D6.3 - Wireless Sensor System for Monitoring Spatially Resolved Tongue Pressure

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings SENSOR 2011
D6 - Medical I
I. Stöhr, G. Schuster, R. Werthschützky - Technische Universität Darmstadt (Germany)
628 - 633


Orthodontist are interested in the position and pressure of the tongue against the hard palate since it has influence on many functions like speaking, swallowing and the growth of the mandible. In the past some efforts were made, to measure the tongue pressure and its spatial distribution. But al these devices incorporate wires or tubes connecting the intra-oral measuring device to an extra-oral data acquisition electronics, thus disturbing the natural function of tongue and lips.

Main goal of the developed sensor system is to minimize the disturbance of the patient by the system. Therefore a wireless data transmission and a data acquisition circuit have to be integrated into the intra-oral device. Sensors and electronics have to be as thin as possible to minimize disturbance.

The system consist of eight miniaturized piezoresistive silicon pressure sensors (SM5108, Silicon Microstructures), an integrated analog front end circuit, including multiplexer, amplifier and delta-sigma ADC (AD7194, Analog Devices), a ZigBee compliant transceiver (ATVB-24-A2, Atmel), a 60 mAh LiPo battery for power supply and an Atmel ATmega168PA microcontroller. All components are mounted in a vacuum formed upper plate.

Due to the very limited power supply and the fact, that the eight sensors themselves draw 5,28 mA at 3,3 V supply, special concepts for sensor readout were developed. The sensors are only powered up during readout. Thermal and electrical settlement of sensor output and effects on accuracy are investigated. Power consumption of the sensors could be reduced by 97 %.

The paper describes development of the wireless sensor system, power demand of the main components and measures to reduce power consumption are discussed. Test results in a lab environment and a first test on a test subject are presented.