Development of an Implantable Capacitive Pressure Sensor for Biomedical Applications

Abstract

In this study, a subminiature implantable capacitive pressure sensor is proposed for biomedical applications. The proposed pressure sensor comprises an array of elastic silicon nitride (SiN) diaphragms formed by the application of a polysilicon (p-Si) sacrificial layer. In addition, using the p-Si layer, a resistive temperature sensor is also integrated into one device without additional fabrication steps or extra cost, thus enabling the device to measure pressure and temperature simultaneously. The sensor with a size of 0.5 × 1.2 mm was fabricated using microelectromechanical systems (MEMS) technology and was packaged in needle-shaped metal housing that is both insertable and biocompatible. The packaged pressure sensor immersed in a physiological saline solution exhibited excellent performance without leakage. The sensor achieved a sensitivity of approximately 1.73 pF/bar and a hysteresis of about 1.7%, respectively. Furthermore, it was confirmed that the pressure sensor operated normally for 48 h without experiencing insulation breakdown or degradation of the capacitance. The integrated resistive temperature sensor also worked properly. The response of the temperature sensor varied linearly with temperature variation. It had an acceptable temperature coefficient of resistance (TCR) of approximately 0.25%/°C.

Graphene resonant pressure sensor with ultrahigh responsivity-range product

“…The strain change due to the deformation can be measured by piezo-resistively * Author to whom any correspondence should be addressed. [3,4,[6][7][8], capacitively [9][10][11][12][13], optically [14][15][16] or by measuring the change in resonance frequency of a resonator fabricated on the diaphragm [5,17,18]. The piezoresistive and capacitive transduction schemes offer excellent responsivities over a short linear range [7,10].…”

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“…With the rapid development of the intelligent industry, wearable devices continue appearing in many aspects of people’s lives, greatly promoting the convenience, intelligence, and energy efficiency of healthy lifestyles, especially in areas such as motion monitoring, − health monitoring, − and voice monitoring, demonstrating great application potential. High-performance pressure sensors play an important role in the field of wearable devices.…”