Deoxyribonucleic Acid Functionalized Carbon Nanotube Network as Humidity Sensors

Abstract

In this paper, deoxyribonucleic acid functionalized carbon nanotube (DFC) network has been used to develop field effect transistor (FET)-based humidity sensor. The sensor works on the principle of variation of conductance of the DFC network with change in relative humidity. Since the output signal current of the sensor increases exponentially with increase in RH, the device offers higher sensitivity especially at higher RH. The response and recovery times of this zero gate biased FET-based humidity sensor are measured to be 4 and 8 s, respectively, and offers no baseline shift during recovery, which indicates that the sensing mechanism is governed by charge transfer between the DFC and water molecules. The device is highly selective to atmospheric humidity, having no response to nitrogen and oxygen. The effect of temperature on the performance of the sensor is also studied and reported in this paper.

Humidity Sensor Based on High Proton Conductivity of Graphene Oxide

“…However, resistive humidity sensor gains advantage over all the aforementioned humidity sensors owing to its cost-effective fabrication, easy to integrate with CMOS (Complementary Metal Oxide Semiconductor) platform and easy and efficient operation. There have been several reports of resistive humidity sensors based on metal oxide nano particles [7], polymers [8] and carbon nanotubes [9]. Polymer humidity sensors suffer from long term stability [10].…”

Electric-Field Assisted Desorption of Water Molecules in DNA Functionalized CNT Network

“…It was shown in our previous work [11] that functionalization of CNT by ssDNA provides hydrophilic sites on the nanotube surface which increases the sensitivity of detection. But since humidity sensing is governed by the phenomenon of adsorption and desorption, the devices often suffer from delayed response and recovery times.…”

“…Ionic charges are developed on the DFC network not only due to transfer of electrons on exposure to water molecules [11] but also as a result of bond breaking of the phosphate group and self dissociation of water molecules forming H 3 O + and OH − ions [16], [17]. The reduction in ion binding energy ( ion = l c E ) is inversely proportional to the applied dc electric field E where l c is a constant for a system for a fixed temperature called the confinement length.…”

Immobilization of Bovine Serum Albumin Upon Multiwall Carbon Nanotube for High Speed Humidity Sensing Application

“…So, noncovalent attachment of biomolecule is more suitable approach than covalent counterpart. As a consequence, immobilization of biomolecules like DNA [7] or protein is a potential strategy to make an innovative nano-bio hybrid material based humidity sensing technique. Our proposed technique is one of the simplest method so far to attain a high speed humidity sensor using solution processed IBC.…”

“…Calibration curve was established measuring the exponential variation of output signal current as a function of humidity ranging from 35% to 80% with different bias for 0.5V, 1V, 1.5V and 2V respectively. Exponential fitting were performed according to the following equation [7] = × − 0 (2) Where A, B and I0 constant can be obtained at a particular bias voltages. (3) For each calibration curve at a particular bias voltage using the coefficients A, B and I0 the LOD can be obtained from the equation (3).…”