least a portion of the photodiode cathode pad and configured to: receive sense loop introduction signaling, and provide sense loop signaling around the at least a portion of the photodiode cathode pad to provide inductive crosstalk on the PCB to reduce or substantially eliminate unwanted electrical interference in electrical photodiode signaling provided from the photodiode.

[0017] The device can comprise one or more of the following additional features:

[0018] The sense loop can comprise: a trace having a routing along a signal path from a transistor collector pin around a LED anode pad; and at least one via placed between the LED anode pads to route the trace on a top side of the PCB, the trace being routed alongside, near, and around the photodiode cathode pad, back to the LED anode of the LED anode pad.

[0019] The at least one via can comprise a further via placed along the routing around the photodiode cathode pad, the further via being configured to skip a further 2.5V bias connection formed with a further component on the PCB.

[0020] The sense loop can be a 3 / 4 sense loop around the photodiode cathode pad.

[0021] The device can comprise or take the form of a fluorescence-based optical sensor or fluorometer configured to provide an optical-based water quality sensor.

[0022] The photodiode can be configured to: receive light emission signaling L em emitted by one or more fluorescent substances of interest, and provide electrical photodiode signaling having an electrical current or photodiode current, the electrical current or photodiode current containing information about the one or more fluorescent substances of interest in the liquid related to a liquid parameter of interest in the liquid.

[0023] The optical sensor can comprise a signal processor or processing module for implementing a correction signal processing algorithm, e.g., the signal processor or processing module is configured to at least:

[0024] Receive and process electrical photodiode signals, which have amplitude and phase components; and

[0025] Provides optical sensor signaling with combined real-time amplitude and phase linear correction, for example to reduce or substantially eliminate unwanted electrical interference in electrical photodiode signaling.

[0026] Electrical photodiode signaling can use the total measurement signal S tot The form of the total measurement signal S tot It is the first contribution A o In addition to the second contribution The sum of, of which

[0027] First Contribution A o It originated from optics and has the first signal amplitude A. o Furthermore, it is independently known that the fluorescent substance in the liquid exhibits a purely linear response, and

[0028] Second contribution It has a second signal amplitude A e Electrical interference signal, second signal amplitude A e It is constant and independent of the analyte, and has a generally constant phase shift relative to the first contribution. .

[0029] The signal processor or processing module can be configured to at least:

[0030] Identifying the total signal S tot The real and imaginary parts are used to derive:

[0031] as well as

[0032] By replacing the real and imaginary parts, the amplitude M and phase Φ can be constructed as follows:

[0033]

[0034] The signal processor or processing module is configured to at least:

[0035] By eliminating the amplitude A of the second signal e , to bring A o The determination is as follows:

[0036]

[0037] In order to provide A o The algebraic derived expression, A ois the part of the signal that has a pure linear response to the concentration of the fluorescent substance optically predicted.

[0038] Alternative embodiments

[0039] According to some embodiments, the invention can also take the form of an optical sensor with a detector having a printed circuit board (PCB), and having a signal processor or processing module.

[0040] The printed circuit board (PCB) can include a photodiode cathode pad with a photodiode for receiving a light emission signaling L em and providing electrical photodiode signaling having an electrical current or photodiode current containing information about the fluorescent substance of interest in the liquid related to the liquid parameter of interest.

[0041] The signal processor or processing module can be configured to at least:

[0042] receive and process the electrical photodiode signaling having an amplitude magnitude and a phase component; and

[0043] provide optical sensor signaling having combined real-time amplitude and phase linear corrections.

[0044] The optical sensor can also include one or more of the features set forth above and herein.

[0045] Method

[0046] According to some embodiments, and as a further example, the invention can include a method characterized by the steps of:

[0047] configuring an optical sensor with a detector having a printed circuit board (PCB), the printed circuit board (PCB) having a photodiode with a photodiode cathode pad;

[0048] arranging an inductive loop around at least a portion of the photodiode cathode pad;

[0049] receiving in the inductive loop inductive loop introduction signaling; and

[0050] providing inductive loop signaling around the at least a portion of the photodiode cathode pad to provide inductive crosstalk on the PCB to reduce or substantially eliminate unwanted electrical interference in electrical photodiode signaling provided from the photodiode.

