Potentiostat for sensing analytes

Abstract

There is provided a potentiostat (1) for sensing a presence of an analyte in a fluid sample. The potentiostat (1) has a sensor receiving region for receiving a sensor (10) which comprises a plurality of independent sensing channels each having a working electrode (WE) and a reference electrode (RE) spaced from the working electrode. The potentiostat (1) has an analog circuit provided on a first island of a printed circuit board, the analog circuit comprising: a plurality of independent analog channels, a first power supply (8) to provide voltage to the counter electrode (CE) to perform the voltametric scan; and an analog to digital converter (ADC) configured for respectively converting the plurality of voltametric signals into a plurality of digital signals. The potentiostat (1) has a digital circuit provided on a second island of the printed circuit board separate from the first island, to determine the presence of the analyte based on the digital signals as received.

Description

POTENTIOSTAT FOR SENSING ANALYTESCROSS REFERENCE TO A RELATED APPLICATION

[0001] This disclosure claims priority from U.S. provisional application number 63 / 712,698 filed on October 28, 2024, which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] This disclosure relates to the field of potentiostats for sensing analytes in body fluids, particularly that are field-deployable for on-site use or point-of-use applications such as portable devices.BACKGROUND OF THE ART

[0003] A major challenge for the implementation of potentiostats in the field of sensing analytes in body fluids of individuals is that there is a large variability in terms of properties of the body fluids for different individuals. In a laboratory setting or in a dedicated facility, calibration is possible to account for the variability between the individuals. One example of body fluids is saliva. Saliva has electrical properties (such as conductivity) that are highly unpredictable for different individuals due in part to an unknown salt content for each saliva sample and the variability between individuals. In a typical laboratory setting, the equipment operator needs to make an educated guess and set the data acquisition parameters accordingly, because the sensitivity range of a typical lab potentiostat is limited. A wrong guess results in either noisy or corrupt data, leading to the necessity of repeating the measurement with adjusted parameters. It would be desirable to have a potentiostat that can operate in the field and account for the variability between individuals. It would also be desirable for the potentiostat to be operated by anyone and not need someone specifically skilled or trained for such operations.SUMMARY

[0004] In one aspect, there is provided a potentiostat for sensing the presence of an analyte in a fluid sample. The potentiostat comprises a sensor receiving region for receiving a sensor having the fluid sample provided thereon, the sensor comprising a plurality of independent sensing channels each having a working electrode and a reference electrode spaced from the working electrode, the working electrode and the reference electrode adapted to come in contact with the fluid sample. The potentiostat also comprises an analog circuit provided on a first island of a printed circuit board. The analog circuit comprises a plurality of independent analog channelseach comprising a counter electrode where each counter electrode forms a closed electrical circuit with the working electrode and the reference electrode to perform a voltametric scan on the fluid sample and obtain a plurality of voltametric signals for each of the plurality of independent analog channels, a first power supply to provide voltage to the counter electrode to perform the voltametric scan, and an analog to digital converter (ADC) configured for respectively converting the plurality of voltametric signals into a plurality of digital signals. The potentiostat further comprises a digital circuit provided on a second island of the printed circuit board, the second island separate from the first island, the digital circuit connected to the ADC and receiving the plurality of digital signals, the digital circuit comprising a computing device configured to receive the digital signals form the ADC and to determine the presence of the analyte based on the digital signals as received and a digital to analog converter (DAC) connecting the computing device to the analog circuit for each of the plurality of independent sensing channels.

[0005] In some embodiments, the fluid sample is a body fluid, preferably saliva.

[0006] In some embodiments, the analyte is selected from the group consisting of cannabinoids, benzodiazepines, opiates, semi-synthetic opioids, synthetic opioids, steroids, narcotics, alcohols, amphetamines, arbiturates, buprenorphine, methamphetamines, cotinine, phencyclidine (PCP), 3,4-Methylenedioxy methamphetamine (MDMA), hallucinogens, ketamine, and gamma hydroxybutyrate.

[0007] In some embodiments, the ADC is a 24-bit delta-sigma ADC.

[0008] In some embodiments, the potentiostat further comprises a resistor-capacitor filter in each of the plurality of independent analog channels.

[0009] In some embodiments, the voltametric scans performed on each of the plurality of independent channels have different voltammetry profiles.

[0010] In some embodiments, the potentiostat is contained in a handheld case having a width of less than 10 cm and a length of less than 30 cm.

