SU-8 Guiding Layer for Love Wave Devices

Paul Roach, Shaun Atherton, Nicola Doy, Glen McHale, Michael I. Newton

Research output: Contribution to journalArticlepeer-review

Abstract

SU-8 is a technologically important photoresist used extensively for the fabrication of microfluidics and MEMS, allowing high aspect ratio structures to be produced. In this work we report the use of SU-8 as a Love wave sensor guiding layer which allows the possibility of integrating a guiding layer with flow cell during fabrication. Devices were fabricated on ST-cut quartz substrates with a single-single finger design such that a surface skimming bulk wave (SSBW) at 97.4 MHz was excited. SU-8 polymer layers were successively built up by spin coating and spectra recorded at each stage; showing a frequency decrease with increasing guiding layer thickness. The insertion loss and frequency dependence as a function of guiding layer thickness was investigated over the first Love wave mode. Mass loading sensitivity of the resultant Love wave devices was investigated by deposition of multiple gold layers. Liquid sensing using these devices was also demonstrated; water-glycerol mixtures were used to demonstrate sensing of density-viscosity and the physical adsorption and removal of protein was also assessed using albumin and fibrinogen as model proteins.
Original languageEnglish
Pages (from-to)2539-2547
Number of pages9
JournalSensors
Volume7
Issue number11
DOIs
Publication statusPublished - 1 Nov 2007

Keywords

  • love wave
  • SU-8
  • SU-8 guiding layer
  • SH-SAW

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