Feb 5, 2009
Bimetallic strip inspires nanoscale thermometer
The coiled bimetallic strip thermometer has been in use for more than 200 years and can be seen today in the form of common household thermostats and cooking thermometers. Now, researchers led by professor Jr-Hau He from National Taiwan University, have taken the idea to the nanoscale by creating a bimorph structure out of ZnO nanobelts and plasma-polymerized benzonitrile.
The device features a new readout technique based on the change in the electric current flowing through the bimorph and the contact pad. Various read-out techniques such as laser-beam deflection, interferometry, piezoresistive, piezoelectric, capacitance, and field-effect transistors have been exploited to detect bimorph deflections, but these methods typically involve either complex fabrication steps or time consuming optical alignment.
"The thermal sensor demonstrated here is a strong candidate for thermal switching and triggered detection thanks to the relative ease of fabrication and the direct electrical readout," said Jr-Hau He. "We believe that the theoretical and experimental understanding gained from the present research will facilitate sensors/switches at the nanoscale for applications such as thermal control in nanoelectronics and nanothermal probing."
The device architecture suits thermal imaging or switching in an arrayed manner. In addition, the technology can be adapted to realize a highly sensitive chemical and biological sensing system by altering the sensitive layer.
This research is a result of the collaboration between National Taiwan University, Taiwan, and Georgia Institute of Technology, USA.
The researchers presented their work in Nanotechnology.
About the author
Chih H Ho is a research assistant in Small Lab led by Prof. Jr-Hau He at the Institute of Photonics and Optoelectronics, and the Department of Electrical Engineering, National Taiwan University, Taiwan. Small Lab is currently exploring 1D nanostructures, together with electrical and optoelectronic measurement, and application of the resulting nanostructures. Srikanth Singamaneni, Yen-Hsi Lin and Michael E McConney are graduate students in the Surface Engineering and Molecular Assemblies (SEMA) Lab led by Prof. Vladimir V Tsukruk at Georgia Institute of Technology.