Microscopic Optical Acoustic Sensors for Intracranial Measurements

Optical acoustic sensors provide a potential means for making accurate intracranial pressure measurements. Complex cranial geometries consisting of bone, tissue, and fluid filled spaces pose problematic conditions for the use of conventional acoustic sensors. This research investigates the potential limitations of previously devised optical acoustic sensors in addition to introducing a novel procedure utilizing micro-scale additive manufacturing to fabricate such sensors with a bandwidth on the order of 20kHz to 200kHz. The significance of individual parameters describing the sensor geometry are discussed as a basis for developing sensors with desired characteristics. Results are obtained through finite element modeling comparing mechanical sensitivities and frequency response arising from diaphragm geometric design and optical fiber positioning within a sensor body. Fabrication techniques and sensor performance are reported.