Fabrication and Performance of Solution-Based Micropatterned DNA Functionalized Carbon Nanotube Network as Humidity Sensors

The paper describes a new technique of precise drop dispensing of deoxyribonucleic acid functionalized single walled carbon nanotube (DFC) solution by microfluidic cantilevers for use as resistance-type humidity sensors. Electrodes of different gap lengths L = 10, 15, 20, and 25 μm were accurately bridged by DFC drops of desired diameter by regulating the relative humidity (RH) of the chamber, contact time tc of the microcantilever type surface patterning tool touching the substrate and the UV/ozone exposure time tUV of the substrate. Sensor performance, including sensitivity and dynamic response characteristics, is investigated in detail for L = 25 μm in the RH range of 20%-90%. The phenomenon of electric field assisted desorption of water molecules from the sensor surface is explained from the decrease in recovery time with the bias voltage. The device shows excellent dynamic repeatability and fairly good environmental stability over a period of one month.