Thermoelectric infrared sensors

There are endless applications for infrared sensors and arrays (cameras), examples such as obstacle detection, night vision, circuit debugging, preventative maintenance, industrial diagnosis, and medical surgery are just a few of the current uses.

In the past, IR cameras have been quite expensive and bulky, but new microfabrication technology and advancement in the materials is constantly reducing the cost which is why in just the past few years passive IR sensors have become available to the average consumer and light industry.

There are two main types of infrared sensors: photon and thermal. In our lab, we study thermal specifically, which involves radiant heating of a part of the sensor as a means of detecting IR light.  Since mid range IR (thermal IR) light can radiantly heat objects easily, uncooled sensors are often designed to have an IR absorber and sensor element that is thermally isolated from its surroundings and support in an effort to provide maximum temperature change upon absorbing IR light.  This heat change or difference is then transduced to electricity in one of three ways; by changing of resistance in a conductor as in a thermistor, by direct energy conversion as in a thermocouple, or by spontaneous polarization phenomenon (pyroelectric effect) which happens when a pyroelectric material experiences a change in temperature.  

In our lab we are trying to come up with new materials and fabrication processes to enhance the performance of passive IR sensors while at the same time trying to reduce the manufacturing cost in an effort to keep the sensor design practical.