Silicon microfabrication based particulate matter sensor

With the increasing public awareness of the impact of particulate matter (PM) on human health, real-time monitoring of PM exposure level has attracted more interest than ever before. While a great deal of effort has been put into the miniaturization of PM sensors, a wider range of applications is still hindered by big form factor and high cost. In this paper a novel design of PM sensor based on silicon microfabrication is presented. Silicon microfabrication and assembly process enables relatively small form factor and low cost. The operation principle of the sensor is light scattering method, an indirect way of measuring PM concentration. Silicon-based microfluidics serve as air flow channel and provide sealed sensing chamber for collecting scattered light by aerosol particles. The main chip components are integrated in the form of bare dies, reducing the size of the whole system. The main body of the sensor possesses small size of 15 × 10 × 1 mm3, enabling easy integration into portable and wearable electronics. The light source in the sensor consumes less than 5 mW of power and the total power consumption is still low enough to make it suitable for battery-powered devices. In-lab and field testing and calibration results have shown that the sensor can achieve an accuracy of less than 10 μg/m3 and prompt response (within s) to particle concentration changes. Detailed design, fabrication as well as testing results will be explained in this paper.