Hybrid Miniature Fabry-Perot Sensor with Dual Optical Cavities for Simultaneous Pressure and Temperature Measurements

We present a novel hybrid miniature dual-cavity Fabry-Perot sensor for simultaneous pressure and temperature measurements. The pressure sensing cavity is composed of an UV-molded cavity covered by a metal/polymer composite diaphragm for achieving a high pressure sensitivity while maintaining a miniature sensor size. Another intrinsic polymer/silica cavity is adopted for temperature sensing, which enables a high temperature sensitivity even with a short cavity length due to the large thermal expansion of the polymer. The sensor is fabricated by using a unique UV molding process with simple and safe procedures. The overall sensor size is around 150 mu m in diameter and 343 mu m in length. Experimental studies show that the sensor exhibits a good linearity over a pressure range of 6.89 to 27.58 kPa with a pressure sensitivity of 0.0122 mu m/kPa at 26 degrees C, and a temperature range of 26.0 degrees C to 50.0 degrees C with a temperature sensitivity of 0.0029 mu m/degrees C. An optical signal processing method is developed to retrieve the two cavity length changes, which is demonstrated to have a better resolution and a faster speed than the conventional method. The sensor is expected to benefit many fronts that require simultaneous pressure and temperature measurements with minimum intrusiveness, especially for biomedical applications.