Spiral-tube parylene intraocular pressure sensor

This paper presents the first biocompatible, all-mechanical, micromachined pressure sensor with a high-aspect-ratio spiral-tube structure fabricated through a one-layer parylene process. This passive sensor has zero power consumption and indicates the pressure variation by changes of in situ in-plane spiral rotation, which can be gauged externally by a direct and convenient optical observation. A 1 mm-radius device with a 10-turn spiral has demonstrated a 0.22 degree/mmHg sensitivity in liquid. This device is designed for eye implantation and the intraocular spiral rotation can be recorded from outside of the eye. Such a sensing technology is proposed to monitor the intraocular pressure in glaucoma patients.