MEMS Applications for Automotive Diagnostics

The problem that the proposed device/system addresses is the real time in-cylinder pressure and temperature measurement of internal combustion engines. The concept presented is for a multi-task sensor produced using MEMS technology that fits in thecylinder head adjacent to the gasket with its sensing element exposed in the cylinder to the combustion process. The fabrication process and design are proprietary information. The device is to be fabricated using technology derived to build planarstrain gauges that have thickness of between 20mm and 100mm. The same packaging solution that was used for the strain gauges is to be used for the pressure/temperature sensor. This allows the 'finished' devices to be in the 45mm to 125mm thickness range.As such, they can be fitted to an engine without the need to machine or redesign the engine. Subsequently, the device can be fitted to existing engines. Devices will be able to measure both temperature and pressure throughout a four-stroke cycle. Assuch, failure in valves, piston rings or the cylinder head gasket can be identified. The fabrication method (MEMS) in conjunction with the unique packaging solution ensures that the unit cost of the device is in the $5.00 range. All modern internalcombustion engines have management systems. None in the market have an in-cylinder pressure sensor, as the systems available do not meet reliability, installation and cost requirements that would make them viable. The proposed system meets theserequirements and as such has the potential to be a standard component in all internal combustion engines. As such, its potential commercial worth cannot be understated.