Implementation of ZnO Nanorods as Sensing Elements for a Surface Acoustic Wave Sensor

Abstract

The limited sensitivity of thinfilm based sensors has motivated the search for sensing structures and materials with greater sensing performance. Although thinfilm based SAW devices have been used as force, pressure, chemical and gas sensors so far. It is limited by the exposed sensing surface of the thinfilm. A feasibility study has been done by implementing the ZnO nanorods (NRs) to enhance the device sensitivity by greatly increase the exposed sensing surface. The implementation of these ZnO NRs as sensing elements is expected to enhance the sensing power due to the large surface to volume ratio. The sensing mechanism in this design is by detecting the minute change of seismic mass for ZnO NRs using surface acoustic wave before and after the attachment of reacting chemical liquid and gas substance.

Process development on synthesizing zinc oxide nanorods and fabrication of IDT finger electrodes for surface acoustic wave devices

“…One of the most intensively studied nanostructures is ZnO nanorods/nanowire which has the direct-band gap of 3.35 eV and the large excitation binding energy of 60 meV. Among the area of applications for ZnO nanorods including FET device, SET device, SAW device, solar battery, piezoelectric element, gas sensor, UV sensor, nanoscale-UV LEDs, and UV lasers [2,3]. Typically, ZnO nanorods are synthesized using thermal evaporation [4,5], chemical vapour deposition, or molecular beam epitaxial, which are vacuum and/or high temperature processes that require expensive equipments.…”

“…In addition, by introduction of ZnO nanoparticle, it also help to generate well-aligned ZnO nanorods structure [9]. Surface acoustic wave (SAW) or Rayleigh traveling wave devices have been demonstrated to be applicable in the fields that use force, pressure, chemical and gas as sensors [3]. To accomplish a perfect wave propagation mechanism, the interdigital transducer (IDT) finger needs to be fabricated.…”

Alignment nature of ZnO nanowires grown on polished and nanoscale etched lithium niobate surface through self-seeding thermal evaporation method

“…Accordingly, they are widely adopted as nanostructured sensing medium in chemical sensors [1][2][3][4][5]. For instance, 1-D ZnO nanostructures such as nanowires and nanorods have been used as sensing medium in acoustic wave devices like surface acoustic wave (SAW) devices [6][7][8][9][10][11] and quartz crystal microbalance (QCM) [12,13] for gas sensing and UV detection purposes. These kinds of acoustic devices are generally made of piezoelectric substrates such as quartz, lithium niobate, lithium tantalate, gallium orthophosphate and langasite.…”

Butane Sensing Property of Si-ZnO Nanowires p-n Junction

“…ZnO is an intrinsic and n-type direct wide bandgap semiconductor (3.35 eV) [11]. Up to date, ZnO NWs has been used as H 2 [12], CO [13], alcohol [14] and IPA [15] chemical and gas sensor. Most of the currently developed gas sensors are working at elevated temperature where extra energy is needed to heat up the sensing element to avoid sensor poisoning.…”