Wireless Passive Intracranial Pressure Sensor Based on a Microfabricated Flexible Capacitor

This paper presents a wireless passive pressure sensor based on a microfabricated flexible pressure-sensitive capacitor specifically designed to monitor intracranial pressure (ICP) in patients with traumatic brain injuries. The flexible pressure-sensitive capacitor is featured by creatively utilizing the PDMS wrinkles spontaneously generated during PDMS etching to construct a cavity structure for sensitivity improvement. Moreover, a flexible reader coil used for signal readout was optimized to perform better coupling with the sensor in a large enough detection range for ICP monitoring. In addition, the flexible pressure-sensitive capacitor is capable of conforming to curved topographies of skulls and dura maters due to its flexible character and thin thickness. The experimental results show that the proposed sensor reaches a lower resonant frequency, a higher quality factor, and a better sensitivity, compared with previous reports. The abovementioned flexible character and favorable performances make the proposed sensor a potential candidate for the future application in ICP monitoring.