ABSTRACT
<p><b>OBJECTIVE</b>To design and build the micro-stress sensor measurement system for invisible aligner technique.</p><p><b>METHODS</b>A measurement system based on silicon-on-insulator piezoresistive stress sensor was developed. A four-point-bending based experimental apparatus was constructed to calibrate the piezoresistive coefficients of this stress sensor. A chemical-mechanical polishing process was developed for thinning the stress sensor dies. A packaging solution using flexible printed circuit to get signals out was designed.</p><p><b>RESULTS</b>The developed silicon stress sensor chip was 7.0 mm × 6.0 mm × 0.1 mm in size, and 13 sensor rosettes and 4 calibration rosettes were fabricated in one sensor. And a main testing PCB and a Lab View program were designed to carry out the automation measurement of the stress sensor. The stress state during the process was obtained through this test system. And measuered the stress of the 13 sensor unit.</p><p><b>CONCLUSIONS</b>A stress measurement system was established for measuring stress during orthodontic treatment with invisable aligner.</p>