Inductively coupled microfluidic pressure meter for in vivo monitoring of cerebrospinal fluid shunt function

J Med Eng Technol. 2012 Apr;36(3):156-62. doi: 10.3109/03091902.2011.645943. Epub 2012 Feb 9.

Abstract

A microfluidic pressure sensor with inductively coupled, wireless readout capability has been developed for integration into cerebrospinal fluid shunt valve implants. The sensor consists of a deformable PDMS film that is bonded over a microfluidic reservoir, forming a fluidic capacitor. Deflection of the capacitor membrane is detected remotely through a shift in the resonance frequency of a micro-fabricated LC circuit. Sensors were fabricated by a combination of conventional MEMS technologies and rapid soft lithography. A direct pattern transfer technique was used to pattern the deformable PDMS film with a metal coating for the capacitive readout. The mechanical response of the fluidic capacitor was characterized by measuring the deflection of the PDMS film using an extrinsic Fabry-Perot interferometer (EFPI), and wireless sensing was demonstrated by the shift in resonance frequency of the sensor via an inductively coupled antenna. The sensor transduces pressure into a change in resonant frequency with sensitivity > 3.4 ppm Pa⁻¹ and responsivity 4.6 kHz Pa⁻¹, over a dynamic range of 0~3 kPa.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cerebrospinal Fluid Shunts / methods*
  • Dimethylpolysiloxanes
  • Equipment Design
  • Micro-Electrical-Mechanical Systems / instrumentation*
  • Microfluidic Analytical Techniques / instrumentation*
  • Monitoring, Physiologic / instrumentation*
  • Monitoring, Physiologic / methods*
  • Pressure
  • Transducers, Pressure
  • Wireless Technology / instrumentation

Substances

  • Dimethylpolysiloxanes
  • baysilon