[0011] In some embodiments, the counter electrode comprises carbon ink or platinum.

[0012] In some embodiments, the working electrode and the reference electrode comprise silver.

[0013] In some embodiments, the analog circuit and the digital circuit are connected by a single ground connection.

[0014] In some embodiments, the voltametric scan is square wave voltammetry, cyclic voltammetry, linear sweep voltammetry, or differential pulse voltammetry.

[0015] In some embodiments, the plurality of independent sensing channels are parallel.

[0016] In one aspect, there is provided a method of sensing the presence of one more analytes in a fluid sample, the method comprising: depositing the fluid sample on the sensor region of the potentiostat as defined herein; and performing a voltametric scan on each of the plurality independent sensing channels.

[0017] In a further aspect, there is provided a method of sensing the presence of an analyte in a fluid sample, the method comprising: depositing the fluid sample on the sensor region of the potentiostat as defined herein; and performing a voltametric scan in parallel on each of the plurality independent sensing channels in parallel. In some embodiments, wherein the fluid sample is saliva.

[0018] Many further features and combinations thereof concerning the present improvements will appear to those skilled in the art following a reading of the instant disclosure.DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 is a schematic of an exemplary embodiment of the potentiostat of the present disclosure.

[0020] FIG. 2 is a schematic showing a plurality of working electrodes of the potentiostat and a plurality of channels according to one exemplary embodiment of the present disclosure.

[0021] FIG. 3 is a schematic showing a potentiostat with a plurality of channels according to one embodiment of the present disclosure.DETAILED DESCRIPTION

[0022] There is provided a potentiostat for sensing the presence of one or more analytes in a fluid sample. The analytes contemplated by the present disclosure include cannabinoids. The cannabinoid can be, for example, A9-tetrahydrocannabinol (THC), 11-hydroxy-A9-tetrahydrocannabinol (11-hydroxy-THC), delta-8-tetrahydrocannabinol (A8-THC), 11-nor-9- carboxy-tetrahydrocannabinol (11-nor-9-carboxy-THC), cannabidiol (CBD), cannabinol (CBN), and glucuronic acid conjugated COOH-THC (gluc-COOH-THC), tetrahydrocannabinolic acid (THCA) or metabolites thereof. The analyte could be an opiate which is, for example, morphine, hydromorphone and buprenorphine as well as metabolites thereof. The analyte can also be a neurotransmitter which is, for example, dopamine, serotonin, or metabolites thereof. The analyte can also be a hormone, which may be, without limitation, a steroid hormone such as, for example, estradiol, 7a-methylestradiol, or metabolites thereof. In some embodiments, the analyte is alcohol, THC, CBD or cocaine.

[0023] As will be described further below, in the illustrated embodiment, the potentiostat is a three-electrode multi-channel potentiostat which comprises a plurality of channels that each connect to a different working electrode on a sensor. The plurality of channels is for example defined as 2 or more channels, 3 or more channels, 4 or more channels, 6 or more channels, from 2 to 32 channels, from 2 to 24 channels, from 4 to 32 channels, from 4 to channels 24, from 6 to 32 channels, from 6 to channels 24, or from 6 to 12 channels. Using the multi-channel potentiostat allows to perform several electrochemical measurements simultaneously, including, but not limited to, examining the same analyte multiple times simultaneously or simultaneously quantifying multiple analytes. Any suitable number of channels may apply. In one embodiment, the potentiostat comprises six (6) channels and the sensor has six (6) working electrodes, each working electrode having an associated reference electrode and counter electrode. As understood by those skilled in the art, electrochemical reactions that are to be controlled or investigated occur at the working electrode, the reference electrode is used to deliver a constant potential (also referred to herein as an “equilibrium potential”) that keeps the voltage of the working electrode steady, and the counter electrode completes the circuit by allowing a current flow without changing the chemical composition of the fluid sample under investigation.

[0024] The potentiostat incorporates, within an analog circuit, the plurality of (e.g., six (6)) channels while still being a portable device. In one embodiment, the potentiostat has a width and a thickness of less than 10 cm each, and a length of less than 30 cm. It should however be understood that other suitable dimensions may apply, provided the potentiostat remains compact. Moreover and as will be described further below, the potentiostat includes a digital circuit (in addition to the analog circuit) within this compact configuration. The compactness of the present potentiostat allows it to be a handheld portable device that can be deployed in the field.

