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Stefanos Stavroulis, Roland Werthschützky
A Novel Overload Resistant Piezoresistive Silicon High Pressure Sensor
In state-of-the-art piezoresistive silicon pressure sensors the pressure is converted into an elastic deformation of the strongly tensioned silicon diaphragm. The resistance value of the implanted piezoresistors on the silicon diaphragm is affected by the mechanical tensions on the material. The etched silicon diaphragm exhibits a limited burst tension, so that common silicon pressure sensors with a diaphragm can only be utilised for pressures of 1000 bar. The novel sensor is based on a known disturbance effect. The pressure sensitive element is made of an unthinned silicon chip with piezoresistors on its upper surface and of a full-surface glass substrate (Pyrex) bonding connection on its bottom side. The different Young modulus of Silicon and Pyrex implies, under all-around sided-pressure load, mechanical tensions in the bounding surface between the two materials. These mechanical tensions in the silicon chip induce a change of the resistance value because of the piezoresistive effect. By optimisation of the conjunction of silicon and glass it is possible to utilise the elements for the middle pressure range between 100 and 3000 bar.
tm – Technisches Messen, Oldenbourg Wissenschaftsverlag
Print ISSN: 0171-8096
Volume: 70, 04/2003
Pages: 199