SU-8 Guiding Layer for Love Wave Devices

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 densityviscosity and the physical adsorption and removal of protein was also assessed using albumin and fibrinogen as model proteins.

ST Quartz Acoustic Wave Sensors with Sectional Guiding Layers

“…Figure 3b shows the frequency change as a function of the square root of the viscosity density product comparing again an SSBW, Love wave and sectional guiding layer device having a 1 μm thick guiding layer. These data compare well to those previously reported for similar Love wave sensors [6, 13, 16]. …”

“…The frequency change as a function of gold thickness was obtained for nine different guiding layer thicknesses up to 1.8 μm after which the guiding layer was removed from the propagation path and the gold deposition repeated. The maximum sensitivity for the continuous guiding layer was found to be 269 Hz ng -1 mm -2 and sectional guiding layer 195 Hz ng -1 mm -2 both corresponding to a thickness of 1 mm; further increase in guiding layer thickness resulted in a gradual decrease in sensitivity being comparable to those previously reported for similar systems [13]. …”

“…Further increase in guiding layer thickness results in signal attenuation due to mass loading which are consistent with previous reports. [9, 13] The choice of guiding layer thickness effectively sets the operating point for the use as a sensor.…”

The Study of the Effects of Polishing Rotation Speed to the Length of Cut End Face SU-8 Polymer on Silicon Substrate

“…Oleh kerana itu, kebanyakkan perantiperanti yang terbaik dihasilkan dari bahan ini. Bahan ini turut digunakan dalam sistem mikroelektro-mekanikal (MEMS) (Schumacher et al 2008;Roach et al 2007;Chang 2009& Wen et al 2008, SU-8 fotorintangan (PR), modulator (Hyun 2003), peranti bendalir mikro (Roman et al 2006), mikro transduser (Wen 2006), Interferometer Sensor Ammonia (Bednorz et al 2006), MikroBiosensor Interferometer (Esinenco et al 2005) dan Interferometer Mach-Zehnder (Pelletier et al 2005). …”

Temperature Effects on the Propagation Characteristics of Love Waves along Multi-Guide Layers of Sio2/Su-8 on St-90°X Quartz

“…A SU-8 thin layer is proposed as guide layer, which exhibits low shear SH velocity, and benefits for the improvement of behavior and durability of a Love-type device when working as a viscosity sensor in liquid media [14,15]. …”