Friday, December 09, 2005

Nanotechnology—Make Sensors Smaller and Cheaper

Nanotechnology pushes the boundary not only on the electromechanical side of the device but also on the sensing side. Chemical sensors using organic semiconductors and inkjet printing technology are now a reality. University of California, Berkeley’s Subramanian claims to make these sensors for $0.30 each. Borrowing the concept from how the human nose detects smells, Subramanian uses an array of sensors to detect a variety of chemicals.
Using inkjet printing technology appears to be a common theme. Here’s a paper from 2003 describing the technique.

Sensors array have been used in an Electronic Nose application in which sensor arrays detect volatile chemical elements (those that tantalize the human senses). A sensor array – each one tuned to a slightly different element more closely approximates how one may taste or smell. Chromatography and Mass Spec techniques try to resolve each element but this is insufficient since it doesn’t take into account the interaction with the human senses. The sensor array can change its reading based on the chemical interactions it receives. Also, a series of sensors can provide a more accurate portrait of a target chemical especially when coupled with pattern matching software. Applications range from food, beverage testing to gas vapor analysis, to medical.

NASA Tech Briefs describe an optical sensor array modeled on a moth’s eye (which reflects no light) that uses nanometer size pillars shorter than the wavelength of light. By varying the size of the pillars one can build a filter/sensor spectrometer unit with no moving parts.

Researchers at the University of Tokyo use arrays of organic sensors to create a “skin-like” material that can sense pressure. One application is to spread this material on the floor so if someone falls, the sensors in the skin can detect the presence and the condition of the subject. It can also be applied to robotics applications in non-trivial applications such as a robot picking up an egg. The sensors can detect the amount of the pressure being applied and the objects’ response to it.

Startups are also working in this space.
Concentris a Swiss-based company uses cantilever arrays to detect chemicals in their instruments.

If you are working with sensor arrays, I would like to hear from you. You can reach me at hall.martin@ni.com.

Best regards,
Hall T. Martin