[0051] The method can also include one or more of the features set forth above.

[0052] Computer-readable storage medium

[0053] According to some embodiments, and by way of further example, the application can also take the form of a computer-readable storage medium having computer-executable components for performing the steps of the aforementioned method. The computer-readable storage medium can also include one or more of the features set forth above.

[0054] Further alternative embodiments

[0055] According to some embodiments, and by way of further example, the application can include or take the form of an optical sensor having a printed circuit board (PCB) and a sense loop.

[0056] The printed circuit board (PCB) can include an opto-electrical component configured to sense an optical signal and provide electrical signaling containing information about the sensed optical signal.

[0057] The sense loop can be arranged around at least a portion of the opto-electrical component and configured to receive sense loop introduction signaling and provide sense loop signaling around at least a portion of the opto-electrical component to provide inductive crosstalk on the PCB to reduce or substantially eliminate unwanted electrical interference in the electrical signaling provided from the opto-electrical component.

[0058] By way of example, the opto-electrical component can include a photodiode cathode pad with a photodiode; and the sense loop is arranged around at least a portion of the photodiode cathode pad. BRIEF DESCRIPTION OF DRAWINGS

[0059] The accompanying drawings are not necessarily drawn to scale, include Figures 1-11 As follows:

[0060] Figure 1 is a plot of incremental phase (degrees) versus optical dark amplitude and shows the variation in the incremental phase parameter that results in signal correction instability.

[0061] Figure 2 includes Figure 2 A and Figure 2 B, which shows a graphical illustration of the two main forms of crosstalk - capacitive crosstalk and inductive crosstalk.

[0062] Figure 2 is a photograph of a PCB that has been hand modified, e.g., to introduce a single sense loop in accordance with the application.

[0063] Figure 3 includes Figure 4 A (before) and Figure 4B (after), e.g., showing an electrical schematic of a deliberately introduced, manually modified, sensing loop according to the present application.

[0064] Figure 4 is a plot of the incremental phase (degrees) versus the optical dark amplitude, and shows the change in sensor performance before and after introducing a sensing loop in Figure 3

[0065] Figure 6 includes Figure 6 A and 6B, showing the PCB layout before and after deliberately introducing a 3 / 4 sensing loop in Figure 6 B according to the present application.

[0066] Figure 7 is a plot showing the conceptual layout of a linearization detection scheme, e.g., according to some embodiments of the present application.

[0067] Figure 8 is a plot of the amplitude, signal phase, and concentration, showing a plot of the raw amplitude and signal amplitude used in the derived amplitude and phase combination, e.g., according to some embodiments of the present application.

[0068] Figure 9 is a plot of the signal phase versus the concentration, showing a plot of the superimposed uncorrected and corrected electrical-optical signal for comparison, where the total signal contains both the optical background signal and the electrical background signal (uncorrected amplitude), and where the extracted optical portion of the signal is linear with the measurand (corrected amplitude).

[0069] Figure 10 is a flowchart showing the detailed description for determining the unique amplitude and phase combination, e.g., including the physical model, the measurements of the amplitude and phase, the mathematical manipulations, and the combination of the system-specific amplitude and phase.

[0070] Figure 11 is a block diagram of an apparatus, e.g., including a fluorometer, according to some embodiments of the present application, the apparatus including an optical sensor having a detector.

