Development of Small Pressure Sensing Unit using Nano-Materials

Abstract

Precise measurement of low and high pressures for various types of applications has always been a challenge. Various types of nano-materials exhibit the property of change in electrical resistance upon the application of pressure. In this paper, we develop a handy pressure sensing unit for measuring minor changes in pressures by measuring changes in electrical resistance of the compressed nano-materials. The unit consists of a cylindrical arrangement upon which load is applied. This cylinder is connected with a Data Acquisition System (DAQ) to obtain the variations in voltage. We used multi walled carbon nanotubes (MWCNTs) as the transducer. Considering that the inner structure of these nanotubes is hollow, the vacant spaces allow larger flow of current through them. The experiment has been conducted using a small setup in which nearly 5 mg of MWCNTs were used and static pressure was varied from 150 gm to 5.13 kg in steps. The experiment was conducted for both loading and unloading cycles. It has been observed that when the external pressure increased from 0 to 1.2MPa, the electrical resistance fell by nearly 65% from 5.434 Ohm to 1.889 Ohm. The results obtained during present study are very useful in estimating the unknown external static loads by calibrating them with change in electrical resistance or voltage drop across the setup.