It is good to see an environmental sensor company go public (Tiger Optics); however, I must concede that I expect a lag of a year or two in the sensor IPO activity I predicted in my Clean Technology Trends for 2006 blog.

Of particular interest is the number of companies likely to commercialize sensors based on nanotechnology in the 2007/8 timeframe. A clear R&D target is sensors for hydrogen detection, a function in high demand as we use more hydrogen to power our economy. Here are some promising hydrogen nano-sensor technologies receiving attention this month.

Palladium Plays

Applied Nanotech’s metal nanoparticle sensor (MNPS) — films of metal nanoparticle alloys — detects hydrogen gas, CO and other gases, as well as chemicals.  MNPS technology has not been widely used in sensors. By using palladium particles to dissociate and dissolve hydrogen as small as parts per million, ANI’s technology is demonstrating response times of two seconds. Applied Nanotech is part of the intellectual property portfolio of Nano-Proprietary, Inc. (OTC Bulletin Board: NNPP), and is certain to be spun off at some point.

This palladium hydrogen nano-sensor has been perking up the fuel cell world this week. Yokohama National University is using palladium dust in an ultra-sensitive sensor that detects hydrogen gas in under one second, and in amounts as small as 100 parts per million.


A NASA-funded project at the




has developed a hydrogen sensor that claims to have solved the hydrogen storage paradox, although its technology is a mystery of its own.  It apparently “draws its power from a tiny internal source that harvests energy from small vibrations.”  A Space Daily article goes on to say the sensor can operate continuously without batteries off the slight vibrations of pumps and cars.  When hydrogen is detected, alarms sound through a wireless network.

If any one knows more about the “tiny internal source,” please let us know.  It sounds like nanotechnology and acoustics.  Applied Nanotech is also developing a photo-acoustic sensor.  Do not underestimate acoustic technology.  We are just beginning to rediscover what we once knew.  It is now believed that acoustic vibrations moved the mammoth stones that built the Egyptian pyramids.

Cavity Ring-Down Spectroscopy (CRDS)

Cavity “ring-down” spectroscopy sounds like acoustics.  It is the photonic technology applied by Tiger Optics to detect trace gases, including hydrogen, at fast speeds and highly sensitive levels. CRDS technology is based on the familiar semiconductor laser, with a few tricks and mirrors (Here is a good overview of CRDS technology).  One of the few other companies in this space is Picarro, a Stanford spin-off.  CRDS is not a nanotechnology, but a proven photonic technology whose potential is just beginning to be tapped, particularly in new laser architectures. It would be interesting to know how the CRDS laser performs in hydrogen detection relative to the emerging nanotechnologies; perhaps Rob Day over at Expansion Capital Partners can shed some light on this.