Corrosion Enhanced Capacitive Strain Gauge at 370°C

Abstract

In this paper a silicon carbide passivated capacitive strain sensor is proposed which continuously and accurately measures strain in corrosive ambient and operates up to 370ºC in air. The analytical model of this low-mechanical noise, highresolution and high-gain capacitive SiC coated sensor predicts 45 aF/µε sensitivity, which is in a good agreement with finite element analysis (within 12%) over the intended full-scale range of 1-1000 µε. The gauge is fabricated using silicon-oninsulator and coated with a thin (~ 60nm) pinhole-free 3C-SiC layer. The integrity of the passivation layer is tested using a hot KOH bath followed by SEM inspection which shows no defects or damage. A localized-heating, high-temperature testing setup has been built using an infra-red lamp to heat the gauge up to 370ºC while maintaining the electronics at significantly reduced temperatures. Experimental results show the strain gauge successfully continues to operate at 370ºC.

Thermal Flow Sensors for Harsh Environments

“…These conditions are typically found in combustion optimization and emission control, oil industries, chemical process control, the propulsion systems of spacecraft and deep-sea devices [ 2 , 3 ]. In recent years, a number of flow sensors have been fabricated and characterized for the measurement of pressure [ 4 , 5 , 6 ], temperature [ 7 , 8 ], gas species [ 9 , 10 , 11 , 12 , 13 ], strain [ 14 , 15 , 16 , 17 ] and acceleration [ 18 , 19 ] in these environments. In addition, there has been growing demand for developing high-temperature miniaturized flow sensors with fast response times and low cost through mass fabrication.…”

Thermal Flow Sensors for Harsh Environments

“…Figure 1(a) represents various MEMS sensors and the associated harsh environment conditions .These conditions are common to applications such as combustion optimization and emission control, oil industries, chemical process control and propulsion system of a spacecraft. In recent years, a range of prototype sensors have been fabricated and tested for the measurement of pressure [2][3][4], temperature [5,6], gas species [7][8][9][10][11], strain [12][13][14][15] and acceleration [16,17] in these environments. In addition to the parameters described, there has been growing demand for developing a flow sensor that has high temperature capability yet is small in size, fast in response time and low cost through mass fabrication.…”