Sensor system and methods of making
Sensors having an advantageous design and methods for fabricating such sensors are generally provided. Some sensors described herein comprise pairs of electrodes having radial symmetry, pairs of nested electrodes, and/or nanowires. Some embodiments relate to fabricating electrodes by methods in which nanowires are deposited from a fluid contacted with a substrate in a manner such that it evaporates and is replenished.
1. A method of depositing a plurality of nanowires onto a substrate, comprising:
expelling a fluid comprising the plurality of nanowires from a nozzle onto the substrate;
allowing at least a portion of the fluid to evaporate;
replenishing at least a portion of the evaporated fluid by expelling a further amount of the fluid from the nozzle; and
holding the fluid comprising the plurality of nanowires in contact with the substrate for a time period of greater than or equal to 0.2 sec,
wherein the fluid is in contact with both the substrate and the nozzle during the holding, replenishing and evaporation steps.
2. A method as in claim 1 , wherein the method comprises forming a sensor comprising greater than or equal to 10 and fewer than or equal to 40 pairs of electrodes.
3. A method as in claim 1 , wherein the plurality nanowires has a length of greater than or equal to 5 microns and less than or equal to 50 microns.
4. A method as in claim 1 , wherein the plurality of nanowires comprises single-crystalline silicon.
5. A method as in claim 1 , wherein the plurality of nanowires comprises nanowires having charged surfaces and/or comprises a binding entity.
6. A method as in claim 1 , wherein the plurality of nanowires comprises a binding entity for a biomarker for brain injury.
7. A method as in claim 1 , wherein the plurality of nanowires comprises a binding entity for small-molecule biomarker, lipids, and/or a viral protein.
8. A method as in claim 7 , wherein the viral protein is a human viral protein, a non-human animal viral protein, and/or a plant viral protein.
9. A method as in claim 7 , wherein the viral protein is a SARS-CoV-2 protein, an influenza virus protein, a zika virus protein, a parainfluenza virus protein, a HIV1 virus protein, and/or a HHV virus protein.
10. A method as in claim 1 , wherein the method comprises forming a sensor comprising a blocking layer.
11. A method as in claim 10 , wherein the blocking layer is disposed on the plurality of nanowires.
12. A method as in claim 10 , wherein the blocking layer comprises a protein.
13. A method as in claim 10 , wherein the blocking layer comprises a stabilizer which is removed upon contact with liquid.
14. A method as in claim 1 , wherein the method comprises forming a sensor, further comprising exposing the sensor as to a fluid.
15. A method as in claim 14 , wherein the fluid comprises a bodily fluid.
16. A method as in claim 15 , wherein the bodily fluid is blood, is plasma, is saliva, is tears, is urine, is a nasal fluid, is a nasopharyngeal fluid, was obtained through finger stick, was collected using a swab, and/or comprises a solid or viscous sample resuspended in another fluid.
17. A method as in claim 1 , wherein the method comprises forming a sensor, and wherein the sensor is configured to output a signal indicative of a concentration of the protein in the fluid.
18. A method as in claim 1 , wherein the evaporation step and the replenishing step are performed simultaneously, and/or wherein the evaporation step and the holding step are performed simultaneously.
19. A method as in claim 1 , wherein the substrate is heated during the evaporation step.
20. A method as in claim 1 , wherein the fluid comprises an organic solvent with boiling point less than 120° C.
21. A method as in claim 1 , further comprising depositing a photoresist on the nanowires.
22. A method as in claim 1 , further comprising depositing a metal on the nanowires to form an electrode.
23. A method as in claim 22 , further comprising heating the electrode and the nanowires, and wherein heating the electrode and the nanowires causes the formation of an ohmic contact therebetween.
24. A method as in claim 22 , further comprising depositing a photoresist on the electrode.
25. A method as in claim 24 , wherein the photoresist comprises an SU8, comprises a polyimide, and/or is a poly-imide based photoresist.
26. A method as in claim 22 , further comprising depositing a second metal on the metal to form an electrode configured to be in electrical communication with an environment external to the sensor.
27. A fluidic device comprising a plurality of sensors formed by the method of claim 1 .
28. A method as in claim 1 , wherein the method comprises forming a sensor, and wherein the sensor comprises a plurality of pairs of electrodes that are equidistant from a center point.
29. A method as in claim 1 , wherein the method comprises forming a sensor, and wherein the sensor comprises two or more groups of nanowires that are functionalized with different chemistries.