MEMS-Based Micro Sensor Detecting the Nitrogen Oxide Gases

Jung Sik Kim, Jin Ho Yoon, Bum Joon Kim

Research output: Contribution to journalArticlepeer-review


In this study, a micro gas sensor for NOx was fabricated using a microelectromechanical system (MEMS) technology and sol-gel process. The membrane and micro heater of the sensor platform were fabricated by a standard MEMS and CMOS technology with minor changes. The sensing electrode and micro heater were designed to have a co-planar structure with a Pt thin film layer. The size of the gas sensor device was about 2 mm × 2 mm. Indium oxide as a sensing material for the NOx gas was synthesized by a sol-gel process. The particle size of synthesized In2O3 was identified as about 50 nm by field emission scanning electron microscopy (FE-SEM). The maximum gas sensitivity of indium oxide, as measured in terms of the relative resistance (Rs=Rgas/Rair), occurred at 300oC with a value of 8.0 at 1 ppm NO2 gas. The response and recovery times were within 60 seconds and 2 min, respectively. The sensing properties of the NO2 gas showed good linear behavior with an increase of gas concentration. This study confirms that a MEMS-based gas sensor is a potential candidate as an automobile gas sensor with many advantages: small dimension, high sensitivity, short response time and low power consumption.

Original languageEnglish
Pages (from-to)299-303
Number of pages5
JournalKorean Journal of Materials Research
Issue number6
StatePublished - 2013


  • Gas sensor
  • Indium oxide
  • Mems
  • Nitrogen oxides
  • Sol-gel process


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