CSIR-Central Glass & Ceramic Research Institute
(A Unit of Council of Scientific and Industrial Research)

सीएसआईआर-केंद्रीय कांच और सिरेमिक अनुसंधान संस्थान
(वैज्ञानिक और औद्योगिक अनुसंधान परिषद की एक इकाई)
  
  
 


  Activity II (BESU, CSIR-CGCRI)
  • MEMS microheaters are designed and fabricated for entire two inch (2") process and 3mmX3mm die sized microheaters obtained.

  • Low power electronic circuit for methane sensing has been developed and packaged in a pocket size unit.

Explosions are a phenomenon of underground coal mining and they may be either due to Methane (firedamp) alone or coal dust alone or both fire damp and coal dust. An early detection and alarm system for the presence of methane and CO gas in the underground coal mining environment will thus go a long way for ensuring the safety and security of the coal mines. Low power consumption is a fundamental requirement for a sensor system with an acceptable battery lifetime. Conventional metal oxide gas sensors, which are commonly used for sensing inflammable gases ((like CH4) and other toxic gases (like CO)) suffer from relatively high temperature (>=300oC) leading to high power consumption (e.g. pellistors require 350-850mW and Taguchi gas sensors require 230-760mW). However, the application of silicon MEMS technology may permit the desired benefits of reduced thermal mass, miniaturization, low power, reproducibility and low unit-cost.

 
  Deliverables/Outcome of the project are:
  • To develop packaged MEMS-based microheaters and sensors / sensor arrays for detection of methane/carbon monoxide.

  • b) To develop necessary signal processing unit (hardware and software) and its suitable packaging for interfacing with the sensors .



 
  Objective:
  • To design and fabricate low temperature, low power MEMS based microheater platform for integration with metal oxide (ZnO) sensing layer.

  • To design a microcontroller based signal conditioning circuit which will interface with MEMS based gas sensor and micro-heater to control their operation in an intelligent and energy efficient manner.



 
  Development Methodology:
Specifications of the device:
Specifications of the microheater:
  • Power consumption             : <=100mW

  • Operating voltage             : 5V

  • Microheater filament             : Titanium, Platinum

  • Operating temperature             : =200oC

  • Sensor Electrode:             : Coplanar IDE


Specifications of the Sensing layer:
  • Sol-gel/ Sputtering deposition of ZnO

  • Reduction of operating temperature down-to 200oC.

  • Nano structures responsible for this low temperature response.


Specification of electronic circuit:
  • Battery operated portable circuit.

  • Micro heater: heating current 60mA.

  • Gas sensor resistance variation 10k&񗡖 to 10M&񗡖.

  • Pulsed mode operation.

  • LCD display on demand.

  • Value store on demand.

  • Battery checking facility.

  • LED blink (Indication) on different gas concentration.

  • Buzzer (Alarm) for high gas concentration.



 
 
Process flow chart of entire 2" process for obtaining 3mmX3mm die of microheater platform


 
  Results Obtained:

Packaged Microheater with IDE


Microphotograph of Ti/Pt Microheater and IDE


Gas sensor signal conditioning unit


Final Packaged System



 
  Achievements in the last one-year:
  • MEMS microheaters and ZnO thin film methane gas sensors are designed and fabricated for an entire 2" (two inch Silicon wafer process) having a 3mmX3mm die size.
  • Low power electronic circuit for methane sensing has been developed and packaged in a pocket size unit.


 
  Research Publications and Patents
  1. S. Ghosh, S. Maity, A. Kundu, S. Chatterjee, H. Saha, Thermal analysis of cantilever MEMS based low power microheater array for the selective detection of explosive and toxic gases, ISPTS1, Pune University, 2012.
  2. Sunipa Roy, Tanusree Majhi, Avra Kundu, C. K. Sarkar and H.Saha Design, Fabrication and simulation of coplanar microheater using Nickel alloy for low temperature gas sensor applications, Sensor Letters, Vol. 9, 1-8, 2011.
  3. A Kundu, N C Mondal, S Basu, H Saha, Alternative high- k dielectric TiO2 films for RF MEMS capacitive shunt switches, National Seminar on Recent Advances in Material Sciences (RAMS) February 15-17, p 51 (2008).


 




    Updated on: 05-04-2016 15:11 
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