High sensitivity ion selective sensors implemented through feedback circuitry
The following relates generally to ion sensing using organic electrochemical transistors (OECTs). In one aspect, a device comprises: an amplification portion including an OECT; a feedback portion that receives a differential voltage from the amplification portion and outputs a feedback signal; and a readout portion which receives the feedback signal and outputs an output voltage.
1. A device for measuring ion concentration in an analyte solution, comprising:
an amplification portion comprising a first inverter and a second inverter, the first inverter comprising an ion sensing organic electrochemical transistor (OECT);
a feedback portion configured to:
receive a voltage input from the OECT; and
provide a feedback signal to the first inverter and a readout portion.
2. The device of claim 1 , wherein:
the first inverter further comprises a non-sensing OECT comprising an encapsulant; and
the second inverter comprises two non-sensing OECTs including encapsulants.
3. The device of claim 1 , wherein the feedback portion comprises a comparator, a resistor, and a capacitor.
4. The device of claim 3 , wherein the comparator is configured to:
receive the voltage input from the OECT at a positive input terminal of the comparator; and
output a feedback voltage to the capacitor and the resistor.
5. The device of claim 4 , wherein:
the capacitor is connected to a negative input terminal of the comparator; and
the resistor is connected to the first inverter and the readout portion.
6. The device of claim 5 , wherein:
the resistor has a resistance of approximately 10 MΩ; and
the capacitor has a capacitance of approximately 100 nF.
7. The device of claim 4 , wherein the negative input terminal of the comparator is further connected to the second inverter.
8. The device of claim 1 , wherein the readout portion is configured to:
receive the feedback signal at a positive input terminal of a comparator; and
output an output voltage to a negative input terminal of the comparator.
9. A device for measuring ion concentration in an analyte solution, comprising:
an amplification portion comprising a first inverter and a second inverter, the first inverter comprising an ion sensing organic electrochemical transistor (OECT);
a feedback portion configured to:
receive a differential voltage signal from the amplification portion; and
provide a feedback signal to the first inverter and a readout portion.
10. The device of claim 9 , wherein:
the first inverter further comprises a non-sensing OECT comprising an encapsulant; and
the second inverter comprises two non-sensing OECTs including encapsulants.
11. The device of claim 9 , wherein the feedback portion comprises a comparator, a resistor, and a capacitor.
12. The device of claim 11 , wherein the comparator is configured to:
receive the differential voltage from the amplification portion; and
output a feedback voltage to the capacitor and the resistor.
13. The device of claim 12 , wherein:
the capacitor is connected to a negative input terminal of the comparator; and
the resistor is connected to the first inverter and the readout portion.
14. The device of claim 13 , wherein the negative input terminal of the comparator is further connected to the second inverter.
15. The device of claim 9 , wherein:
the first inverter further comprises a non-sensing OECT comprising an encapsulant encapsulating a reference solution; and
the second inverter comprises two non-sensing OECTs including encapsulants encapsulating the reference solution.
16. A method of measuring ion concentration in an analyte solution, comprising:
with an amplification portion comprising an ion sensing organic electrochemical transistor (OECT), outputting a differential voltage to a feedback portion; and
with the feedback portion, providing a feedback signal to the amplification portion and a readout portion.