[0025] As previously explained, a significant advantage for a potentiostat would be to be both field deployable (such as a portable device) and to have low operation complexity such that it can be operated by any person. Existing potentiostats require a switch in sensitivity range between samples. As used herein, the term “sensitivity range” refers to the range of extreme values (e.g., minimum and maximum measurable current during voltammetry) that needs to be covered by the potentiostat for a given application. The sensitivity range of a potentiostat is the most unpredictable data acquisition parameter. In existing devices, the extreme values defining the sensitivity range of the potentiostat have to be adjusted between samples in order to enable the potentiostat to acquire a broad range of measurements (e.g., currents). In contrast, the present potentiostat has a resolution that is high enough to cover the entire range of what can be reasonably expected from a fluid sample such as a body fluid sample, in particular human saliva, thus eliminating the need to switch sensitivity range between samples. The body fluid may be saliva, milk, blood, plasma, or cerebral spinal fluid (from any animal). The sample may be a fluid other than a body fluid such as water from rivers, lakes, ponds, wetlands, or caves, and the analyte could be a contaminant in the water or a microorganism. As used herein, the term “resolution” refers to the lowest observable difference between two values that the potentiostat can differentiate between, the resolution of the potentiostat being defined by the number of bits that measurements acquired by the potentiostat are converted to. In one embodiment, the present potentiostat may achieve 16 bits of resolution. By applying a known and steady direct current (DC) voltage to the potentiostat and observing the response of the potentiostat, one would note that at least 16 bits of data are not noisy. A second different DC current value can be applied as well, and calculations can then be made to verify that each DC value is represented correctly with at least 16-bit accuracy to confirm that the potentiostat has at least 16 bits of accuracy.

[0026] The increased resolution reduces the complexity of operation and allows for nonexpert individuals to operate the potentiostat of the present disclosure. As will be described further below, the increased resolution was achieved by (1) performing an analog to digital conversion using a suitable (e.g., 24-bit Delta-Sigma) analog to digital converter (ADC), (2) signal filtering with a digital to analog converter (DAC) having built-in digital filters, (3) physically separating the analog circuitry from the digital circuitry by positioning each circuit on different areas (e.g., copper islands that are distinct) of the printed circuit board (PCB) to avoid current loops (with the analog circuitry and the digital circuitry remining connected at a single ground point), (4) adding resistor capacitor (RC) filters in the circuit path from the sensor’s working electrode to the ADC, and / or (5) providing a different dedicated power supply to the analog circuit. A gap or distance may beformed between them (e.g. moat width 0.5-1.5 mm). In some embodiments, distinct or separate PCB islands are separated by separate ground or power pours. In preferred embodiments, all of (1)-(5) are present / performed in the potentiostat. The aforementioned features allowed the potentiostat to deliver 16-bit of true data resolution (corresponding to a smallest difference between two measurements of about 0.0015% of the maximum measurement range, calculated as (1 / 2)16x 100 and was confirmed by applying a known DC value and observing that the noise stayed as less than 1 binary digit). Since the ADC delivers 24-bit values, the noise may appear in the least significant 8 binary digits to still have 16-bit resolution.

[0027] When assembling the potentiostat a major challenge was reducing the noise and interference by the proximity of the analog and digital circuits to each other. It was found that utilizing different power supplies for the analog circuit and the digital circuit reduces the noise and interference despite the proximity and improves the resolution of the potentiostat.

[0028] In addition to the above, to further improve the resolution and increase the flexibility of the potentiostat, there is optionally provided a software-controlled amplifier for facilitating switching between two or more different ranges of sensitivity (e.g., maximum and minimum measurable current during voltammetry). In one example, there can be two different ranges, one higher than the other and they can be referred to respectfully as the HI and LOW ranges. In that embodiment, the HI can for example be 10 times the value of the LOW range. In the specific embodiment where the analyte is THC, the sensitivity range can be adapted measured THC in the concentration range of 10-9ng / mL. The sensitivity range for other analytes can be in the micron range or even in the milligram. The potentiostat can have a plurality of ranges each adapted to different analytes. Another consideration is the salinity of saliva. The sensitivity range can also be selected based on the salinity of the saliva independently of the concentration of the analyte. Each sensitivity range can be quite large since a 16 bit resolution is achieved by the potentiostat. A range can for example be 3 logs (e.g. from 1 to 1000 of a particular concentration such as g / L).

