Aug 3 2010
In piezoresistive materials, mechanical stress influences the movement of charge available for conduction. The application of pressure to such materials translates into an easily measurable change in conductivity, making piezoresistives ideal for use in pressure and flow sensors.
Chee Chung Wong and co-workers from the A*STAR Institute of Microelectronics and Nanyang Technological University in Singapore have now demonstrated a method to increase the piezoresistive sensitivity of silicon nanowires using an applied electric field1.
Measuring the piezoresistive properties of silicon nanowires often requires the use of complicated instruments, such as atomic force microscopes, that can be used to apply stress and measure electrical properties simultaneously. Wong and his co-workers instead embedded silicon nanowires into the base of a large, 80 micrometer-long cantilever made of silicon dioxide (Fig. 1). Both the cantilever and nanowires could then be bent by a stylus, simplifying the measurement process. As a result, the researchers could combine the uniquely nanoscale piezoresistive response of the nanowires with the experimentally accessible, macroscale properties of a large cantilever without sacrificing the properties inherent to either length scale.
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