[0071] To reduce clutter in the figures, each figure in the figures does not necessarily include every reference numeral of every element shown in the figure. DETAILED DESCRIPTION

[0072] SUMMARY OF THE BASIC INVENTION

[0073] ​In general, the present invention mitigates the vulnerability in the correction signal processing algorithm by intentionally introducing a modest inductive crosstalk with an optimal phase shift at a specific location on the PCB. For example, if the crosstalk signal is large enough (but not too large) in amplitude (approximately 2-5% of the available ADC range), then the corresponding signal phase will be well resolved and a stable input will be provided into the correction signal processing. The question is: where is the ideal location to intentionally introduce the crosstalk? As an example and in accordance with some embodiments, the present invention provides a photodiode as the ideal location to intentionally introduce the crosstalk because it is the most critical component in the receiving side of the circuit (receiving side - means any and all circuitry that is dedicated to receiving and propagating electro-optical signals). The photodiode receives the optical light and returns a current called the photocurrent. Any crosstalk located downstream in the signal chain of the photodiode or receiving electronics will cause signal nonlinearity. The next question is: what type of crosstalk should be intentionally employed? For example, the crosstalk can manifest itself in two main forms: 1) capacitive crosstalk mediated by electric fields, and 2) inductive crosstalk mediated by magnetic fields, for example, as shown in Figure 2 In the terminology of electrical crosstalk, the "driver" is the wire that initiates the crosstalk, and the "victim" is the line or component that is susceptible to the initiated crosstalk.

[0074] To perform a proof of concept, a single inductive loop was introduced by lifting the cathode leg of the LED and soldering a series electrical jumper around the photodiode cathode leg before terminating on the LED cathode pad. As an example and in accordance with some embodiments, the present invention is based on providing inductive crosstalk because it is relatively simple to implement in practice (i.e., easy to perform a manual modification) and provides the optimal +90 degree phase shift, (see Figure 2 ).

[0075] With the introduction of the inductive loop, the delta phase exhibited a greatly enhanced stability because the delta phase parameter was very close to the optimal 90 degrees, and showed minimal variation across multiple signal output adapters. As expected, the optical dark amplitude fell approximately within the required 2-5% of the available ADC range, and this parameter was not significantly affected because it had no specific dependency in the correction signal processing.

[0076] In accordance with further details set forth below, the present invention also provides and utilizes a correction signal processing algorithm entitled "Optical Sensor with Signal Processing for Correcting Electrical Interference", for example, which algorithm is based on using equation (4):

[0077] Equation 4)

[0078]

[0079] where A o is the linear (optical) part of the signal

[0080] (incremental phase), is a system constant

[0081] θ signal phase, real-time, measured input

[0082] M signal amplitude, also real-time, measured input

[0083] A e (optical dark amplitude), not a key element in the correction signal processing

[0084] A key element of one aspect of the invention is the intentional introduction of a sense loop, for example around the photodiode cathode leg of the photodiode.

[0085] As an example, Figure 6 B illustrates a PCB layout as one possible embodiment of a sense loop. This layout will provide consistent sensing (as opposed to a hand-modified loop).

[0086] For example, the PCB modification can be achieved by intentional PCB layout by wiring trace T from the PNP transistor collector pin (U21 in schematic ( Figure 4 ) in the LED anode pad (DS1 in schematic ( Figure 4 ) around, and placing vias (e.g., a via is an electrical connection between board layers) between the DS1 pads to make the wiring on the top of the PCB. From there, trace T can be wired as close as possible alongside the photodiode cathode pad (PD1 in schematic ( Figure 4 ). Along the wiring around the photodiode cathode pad, place vias to jump the other 2.5V bias connections made to other components. In total, ¾ of the sense loop can be completed around the PD1 cathode pad before the LED anode is finally connected back to the DS1 pads.

[0087] Correction signal processing algorithm for correcting electrical interference in an optical sensor

[0088] Another problem to be solved by the invention

[0089] Physical systems are often inherently nonlinear in nature, i.e., the output or response of the system is often not simply proportional to the stimulus or input as one might desire (see Liu Z, Huang D, Xing Y, Zhang C, Wu Z, Ji X., entitled "New trends in nonlinear control systems and applications", Abstr Appl Anal. 2015; 2015: 2). To accommodate real systems, the trend in sensing technology is to expand its scope. Instead of performing only one type of measurement on one physical parameter, progress is being made in measuring and utilizing any and all available physical information to make informed decisions. (See, e.g., https: / / hbr.org / 2014 / 11 / how-smart-connected-products-are-transforming-competition.) The present disclosure embodies the spirit conveyed in the preceding statement.