[0029] Although switching between different sensitivity ranges cannot occur during the actual data acquisition phase (since this would result in data inconsistencies), the software of the software-controlled amplifier can seamlessly choose the appropriate sensitivity range of the potentiostat during a phase where no data is acquired (also referred to as a “equilibrium phase”) by observing the current flowing through the sample prior to applying the voltammetry profile. The equilibrium phase is generally a short period of time during which data collection is not performed. The equilibrium phase is generally in the order of a fraction of a second (e.g. 0.10 s, 0.20 s, 0.5 setc.). Based on the current measured, the sensitivity range can be selected to best suit the range of analyte and the type of media (e.g. salinity of the saliva). The selection of the sensitivity range does not require any input from the user. In some embodiments, the sensitivity range could be adjusted by the user, for example when changing analytes between measurements. The sensitivity can be different for each of the plurality of channels since each channel has its own amplifier for performing that switch.

[0030] In one embodiment, the potential in the voltammetry scan is in a range between 0 to 1 V. As used herein, the term “voltammetry” refers to an analytical method in which information about an analyte is obtained by measuring current as a potential is varied. In one embodiment, the potentiostat may be used to perform any suitable voltammetry technique or function including, but not limited to, cyclic voltammetry (CV), linear sweep voltammetry (LSV), differential pulse voltammetry (DPV), or square wave voltammetry (SWV).

[0031] The presence of multiple (e.g., six (6)) channels has the advantage of allowing simultaneous sensing of the same analyte multiple (e.g., six (6)) times, or offering the opportunity to sense several (e.g., up to six (6)) different analytes at the same time. In preferred embodiments, the sampling of human saliva happens on the multiple (e.g., six (6)) independent channels simultaneously. This simultaneous sensing can be done by performing the same or different voltammetry scans on each of the multiple (e.g., six (6)) working electrodes of the multiple (e.g., six (6)) independent channels. For example, the potentiostat described herein may be used to perform repeat experiments (e.g., measure the same reaction process) on multiple (e.g., six (6)) channels and obtain results that can be compared to each other to evaluate reproducibility. In addition, the potentiostat described herein may be used to perform parallel processing of measurements (e.g., for several, such as six (6) drugs) allowing to obtain results in a shorter timeframe than would be achieved using a potentiostat performing sequential processing of measurements. Accordingly, the advantage of having multiple (e.g., six (6)) channels is an increased accuracy in the sensing and / or an increase in the number of analytes that are simultaneously sensed, leading to a shorter time to result. As used herein, the term “accuracy” refers to the degree to which measurements acquired by the potentiostat are close to real (or actual) values.

[0032] However, the presence of multiple (e.g., six (6)) independent channels in a portable handheld and commercially feasible device presents several challenges. One of the difficulties is providing the multiple (e.g., six (6)) channels without introducing any channel-to-channel crosstalk(in a space limited by a handheld device). In comparison, a typical laboratory equipment analyzes multiple data channels sequentially, which not only results in longer acquisition time but produces inconsistent results due to the inconsistent time elapsed between saliva exposure and data acquisition of each sensor. Indeed, a sample sensed later than another sample is left to oxidate and would result in different electrical properties (particularly when considering a human sample such as saliva). The advantage of the present potentiostat is that, due to the multiple (e.g., six (six)) parallel and independent channels, no sample is left to oxidate.

[0033] Furthermore, the challenge to achieving increased sensitivity and resolution in a handheld device is different from the challenge of achieving same in a laboratory environment. Integration of a sensitive analog circuit and a digital computer within the same device is problematic due to electromagnetic interference. An important consideration when building the circuits is to minimize power consumption in order to emit as little heat as possible. Another important consideration is that all circuits must be able to function at high ambient temperatures (e.g. 20 to 40 °C) without external or forced cooling since a compact size is needed for field deployment. A desired feature of the device would be to be robust and not require calibration due to operating temperature fluctuations.

