Effects of temperature, humidity and pressure on the nano-based gas/breath analyzer performance on the gate-voltage enabled detection of acetone and ethanol

Abstract

Breath analysers for alcohol and other breath biomarker are affected by a number of environmental parameters. Of these, humidity, temperature and pressure are the most important. This paper explores the performance of four nanomaterials- VO2, WO3, SnO2 and Co-ZnO- in four prototype breath analysers on the detection of acetone and ethanol with the sensing materials harnessed around the patented LAteral Gate with Inter-Digitated Drain-Source Field Effect Transistor (LAGIDDSFET). In particular, in terms of operating temperature and the ability to show visible peaks in the LAGIDDSFET's drain-current-gate-voltage characteristics in acetone, it is found that the VO2-based breath analyser outperforms the rest of the materials. Since acetone and air (mainly oxygen) are reducing and oxidising atmospheres respectively, an interesting competition between these two atmospheres at a gate voltage of −10 V are observed with consequential deletion of the −10 V peak when acetone concentrations increase. Sensor operating temperature and the ambient temperature in the chamber are found to shift the critical gate voltages to lower absolute values, humidity shifts the critical gate voltages to higher voltages whereas pressure has very little effect in these shifts.