Piezoresistive strain gauges for use in wireless component monitoring systems

Wireless strain monitoring is a key part of helicopter component monitoring systems for rotating parts. Of particular interest are the pitch links, which control the angle of attack of the rotor blades. Because the pitch link is in constant motion, instrumenting these critical components is challenging. Wires cannot be easily run to areas where strains need to be measured. Thus, a wireless system must be able to run for extended periods on internal or harvested power. This places low power consumption as one of the top priorities for all parts of the system. This paper describes recent efforts in our group to design, fabricate and test piezoresitive strain gauges for wireless strain sensing applications. Relevant design parameters will be discussed, and the gauge design presented. Strain gauge test results will show the fabricated gauges response to loads on the order of 10 muepsiv, while dissipating only 14 muW of power.