Optimization of LC sensor enabling wireless passive intracranial pressure monitoring

With the increasingly widespread researches of wireless passive sensing technology based on LC sensors in the field of intracranial pressure (ICP) monitoring and other biomedical applications, the importance of sensor optimization has become increasingly prominent. This paper presents an optimization method of LC sensor enabling wireless passive ICP monitoring. The LC sensor is a resonant tank formed by a pressure-sensitive capacitor and a fixed inductor. The parameters of the capacitor and the inductor are optimized based on four optimization criteria: maximizing sensitivity, setting anodic bonding voltage less than pull-in voltage, maximizing quality factor and setting an upper limit of resonant frequency. Among them, the pull-in voltage is a critical value when pull-in effect occurs during anodic bonding, a key step in the process of capacitor fabrication. To analytically calculate the pull-in voltage, a pull-in effect model is built, and its effectiveness is verified by simulation and experiment. Based on the above-mentioned optimization criteria, the LC sensor is optimized, fabricated and characterized. The experimental results show that the optimized sensor achieves competitive sensitivity, quality factor and resonant frequency compared with the previous reports, and illustrate the effectiveness of the optimization method enabling ICP monitoring.