Ammonia Chemical Microsensor Using ZnO Thin Film and Novel Microheater Design

Volume 2 - Issue 4

Kolev G¹, Denishev K¹, Aleksandrova M¹* and Tzaneva B²

Received: February 14, 2020;   Published: February 25, 2020

DOI: 10.32474/MAMS.2020.02.000142

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Abstract

Microsensor design for ammonia (NH₃) gas detection was proposed. The sensor is 4 segmented and consists of sensing resistors - interdigitated electrodes and ammonia sensing layer, deposited on thermal oxidized silicon substrate with specific in shape microheater and thermocouple. The zinc oxide (ZnO) layer, grown by RF sputtering method, was used as an ammonia sensing coating. The ammonia sensor, which is of resistive type, changes its resistance, when the sensing film adsorbs or desorbs ammonia gas. The thermal decomposition of ammonium bicarbonate (NH₄HCO₃) is used to provide constant and stable ratio NH₃: CO₂ = 2:1, receptivity 66% and 33% [g/mol] in volume. The results obtained from the testing of the ammonia gas are reported for temperature range between 25°C and 50°C. Resulting change in the segments resistance is in the range between 134MΩ to 56MΩ with excellent linearity and short response time.

Keywords: Gas microsensor design, ZnO film, RF sputtering, Chemiresistive sensors, Surface micromachining

Abstract| Introduction| Materials and Methods| Results and Discussion| Conclusion| Acknowledgment| References|