[0034] However, most off-the-shelf computer solutions include at least a heat sink, which is only effective when a flow of cool air is available. As this cannot be included in a handheld, weatherproof device, the reader electronics of the present potentiostat were implemented as an embedded-device. A major challenge of the potentiostat of the present disclosure is that the computing device, electrical circuitry and the detection voltammetry all create heat which is detrimental to the functioning of the device. There is an added challenge when the potentiostat is waterproof (e.g. hermitically sealed). This leads to no possibility to introduce ventilation as cooling means. Accordingly, a complex computing system such as a linux core would create too much heat and cannot be used in the potentiostat of the present disclosure. To overcome this problem, a simplified computing device was created from scratch to have only the necessary functions and computing power to avoid heating up. The internal temperature of the potentiostat and computing system preferably does not exceed 45 °C (even without cooling).

[0035] Fig. 1 shows an exemplary embodiment of the potentiostat 1 of the present disclosure. In Fig. 1 , only the operation of one channel of the potentiostat 1 is shown for simplicity, the channel comprising a number of components that will be described below (i.e. amplifiers 14, 24, and 26, switches 12, 16, and 22, and RC filters 18 and 19) and serving one biochemical sensor. However,it should be understood that, although not illustrated in Fig. 1 , the potentiostat 1 comprises a plurality of identical channels that each connect to the working electrode of a sensor. This is shown in Fig. 2, which illustrates a potentiostat with a plurality of channels as in 40. As can be seen from Fig. 2, a sensor 10 comprises a chip (not shown) having a plurality of different sensing regions (also referred to as “electrochemical cells”) 11 , each sensing region 11 connected to a different circuit of the potentiostat 1 and to a central processing unit (CPU) 30 of the potentiostat 1 in order to implement a multi-channel device. The CPU 30 may be referred to as the “digital circuit” of the potentiostat 1 while remaining components of the potentiostat 1 illustrated in Fig. 1 form the “analog circuit” referred to herein. Fig. 3 shows in more detail that each of the plurality of independent channels (reference 40 in Fig. 2) comprises a first path 50a coupling the corresponding sensing region (reference 11 in Fig. 2) to an analog to digital converter (ADC) 20, and a second path coupling the corresponding sensing region 11 to a digital to analog converter (DAC) 28, the ADC 20 and the DAC 28 electrically coupled to the CPU 30, as will be described further below.

[0036] Returning to Fig. 1 , a first power supply 8 is dedicated to supplying power for performing the voltametric scan and for powering the sensor’s counter electrode. This power supply 8 is separate from a second power supply 32 which supplies power to the CPU 30. Any suitable power supply may apply. The second power supply 32 is, for example, a rechargeable battery.

[0037] The sensor (reference 10 in Fig. 2) is separate from the potentiostat 1 and is adapted to receive multiple (e.g. six (6)) samples on each of its (e.g., six (6)) sensing regions 11. As can be seen from Fig. 2, the potentiostat 1 has a sensor receiving region (not shown) adapted to receive the sensor 10. Each of the six (6) sensing regions 11 has a working electrode (WE), a reference electrode (RE), and a counter electrode (CE) which are connected to the potentiostat 1 through connections 11a, 11 b and 11c respectively.

[0038] In operation, the CPU 30, when powered by the second power supply 32, provides a voltage waveform to the potentiostat 1 to begin voltametric sensing. For this purpose, the CPU 30 generates a digital signal which is first converted to an analog signal by the DAC 28. The DAC 28 is preferably a 16-bit DAC. It should however be understood that the DAC 28 may have any suitable bit depth other than 16. The DAC 28 also has digital filters built therein to further reduce noise in the signal. The analog signal generated by the DAC 28 is then provided to an input of a control amplifier 26, which is used to control the reference electrode potential. For this purpose,the reference electrode is connected (via connection 11b) to an input terminal (not shown) of the control amplifier 26 and the control electrode is connected (via connection 11c) to the output terminal (not shown) of the control amplifier 26. The control amplifier 26 provides, at its output terminal and via switch 22, an output voltage to the control electrode for adjusting the potential on the control electrode until the voltage of the reference electrode attains a desired value.

[0039] Still referring to Fig. 1 , a unity gain amplifier 24 (also referred to herein as a reference electrode amplifier) is connected between the reference electrode and the control amplifier 26, forming a negative feedback loop for the control amplifier 26. The reference electrode amplifier 24 is configured to measure the equilibrium potential of the reference electrode for use by the control amplifier 26 in performing the voltage control described herein above.

