A stainless-steel-based implantable pressure sensor chip and its integration by microwelding

Xing Chen, Daniel Brox, Babak Assadsangabi, Mohamed Sultan Mohamed Ali, Kenichi Takahata

Research output: Contribution to journalArticlepeer-review

Abstract

A stainless-steel (SS) chip of capacitive pressure sensor and its integration method are developed with a focus on smart implant applications. The sensors are entirely microfabricated with biocompatible materials, through thermal bonding of gold-polyimide diaphragm film to the chip dies made of medical-grade SS. The reference cavity design with dead-end holes created in the SS die is both theoretically and experimentally verified to enhance pressure sensitivity. Laser microwelding is investigated as an alternative integration path for this type of SS-based sensors to establish permanent and reliable bond onto SS-based platform devices. The microwelded bond is revealed to provide twice the mechanical strength and ∼6 × electrical conductance compared with a conventional conductive epoxy case. The microwelded sensors exhibit an average sensitivity of 110 ppm/mmHg close to its pre-welding level. The microwelding integrations of fabricated chips with the SS antenna stent and hypodermic needle are demonstrated. The results suggest not only that the developed pressure sensor is compatible with laser microwelding, but also that micowelding is a promising packaging technique for SS-based biomedical and implant microdevices that require long-term bond reliability.

Original languageEnglish (US)
Pages (from-to)134-144
Number of pages11
JournalSensors and Actuators, A: Physical
Volume257
DOIs
StatePublished - Apr 15 2017

Keywords

  • Biomedical microdevices
  • Capacitive pressure sensor
  • Laser microwelding
  • Smart implants
  • Stainless steel

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering

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