[0090] The general topic of nonlinear physical systems is too broad to convey the advantages of the present invention, which focuses on a related class of physical systems involving optical-based water quality sensing. The operational principle of optical-based water quality sensors can most generally be described as converting light / material interactions into electrical signals, which are typically composed of current or voltage. State-of-the-art sensor technology relies on increasingly smaller circuitry, which requires that the electrical sensitive elements (e.g., sensitive receiver electronics) must be placed in close proximity to electrical noise elements that generate unwanted electrical interference (or crosstalk). (See, e.g., http: / / www.analog.com / media / en / training-seminars / design-handbooks / Basic- Linear-Design / Chapter 12.pdf.) Despite efforts to perform best practices in modern electrical design, optical sensing technology remains susceptible to electrical interference, resulting in signal nonlinearities. At the same time, the demand for environmental sensing requires increasing sensitivity, exacerbating the problems associated with nonlinearities. (See, e.g., Michael J. McGrath, Cliodhna Ni Scanaill, Dawn Nafus, Sensors Technology: Healthcare, Health and Environmental Applications, paperback.) Electrical signals (current or voltage) have both amplitude (broadly, magnitude) and phase (a specific point or stage in the cycle progression). Unwanted electrical interference combines with the desired optical signal, causing distortions in both amplitude and phase information. However, these distortions are complementary, which in turn allows the amplitude and phase information to be combined in a unique way to extract the desired linear portion of the signal. While current technology is capable of measuring both amplitude and phase simultaneously, existing sensors typically utilize either the amplitude or the phase, but not both. Moreover, the inventors are aware of no existing technology that employs the combined use of both the amplitude and the signal phase to achieve linear correction.

[0091] Solution to the problem

[0092] Another aspect of the present invention enables internal / self-linear correction of fluorescence-based sensors exhibiting nonlinear responses by uniquely combining real-time amplitude and phase information, such as by implementing the correction signal processing algorithm set forth below. To determine the system-specific amplitude and phase information, the present invention employs physics-based modeling as a guide. The modeling establishes the correct mathematical arrangement of signal contributions, and once determined, the desired linear contribution can be mathematically extracted (i.e., solved) from the total signal, generating the correct combination (or formula) of amplitude and phase required to achieve linearity.

[0093] Fluorescence-based sensing uses a light source (e.g., at a specified optical wavelength) to optically excite a fluorescent substance of interest, which then re-emits optical light specific to the water parameters of interest (e.g., at a longer optical wavelength). For a physical system consisting of a fluorometer and electrical interference, the total measurement signal S tot It can be modeled as the sum of contributions from all known signals. The first contribution originates from optics, with a signal amplitude A. o It is independently known (a priori) that the fluorescent substance has a purely linear response to its concentration. The second contribution is the electrical interference signal, whose amplitude A e It is constant and independent of the measured object, and it is also known (a priori) to have a generally constant phase shift with respect to the optical contribution. . Figure 7 The conceptual layout of the linear extraction scheme is shown. These signals can be mathematically represented as:

[0094]

[0095] Identifying the total signal S tot By taking the real and imaginary parts, we get:

[0096]

[0097] The amplitude M and phase Φ are constructed as follows:

[0098]

[0099] The explicit forms of the real and imaginary parts in Equation 2) can be substituted into Equation 3, where the optical amplitude A o It can be solved algebraically, as shown in Equation 4 below. A corollary of this particular example is that the amplitude A of the electrical background... e It can be algebraically decomposed / eliminated and will not appear in the final expression.