[0040] The switch 22 is used (similarly to switch 12 described further below) to eliminate any current flowing through the sensor 10 during an idle period from activation (i.e. turning “ON”) of the sensor 10 to the start of actual data acquisition. As can be seen from Fig. 1 , the path from the reference electrode to the control amplifier 26 (via reference electrode amplifier 24) does not feature a switch, unlike the path to the counter electrode which comprises switch 22. This is due to the fact that the parasitic currents typically flowing through a switch negatively affect its operation. Because it is desirable for the currents from the reference electrode to remain as close to zero as possible, no switch is coupled to the reference electrode and a low input bias precision amplifier (such as a 3 fA amplifier) is preferably used as the reference electrode amplifier 24.

[0041] Still referring to Fig. 1 , in response to the control amplifier 26 providing the voltage waveform to the potentiostat 1 and adjusting the potential of the reference electrode, current flows from the control electrode to the working electrode and is recorded by the CPU 30. In particular, an analog electrical signal (indicative of the current measured at the working electrode) output via connection 11a is provided, via a switch 12, to a transimpedance amplifier 14 which is electrically connected in series with the switch 12 and serves as a current-voltage converter. The amplifier 14 is configured to amplify the signal from the working electrode and to provide the amplified signal to the CPU 30. In particular, the amplifier 14 amplifies the reaction current going through the working electrode to produce an output voltage of the potentiostat 1 . A resistor capacitor (RC) filter 18 is electrically connected in parallel with the transimpedance amplifier 14, and a resistance 17 is also electrically connected in parallel with the transimpedance amplifier 14. An analog switch 16 is provided to control the use of the resistance 17. The switch 16 is used to adjust the gain of the transimpedance amplifier 14, thereby allowing to cover the wider range of currents flowingthrough the working electrode and thus increasing the potentiostat’s dynamic range. Furthermore, a RC filter 19 is provided after the transimpedance amplifier 14 to ensure dynamic stability and for more effective signal filtering. It should be understood that, although not illustrated in Fig. 1 , a switch similar to switch 16 may be coupled to the control amplifier 26. The switches (e.g., switches 12, 22) provided in the potentiostat 1 are controlled by an IO expander 29 controlled by the CPU 30. The RC filter 18 (composed of a resistance connected in parallel with a capacitance) is used to filter the signal output by the working electrode and to reduce the intensity or amplitude of noise in the signal. The circuit may optionally comprise one or more additional RC filters to further filter out noise. The analog signal output by the transimpedance amplifier 14 is converted to a digital signal using an ADC 20 and provided to an input (not shown) the CPU 30 for processing. The ADC 20 is preferably a 24-bit Delta-Sigma ADC. It should however be understood that the ADC 20 may have any suitable bit depth other than 24.

[0042] It should be noted that the amplifier 14 has a predetermined sensitivity range. In a potentiostat with a plurality of sensitivity ranges, a plurality of amplifiers 14 can be employed in parallel each having a different sensitivity range. A switch 16 or plurality of switches 16 can be used to control which amplifier 14 receives the current from the working electrode.

[0043] In one embodiment, the potentiostat 1 also comprises a display (not shown) which is connected to the CPU 30 to display the results of the analysis performed based on measurements acquired using the potentiostat 1. The results may be displayed in any suitable manner. In one embodiment, if the same analyte is sensed in the multiple (e.g., six (6)) independent channels then a single result is displayed. It should however be understood that there may be multiple results identified for each of the multiple channels (for example six (6) different results) displayed if each channel analyzes a different analyte. In some embodiments, the display can be used as a user input interface, for example when implemented as a touch-screen. Alternatively or in addition, the potentiostat 1 can incorporate a mechanical keypad as a user input interface. Such an input interface may allow a user to provide inputs, such as related to the operation of the potentiostat 1 or the display of analysis results. As will be understood by those skilled in the art, the potentiostat 1 may also comprise a data storage component (e.g. SD card), a light sensor, an accelerometer, a Wi-Fi and / or Bluetooth connection, a Global Positioning System (GPS) component, a barcode reader, an encryption hardware, a temperature monitor, a heater, a power supply to recharge the batteries, a USB interface, and other suitable components.

[0044] The memory or data storage can include a suitable combination of any type of computer memory that is located either internally or externally such as, for example, randomaccess memory (RAM), read-only memory (ROM), compact disc read-only memory (CDROM), electro-optical memory, magnetooptical memory, erasable programmable read-only memory (EPROM), and electrically-erasable programmable read-only memory (EEPROM), Ferroelectric RAM (FRAM) or the like.

