Measurement systems and associated techniques for sensing electrical characteristics of a sensor
Systems, devices, and methods of sensing electrical characteristics of a sensor are generally provided. Measurement devices described herein employ techniques for improved sensitivity when sensing electrical characteristics of a sensor. In some aspects, measurement devices described herein may be configured to reduce the impact of current noise generated in components of a measurement system when sensing electrical characteristics of the sensor. The techniques described herein may facilitate the inclusion of larger sense resistors in measurement devices, which increases the sensitivity of the system. In some aspects, such techniques may also facilitate coupling the sensor between the measurement device and ground when sensing the electrical characteristics for improved protection against overvoltage events such as electrostatic discharge (ESD).
1. A system comprising:
a sensor configured to generate an impedance greater than 0.5 megaohms (M Ω) when at least some analytes are disposed proximate the sensor; and
circuitry configured to provide an alternating current (AC) voltage to the sensor and sense electrical characteristics of the sensor in response to the AC voltage, the circuitry comprising:
a sense resistor coupled to the sensor;
a first amplifier having a first input, a second input, and an output, with the sense resistor coupled between the second input and the output; and
a second amplifier comprising:
a first input coupled to the output of the first amplifier;
a second input coupled to the first input of the first amplifier; and
an output configured to provide a voltage indicative of the electrical characteristics of the sensor,
wherein the first amplifier is configured to provide the AC voltage to the sensor via the second input.
2. The system of claim 1 , wherein the electrical characteristics include a conductance of the sensor.
3. The system of claim 2 , wherein the sensor is a nanowire sensor, and wherein the nanowire sensor is configured such that the conductance indicates a presence of one or more analytes at a surface of the nanowire sensor.
4. The system of claim 3 , wherein the surface of the nanowire sensor comprises a binding entity for a biomarker for brain injury.
5. The system of claim 3 , wherein the surface of the nanowire sensor comprises a binding entity for a biomarker for one or more infectious disease agents.
6. The system of claim 1 , further comprising a transimpedance amplifier (TIA) including the sense resistor and the first amplifier, wherein the TIA is configured to generate a sense voltage indicative of a current flowing through the sensor.
7. The system of claim 6 , further comprising an integrated circuit package, wherein the TIA is contained in the integrated circuit package, the TIA comprises a plurality of discrete components, and the plurality of discrete components comprises a field-effect transistor (FET).
8. A system, comprising:
a sensor configured to generate an impedance greater than 0.5 megaohms (M Ω) when at least some analytes are disposed proximate the sensor; and
circuitry configured to provide an alternating current (AC) voltage to the sensor and sense electrical characteristics of the sensor in response to the AC voltage, the circuitry comprising:
a sense amplifier comprising a first input and an output, the sense amplifier configured to generate a voltage indicative of the electrical characteristics at the output; and
a transimpedance amplifier (TIA) comprising an amplifier, the amplifier comprising:
a first input coupled to the first input of the sense amplifier; and
a second input coupled to, and configured to provide the AC voltage to, the sensor.
9. The system of claim 8 , wherein the electrical characteristics include a conductance of the sensor.
10. The system of claim 9 , wherein the sensor comprises a nanowire sensor, and wherein the nanowire sensor is configured such that the conductance indicates a presence of one or more analytes at a surface of the nanowire sensor.
11. The system of claim 10 , wherein the surface of the nanowire sensor comprises a binding entity for a biomarker.
12. The system of claim 11 , wherein the biomarker is a biomarker for brain injury.
13. The system of claim 11 , wherein the biomarker is a biomarker for one or more infectious disease agents.
14. The system of claim 8 , wherein:
the amplifier of the TIA further comprises an output electrically coupled to a second input of the sense amplifier;
the amplifier of the TIA is configured to generate a sense voltage at the output of the amplifier of the TIA that is indicative of a current through the sensor; and
the TIA further comprises a sense resistor electrically coupled between the first input of the amplifier of the TIA and the output of the amplifier of the TIA and configured to generate the sense voltage when the current flows through the sense resistor.
15. The system of claim 14 , wherein the amplifier of the TIA is further configured to receive an input voltage signal at the first input of the amplifier of the TIA and to apply the input voltage signal to the sensor via the second input of the amplifier of the TIA.
16. A system for sensing electrical characteristics of a sensor, comprising:
a sensor comprising a first electrode and a second electrode, the sensor configured to generate an impedance between the first electrode and the second electrode that is greater than 0.5 M Ω when at least some analytes are disposed proximate the sensor;
a transimpedance amplifier (TIA) comprising an amplifier configured to provide an alternating current (AC) voltage across the first electrode and the second electrode of the sensor; and
a sense amplifier configured to generate a voltage indicative of the electrical characteristics of the sensor responsive to detecting a current flowing between the sensor and ground, the electrical characteristics of the sensor comprising the impedance between the first electrode and the second electrode, and the impedance being indicated by a relationship between the AC voltage and the current flowing between the sensor and ground,
wherein the current flowing between the sensor and ground is responsive to the sensor receiving the AC voltage from the amplifier of the TIA while at least some analytes are disposed proximate the sensor.
17. The system of claim 16 , wherein the amplifier of the TIA is configured to receive the AC voltage from an AC voltage source having a frequency between 500 Hz and 700 Hz.
18. The system of claim 16 , wherein the electrical characteristics include a conductance of the sensor.
19. The system of claim 18 , wherein the sensor comprises a nanowire sensor, and wherein the nanowire sensor is configured such that the conductance indicates a presence of one or more analytes at a surface of the nanowire sensor.
20. The system of claim 19 , wherein the nanowire sensor is configured to generate an impedance greater than 0.5 M Ω when at least some analytes are disposed at the surface of the nanowire sensor.
21. The system of claim 19 , wherein the surface of the nanowire sensor comprises a binding entity for a biomarker for brain injury.
22. The system of claim 19 , wherein the surface of the nanowire sensor comprises a binding entity for a biomarker for one or more infectious disease agents.
23. The system of claim 16 , wherein an input of the amplifier of the TIA is configured to receive the current and an output of the amplifier of the TIA is configured to provide a sense voltage to the sense amplifier, and wherein the TIA further comprises a sense resistor configured to generate the sense voltage when the current flows through the sense resistor.