VTT Technical Research Centre of Finland has developed a miniaturized optical sensor for gas detection in a cell phone. The sensor is based on a microelectromechanical (MEMS) Fabry-Perot interferometer, which is a structure with two highly reflective surfaces separated by a tunable air gap. The MEMS FPI is a monolithic device, i.e. it is made entirely on one substrate in a batch process, without assembling separate pieces together. The gap is adjusted by moving the upper mirror with electrostatic force, so there are no actual moving parts. VTT has designed and manufactured a MEMS FPI based carbon dioxide sensor demonstrator which is integrated to a cell phone shield cover. The demonstrator contains light source, gas cell, MEMS FPI, detector, control electronics and two coin cell batteries as a power source. It is connected to the cell phone by Bluetooth. By adjusting the wavelength range and customizing the MEMS FPI structure, it is possible to selectively sense multiple gases.
[1]
David S. Moore,et al.
Handbook of spectroscopy
,
2014
.
[2]
M. Sigrist.
Air monitoring by spectroscopic techniques
,
1994
.
[3]
R. Tatam,et al.
Optical gas sensing: a review
,
2012
.
[4]
Jussi Mäkynen,et al.
Hydrocarbon gas detection with microelectromechanical Fabry-Perot interferometer
,
2013,
Defense, Security, and Sensing.
[5]
A. Torkkeli,et al.
Electrically tuneable micromachined fabry-perot interferometer in gas analysis
,
1997
.
[6]
Antti Näsilä,et al.
MEMS Fabry-Perot interferometer-based spectrometer demonstrator for 7.5 μm to 9.5 μm wavelength range
,
2014,
Photonics West - Micro and Nano Fabricated Electromechanical and Optical Components.