The microsensor technology was used here to identify the initiation time of an impact shock. The shock excitation caused by an impact sphere with a diameter of 4-6 minimeters could generate transient elastic waves in concrete structures. Such elastic waves with frequency above 100 kHz are the active emission sources for defect detection in the non-destructive testing (NDT) of concrete using transient elastic waves. In this paper, an impact sphere, which was packaged with a piezoresistive microsensor, was fabricated to verify this new idea. The microsensor after packaging has the maximum output voltage of 100 mV and the rise time less than 5 microsecond subjected to a sphere impact. The promising result of the initiation time experiment showed that the calibrated (short circuit) signal was left behind the microsensor signal for 40 nanoseconds.
淡江理工學刊=Tamkang journal of science and engineering 5(3), pp.121-127