Smart brush based on a high density CMOS stress sensor array and SU-8 microposts

This paper reports on a CMOS integrated stress sensor array combined with SU-8 posts fabricated on the chip surface. The chip contains an array of 1024 field effect transistor (FET)-based stress sensors occupying a total area of ca. 1 x 1 mm². On-chip circuitry is used for sensor addressing, signal amplification, A/D conversion, signal processing, and serial bus communication. A novel scalable matrix-based sensor selection concept enables the integration of high-density stress sensor arrays with minimum wiring. The system significantly expands previous stress sensor arrays in terms of an increased number of sensors and reduced sensor pitch. An array of 8 x 8 circular SU-8 posts with a diameter of 62 mum and a height of 300 mum was fabricated on the CMOS chips. The new brush-like device was used for measuring vertical and horizontal force distributions.