Device for measurement of exhaled nitric oxide concentration
Described is a personal device and methods for measuring the concentration of an analyte in a sample of gas. The device and method may utilize a chemically selective sensor element with low power consumption integrated with circuitry that enables wireless communication between the sensor and any suitable electronic readout such as a smartphone, tablet, or computer. In preferred form, the sensor circuitry relies upon the quantum capacitance effect of graphene as a transduction mechanism. Also in preferred form, the device and method employ the functionalization of the graphene-based sensor to determine the concentration of nitric oxide in exhaled breath.
1. A device for detecting an analyte in a sample, comprising:
one or more analyte sensors, at least one analyte sensor having a graphene-based variable capacitor,
wherein at least one graphene-based variable capacitor comprises:
a dielectric layer;
a graphene layer which is substantially supported by the dielectric layer; and
a modifying layer in contact with the graphene layer; and
a sensor signal processor, programmed to receive data from the at least one analyte sensor having a graphene-based variable capacitor and to determine the concentration of nitric oxide in the sample.
2. The device of claim 1 , wherein the modifying layer is non-covalently bound to the graphene layer.
3. The device of claim 1 , wherein the modifying layer comprises molecules having a porphyrin ring system.
4. The device of claim 1 , wherein the modifying layer comprises molecules of formula (I):
wherein
n is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10;
each R is independently H, —C 1 -C 10 alkyl, C 1 -C 10 alkenyl or phenyl;
each R 1 is independently —H, —OH, —NR 2 , C 1 -C 10 alkyl, -G, —O-G, —N(R)-G, —C 1 -C 10 alkyl-G, wherein G is the graphene layer;
M is a metal; and
X is halogen or cyano.
5. The device of claim 4 , wherein the modifying layer comprises molecules of formula (Ia):
wherein
each R 1 is independently —H, —OH, —NR 2 , C 1 -C 10 alkyl, -G, —O-G, —N(R)-G, —C 1 -C 10 alkyl-G, wherein G is the graphene layer;
M is a transition metal; and
X is halogen or cyano.
6. The device of claim 5 , wherein the modifying layer comprises molecules of formula (Ib):
wherein
M is a transition metal; and
X is halogen or cyano.
7. The device of claim 6 , wherein
M is Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Pb or Zn; and
X is chloro, bromo, iodo or cyano.
8. The device of claim 7 , wherein the modifying layer comprises molecules of the structure:
9. The device of claim 1 , wherein the graphene-based variable capacitor further comprises a gate electrode and a top electrode.
10. The device of claim 9 , wherein the gate electrode and the top electrode are arranged in a multi-finger, planarized geometry.
11. The device of claim 9 , wherein the gate electrode is embedded in a supporting substrate.
12. The device of claim 9 , wherein the gate electrode is in contact with the dielectric layer, wherein the dielectric layer comprises a material having a high dielectric constant.
13. The device of claim 12 , wherein the modifying layer comprises hemin chloride non-covalently bound to the graphene layer.
14. The device of claim 13 , further comprising a power supply.
15. The device of claim 9 , wherein the modifying layer comprises hemin chloride non-covalently bound to the graphene layer.
16. The device of claim 1 , further comprising a permeable polymer membrane in contact with the modifying layer.
17. The device of claim 1 , wherein the modifying layer comprises hemin chloride non-covalently bound to the graphene layer.
18. The device of claim 1 , further comprising a power supply.
19. The device of claim 1 , wherein the sensor signal processor processes data directly from the at least one analyte sensor having a graphene-based variable capacitor.
20. The device of claim 1 , wherein the sensor signal processor processes raw data from the at least one analyte sensor having a graphene-based variable capacitor.
21. The device of claim 1 , wherein the data from the at least one analyte sensor having a graphene-based variable capacitor is an analog signal from the graphene-based variable capacitor.
22. The device of claim 1 , wherein the graphene layer is in direct contact with the dielectric layer.
23. The device of claim 22 , wherein the direct contact with the dielectric layer is at least partially continuous.
24. The device of claim 1 , wherein the analyte is gaseous nitric oxide.