[0045] The CPU 30 provided in the potentiostat 1 can be operable to register and authenticate users (using a login, unique identifier, and password for example) prior to providing access to applications, a local network, network resources, other networks, and network security devices.

[0046] The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure.

[0047] Various aspects of the systems and methods described herein may be used alone, in combination, or in a variety of arrangements not specifically discussed in the embodiments described in the foregoing and is therefore not limited in its application to the details and arrangement of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments. Although particular embodiments have been shown and described, it will be apparent to those skilled in the art that changes, and modifications may be made without departing from this invention in its broader aspects. The scope of the following claims should not be limited by the embodiments set forth in the examples but should be given the broadest reasonable interpretation consistent with the description as a whole.

Claims

WHAT IS CLAIMED IS:

1. A potentiostat for sensing a presence of an analyte in a fluid sample, the potentiostat comprising: a sensor receiving region for receiving a sensor having the fluid sample provided thereon, the sensor comprising a plurality of independent sensing channels each having a working electrode and a reference electrode spaced from the working electrode, the working electrode and the reference electrode adapted to come in contact with the fluid sample; an analog circuit provided on a first island of a printed circuit board, the analog circuit comprising: a plurality of independent analog channels each comprising a counter electrode where each counter electrode forms a closed electrical circuit with the working electrode and the reference electrode to perform a voltametric scan on the fluid sample and obtain a plurality of voltametric signals for each of the plurality of independent analog channels; a first power supply to provide voltage to the counter electrode to perform the voltametric scan; and an analog to digital converter (ADC) configured for respectively converting the plurality of voltametric signals into a plurality of digital signals; and a digital circuit provided on a second island of the printed circuit board, the second island separate from the first island, the digital circuit connected to the ADC and receiving the plurality of digital signals, the digital circuit comprising a computing device configured to receive the digital signals form the ADC and to determine the presence of the analyte based on the digital signals as received and a digital to analog converter (DAC) connecting the computing device to the analog circuit for each of the plurality of independent sensing channels.

2. The potentiostat of claim 1 , wherein the fluid sample is a body fluid.

3. The potentiostat of claim 2, wherein the body fluid is saliva.

4. The potentiostat of any one of claims 1 to 3, wherein the analyte is selected from the group consisting of cannabinoids, benzodiazepines, opiates, semi-synthetic opioids, synthetic opioids, steroids, narcotics, alcohols, amphetamines, arbiturates, buprenorphine, methamphetamines, cotinine, phencyclidine (POP), 3,4-Methylenedioxy methamphetamine (MDMA), hallucinogens, ketamine, and gamma hydroxybutyrate.

5. The potentiostat of any one of claims 1 to 4, wherein the ADC is a 24-bit delta-sigma ADC.

6. The potentiostat of any one of claims 1 to 5, further comprising a resistor-capacitor filter in each of the plurality of independent analog channels.

7. The potentiostat of any one of claims 1 to 6, wherein the voltametric scans performed on each of the plurality of independent channels have different voltammetry profiles.

8. The potentiostat of any one of claims 1 to 7, wherein the potentiostat is contained in a handheld case having a width of less than 10 cm and a length of less than 30 cm.

9. The potentiostat of any one of claims 1 to 8, wherein the counter electrode comprises carbon ink or platinum.

10. The potentiostat of any one of claims 1 to 9, wherein the working electrode and the reference electrode comprise silver.

11. The potentiostat of any one of claims 1 to 10, wherein the analog circuit and the digital circuit are connected by a single ground connection.

12. The potentiostat of any one of claims 1 to 11 , wherein the voltametric scan is square wave voltammetry, cyclic voltammetry, linear sweep voltammetry, or differential pulse voltammetry.

13. The potentiostat of any one of claims 1 to 12, wherein the plurality of independent sensing channels are parallel.

14. A method of sensing the presence of one more analytes in a fluid sample, the method comprising: depositing the fluid sample on the sensor region of the potentiostat of any one of claims 1 to 13; andperforming a voltametric scan on each of the plurality independent sensing channels.

15. A method of sensing the presence of an analyte in a fluid sample, the method comprising: depositing the fluid sample on the sensor region of the potentiostat of claim 13; and performing a voltametric scan in parallel on each of the plurality independent sensing channels in parallel.

16. The method of claim 14 or 15, wherein the fluid sample is saliva.

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