[0100]

[0101] Equation 4 is A o The algebraic derived expression, A o This is the portion of the signal that exhibits a purely linear response to the concentration of the fluorescent substance (as predicted by optics). Note that Equation 4 depends only on the measured signal amplitude, the measured signal phase Φ, and the relative phase shift. Relative phase shift It is a measurable constant and can be stored in system calibration. Note that the specific functional form of Equation 4 is unique for the specific physical system described above. Regarding... Figure 10 The description further details the use of a corrected signal processing algorithm to determine a unique combination of amplitude and phase.

[0102] BelowFigure 9 and Figure 8 The data presented in FIGS. 1-3 represent a real-world implementation of the present application applied to a fluorescence-based sensor. For this data, serial dilutions were performed to vary the concentration of a selected fluorescent species, with the amplitude and phase response at each concentration being recorded. Figure 9 The raw amplitude and signal amplitude input to the derived amplitude and phase combination are shown and disclosed, and Figure 10 The overlapping uncorrected vs. corrected electro-optical signals are shown and disclosed for comparison.

[0103] Regarding the overall sensor layout: the sensor according to the present application differs from a conventional fluorometer primarily in the details relating to the electrical signal chain and the specific operations applied to the measured amplitude and signal phase. The spirit of the present application is not limited to any particular hardware performing the measurements of amplitude and signal phase, nor is it intended to be limited to any particular type of signal interference (in this example, electrical interference) is identified. Furthermore, the present application is not intended to be limited to any particular hardware (e.g., a microprocessor or field programmable gate array (FPGA) can be used) to perform the operations necessary to achieve a uniquely determined amplitude and phase combination.

[0104] Figure 10

[0105] Figure 11 A flowchart 100 is shown with steps 100a, 100b, 100c, and 100d for determining a unique amplitude and phase combination using a correction signal processing algorithm, e.g., a physical model 100a, a measurement of amplitude and phase 100b, mathematical manipulation 100c, and a system-specific amplitude and phase combination 100d are shown.

[0106] In the physical model step 100a, e.g., f n is the nth signal contribution, and a m is the mth independent parameter. Independent parameters include, but are not limited to: amplitude, time, frequency, initial and constant phase shift, measured concentration, etc. Note that model-based approaches can predict functional forms other than a simple summation of signal contributions. For example, depending on the particular physical system at hand, the model can predict a product of a series of functions or other forms. Further note that the quality of the extracted linear signal can be only as good or effective as the physical model used to derive the amplitude and phase combination. Any unaccounted for contributions to the signal can introduce errors in the final extracted value.

[0107] For example, in the measurement of amplitude and phase step 100b, the spirit of the present application is not limited to any particular hardware used to perform the measurement of signal amplitude or signal phase.

[0108] In the mathematical manipulation step 100c, for example, for the example listed herein, only direct algebra is required to isolate the desired variable. The spirit of the invention is not intended to be limited to the use of any particular mathematical tool required to extract a linear component from an otherwise non-linear signal. In general, techniques involving calculus, Fourier analysis, linear algebra, correlation or convolution or any other mathematical tool can be used as required to isolate the desired parameter.

[0109] In the system-specific amplitude and phase combination step 100d, for example, the final expression of the desired combination can necessarily have the following property: the desired variable must ultimately be expressible in terms of the measured amplitude M and the measured signal phase Φ and any identified system constants applicable to the system calibration. Important note: not all physical systems are necessarily solvable. Furthermore, not all solvable systems can be expressed in analytic form. In such cases, for example, it can be required to express the solution in a series expansion or product expansion to the desired order. Important corollary: the disclosed method also allows for the extraction of components other than linear contributions, for example, to identify rogue interference contributions.

[0110] Figure 11

[0111] Figure 8 A device is shown, the device comprising a fluorescence-based sensor or fluorometer 10 with an optical sensor 12, the device featuring a light source 20, a detector 30, and a signal processor or processing module 40.

[0112] The light source 20 can be configured to provide excitation light signaling L ex .

