A batch fabricated capacitive pressure sensor with an integrated Guyton capsule for interstitial fluid pressure measurement

Teimour Maleki, Birck Nanotechnology Center, Purdue University
Benjamin Fogle, Birck Nanotechnology Center, Purdue University
Babak Ziaie, Birck Nanotechnology Center, Purdue University

Abstract

In this paper, we present the design, fabrication and test of a batch fabricated capacitive pressure sensor with an integrated Guyton capsule for interstitial fluid pressure measurement. The sensor is composed of 12 mu m thick single crystalline silicon membrane and a 3 mu m gap, hermetically sealed through silicon-glass anodic bonding. A novel batch scale method for creating electrical feed-throughs inside the sealed capacitor chamber is developed. The Guyton capsule consists of an array of 10 mu m diameter access holes etched onto a silicon back-plate separated from the silicon sensing membrane by a gap of 5 mu m. The presence of the Guyton capsule (i.e. plates with access holes plus the gap separating them from the sensing membrane) allows for the ingress of interstitial fluid inside the 5 mu m gap following the implantation, thus, providing an accurate measurement of interstitial fluid pressure. The fabricated sensor is 3 x 2 x 0.42 mm(3) in dimensions and has a maximum sensitivity of 10 fF mmHg(-1).

Discipline(s)

Nanoscience and Nanotechnology