[0113] The detector 30 has a printed circuit board (PCB) 32 and a sense loop 38. The PCB 32 has a photodiode cathode pad 34 with a photodiode 36 configured to receive light emission signaling Lem emitted by a fluorescent substance of interest and to provide electrical photodiode signaling having an electrical current or photodiode current containing information of the fluorescent substance of interest in the liquid related to a liquid parameter of interest. The sense loop 38 is arranged around at least a portion of the photodiode cathode pad and is configured to receive sense loop introduction signaling and to provide sense loop signaling around at least a portion of the photodiode cathode pad to provide inductive cross-talk on the PCB to correct non-linearities in the provided electrical photodiode signaling.

[0114] The signal processor or processing module 40 is configured to at least:

[0115] receive and process the electrical photodiode signaling having amplitude and phase components; and

[0116] Optical sensor signaling is provided with combined real-time amplitude and phase linear correction to reduce or substantially eliminate unwanted electrical interference.

[0117] The signal processor or processing module 40 includes other signal processor circuitry, circuit devices or components 50 that do not form part of the underlying invention, e.g., including input / output modules / modems, one or more memory modules (e.g., RAM, ROM, etc.), data, address and control bus architecture, etc.

[0118] Implementation of signal processing functions

[0119] By way of example, the functions of the signal processor or processing module 40 can be implemented using hardware, software, firmware or a combination thereof. In a typical software implementation, the signal processor 40 will include one or more microprocessor-based architectures, e.g., having at least one signal processor or microprocessor. Those skilled in the art will be able to program with appropriate program code, such as microcontroller-based or microprocessor-based implementations, to perform the signal processing functions disclosed herein without undue experimentation.

[0120] The scope of the invention is not intended to be limited to any particular implementation using technology now known or later developed. The scope of the invention is intended to include the implementation of the functions of the signal processor as a stand-alone processor, signal processor or signal processor module and separate processor or processor module, and some combination thereof.

[0121] By way of example, the apparatus 10 can also include other signal processor circuitry or components, e.g., generally indicated as 50, including random access memory or memory modules (RAM) and / or read only memory (ROM), input / output devices and control buses and data buses and address buses connecting them, and / or at least one input processor and at least one output processor, e.g., as will be understood by those skilled in the art.

[0122] By way of further example, the signal processor 40 can include or take the form of some combination of a signal processor and at least one memory including computer program code, wherein the signal processor and at least one memory are configured such that the system implements the functions of the invention, e.g., responding to received signaling and determining corresponding signaling based on the received signaling.

[0123] Related patents

[0124] The inventors are aware of at least the following related patents, as follows:

[0125] US 2005 / 0219727 Al, entitled "Signal processing device and signal processing method".

[0126] US 6,911,925 Bl, entitled "Linearity compensation by harmonic cancellation".

[0127] US 4,968,968 A, entitled "Transmitter phase and amplitude correction for linear FM systems".

[0128] US 6,853,191 Bl, entitled "Method of removing dynamic nonlinear phase errors from MRI data".

[0129] It appears that there are several patents involving non-linear correction of amplitude and phase, but none of the known patents to the inventors disclose the present invention.

[0130] A summary of the main findings is presented below:

[0131] • The patent literature discloses distortion correction or non-linear correction applied to amplitude and phase information, but does not mention using the signal phase to correct non-linearities in the amplitude. This is a key difference between the present invention and the known inventions in the prior art patent literature.

[0132] • The patent literature mainly discloses devices or circuit designs involving electrical filters to perform the correction, rather than any complementary use of measuring the amplitude and measuring the signal phase to perform the correction.

[0133] • The patent literature discloses specific non-linearities related to magnetic and / or optical recording, correction of errors in radar systems employing FM signals, or non-linearities related to medical or MRI imaging.

[0134] Light source 20

[0135] As an example, the device 10 can comprise a light source 20 and a detector 30, the light source 20 being configured to provide light L em ( ​ ) that passes through a liquid sample arranged relative to the light source 20 and the detector 30, so as to reflect light off a fluorescent substance of interest being monitored or tested.

[0136] As will be appreciated by those skilled in the art, light sources are known in the art and the scope of the present application is not intended to be limited to any particular type or kind of light source now known or later developed.

[0137] Photodiode detector and / or sensor

[0138] With respect to sensor hardware, the photodiode detector or sensor contains elements known in the art. As an example, the sensor hardware can contain a single or multiple LED(s) appropriate for the specified excitation wavelength of the fluorescent substance of interest, and can contain one or more optical receivers (photodetectors or spectrometers) employing one or more optical bandpass filters centered spectrally at the specified excitation and / or emission wavelengths.

[0139] As will be appreciated by those skilled in the art, sensor hardware is known in the art and the scope of the present application is not intended to be limited to any particular type or kind of sensor hardware now known or later developed.

[0140] Fluorophore

[0141] As will be appreciated by those skilled in the art, a fluorophore is a fluorescent compound that can re-emit light upon excitation. Fluorophores typically contain several combined aromatic groups, or contain planar or cyclic molecules with pi-bonds.

[0142] As an example, fluorophores are sometimes used as tracers in fluids, dyes for staining certain structures, substrates or probes or indicators for enzymes (when fluorescence is affected by environmental aspects such as polarity or ions).

[0143] The scope of the present application is not intended to be limited to any particular type or kind of fluorophore now known or later developed.

[0144] Applications

[0145] The present application has applications in basic parameters of water quality monitoring, for example in fresh water applications, as well as in drinking water monitoring.

[0146] Scope of the invention

[0147] While the present application has been described with reference to exemplary embodiments, it will be apparent to those skilled in the art that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the present application. In addition, modifications can be made to adapt a particular situation or material to the teachings of the present application without departing from its central scope. Therefore, the present application is not intended to be limited to any particular embodiments disclosed herein as the best mode contemplated for carrying out this application.

Claims

1. An optical sensor with a detector, comprising: a printed circuit board having a photodiode cathode pad with a photodiode; and a sense loop disposed around at least a portion of the photodiode cathode pad and configured to receive a sense loop induced signaling and to provide a sense loop signaling around the at least a portion of the photodiode cathode pad to provide a sense crosstalk on the printed circuit board to reduce or substantially eliminate unwanted electrical interference in electrical photodiode signaling provided from the photodiode.

2. The optical sensor of claim 1, wherein the sense loop comprises: a trace having a routing along a signal path from a transistor collector leg around an LED anode pad; and at least one via placed between LED anode pads to route the trace on a top side of the printed circuit board back to an LED anode of the LED anode pads alongside, near, and around the photodiode cathode pad.

3. The optical sensor of claim 2, wherein the at least one via comprises a further via placed along the routing around the photodiode cathode pad, the further via configured to skip a further 2.5V bias connection made for other components on the printed circuit board.

4. The optical sensor of claim 1, wherein the photodiode is configured to: receive a light emission signaling L emitted by one or more fluorescent substances of interest em and provide the electrical photodiode signaling, the electrical photodiode signaling having an electrical or photodiode current, the electrical or photodiode current containing information about the one or more fluorescent substances of interest in the liquid related to a liquid parameter of interest.

5. The optical sensor of claim 4, wherein the optical sensor comprises a signal processor or processing module to implement a correction signal processing algorithm, the signal processor or processing module configured to at least: receive and process the electrical photodiode signaling, the electrical photodiode signaling having an amplitude magnitude and a phase component; and provide optical sensor signaling, the optical sensor signaling having a combined real-time amplitude and phase linear correction.

6. The optical sensor of claim 5, wherein The electrical photodiode signaling uses the total measurement signal S. tot The total measurement signal S is in the form of tot It is the first contribution A o In addition to the second contribution The sum of which the first contribution A o It originates from optics and has the first signal amplitude A. o And independently known to have a purely linear response to the concentration of the fluorescent substance in the liquid, and the second contribution It has a second signal amplitude A e The electrical interference signal, wherein the amplitude of the second signal is constant and independent of the measured object, and has an overall constant phase shift relative to the first contribution.

7. The optical sensor of claim 6, wherein the signal processor or processing module is configured to at least: identifying the real and imaginary parts of the total measurement signal S tot to obtain: and construct an amplitude M and a phase Φ by replacing the real part and the imaginary part as follows:

8. The optical sensor of claim 7, wherein the signal processor or processing module is configured to at least: by eliminating the second signal amplitude A e , to determine A o as follows: in order to have a purely linear response of the concentration of the fluorescent substance to the optical prediction of the signal for a part A of the signal o , providing an algebraic derived expression.

9. An optical sensor with a detector, comprising: Printed circuit board with a photodiode cathode pad with a photodiode for receiving a light emission signal L emitted by a fluorescent substance of interest em and providing an electrical photodiode signal having an electrical or photodiode current containing information about the fluorescent substance of interest in the liquid related to a liquid parameter of interest; and a signal processor or processing module to implement a correction signal processing algorithm, configured to at least: receive and process the electrical photodiode signaling, the electrical photodiode signaling having an amplitude magnitude and a phase component; and provide optical sensor signaling, the optical sensor signaling having a combined real-time amplitude and phase linear correction.

10. The optical sensor of claim 9, wherein The electrical photodiode signaling uses the total measurement signal S. tot The total measurement signal S is in the form of tot It is the first contribution A o In addition to the second contribution The sum of which the first contribution A o It originates from optics and has the first signal amplitude A. o And independently known to have a purely linear response to the concentration of the fluorescent substance in the liquid, and The second contribution is an electrical interference signal having a second signal amplitude A e which is constant and independent of the measurand, and has an overall constant phase shift with respect to the first contribution 11. The optical sensor of claim 10, wherein the signal processor or processing module is configured to at least: identifying real and imaginary parts of the total measurement signal S tot to obtain: and construct an amplitude M and a phase Φ by replacing the real part and the imaginary part as follows:

12. The optical sensor of claim 11, wherein the signal processor or processing module is configured to at least: by eliminating the second signal amplitude A e , to determine A o as follows: in order to have a purely linear response of the concentration of the fluorescent substance to the optical prediction of the signal for a part A of the signal o , providing an algebraic derived expression.

13. The optical sensor of claim 9, wherein the optical sensor comprises a sense loop disposed around at least a portion of the photodiode cathode pad and configured to: receive sense loop induced signaling, and provide sense loop signaling around the at least a portion of the photodiode cathode pad to provide sensing on the printed circuit board.

14. The optical sensor of claim 13, wherein the sense loop comprises: a trace having a routing along a signal path from a transistor collector leg around an LED anode pad; and at least one via placed between LED anode pads to route the trace on a top side of the printed circuit board back to an LED anode of the LED anode pad alongside, near, and around the photodiode cathode pad.

15. The optical sensor of claim 14, wherein the at least one via comprises an additional via placed along the routing around the photodiode cathode pad configured to skip an additional 2.5V bias connection formed for an additional component on the printed circuit board.

16. An optical sensor having a detector, comprising: a printed circuit board having a photoelectric component configured to sense an optical signal and provide electrical signaling containing information about the sensed optical signal; and a sense loop disposed around at least a portion of the photoelectric component and configured to: receive sense loop induced signaling, and provide sense loop signaling around the at least a portion of the photoelectric component to provide sensing on the printed circuit board to reduce or substantially eliminate unwanted electrical interference in the electrical signaling provided from the photoelectric component.

17. The optical sensor of claim 16, wherein the photoelectric component is a photodiode having a photodiode cathode pad; and the sense loop is disposed around at least a portion of the photodiode cathode pad.

18. A method for configuring an optical sensor, comprising: configuring an optical sensor having a detector with a printed circuit board having a photodiode cathode pad with a photodiode; disposing a sense loop around at least a portion of the photodiode cathode pad; receiving sense loop induced signaling in the sense loop; and providing sense loop signaling around the at least a portion of the photodiode cathode pad to provide sensing crosstalk on the printed circuit board to reduce or substantially eliminate unwanted electrical interference in electrical photodiode signaling provided from the photodiode. ​ ​

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