We demonstrate the use of a phononic crystal to enable the nebulisation of liquid droplets from low-cost disposable arrays, using surface acoustic waves (SAW). The SAWs were generated using interdigitated transducers (IDT) on a piezoelectric surface (LiNbO(3)) and the acoustic waves were coupled into a disposable phononic crystal structure, referred to as a superstrate. Using its excellent reflecting properties, the phononic structures confined the acoustic field within the superstrate, resulting in the concentration of the acoustic energy, in a manner controllable by the excitation frequency. We show that this capability mitigates against coupling losses incurred by the use of a disposable superstrate, greatly reducing the time needed to nebulise a drop of water with respect to an unstructured superstrate for a given power. We also demonstrate that by changing the excitation frequency, it is possible to change the spatial position at which the acoustic energy is concentrated, providing a means to specifically nebulise drops across an array. These results open up a promising future for the use of phonofluidics in high-throughput sample handling applications, such as drug delivery or the "soft" transfer of samples to a mass spectrometer in the field of proteomics.

A top-down nanofabrication approach is used to develop silicon nanowires from silicon-on-insulator (SOI) wafers and involves direct-write electron beam lithography (EBL), inductively coupled plasma-reactive ion etching (ICP-RIE) and a size reduction process. To achieve nanometer scale size, the crucial factors contributing to the EBL and size reduction processes are highlighted. The resulting silicon nanowires, which are 20 nm in width and 30 nm in height (with a triangular shape) and have a straight structure over the length of 400 μm, are fabricated precisely at the designed location on the device. The device is applied in biomolecule detection based on the changes in drain current (Ids), electrical resistance and conductance of the silicon nanowires upon hybridization to complementary target deoxyribonucleic acid (DNA). In this context, the scaled-down device exhibited superior performances in terms of good specificity and high sensitivity, with a limit of detection (LOD) of 10 fM, enables for efficient label-free, direct and higher-accuracy DNA molecules detection. Thus, this silicon nanowire can be used as an improved transducer and serves as novel biosensor for future biomedical diagnostic applications.

No abstract

We demonstrate the use of surface acoustic wave nebulization (SAWN) to load optical traps. We show that the droplets sizes produced can be tuned by altering the RF frequency applied to the devices, which leads to more control over the sizes of trapped particles. Typically the size distribution of the liquid aerosols delivered using SAWN is smaller than via a standard commercial nebulization device. The ability to trap a range of liquids or small solid particles, not readily accessible using other ultrasonic devices, is also demonstrated both in optical tweezers and dual beam fiber traps.

Abstract. In fabricating Surface Acoustic Wave (SAW) biosensors device, the substrate is one of important factors that affected to performance device. there are many types of piezoelectric substrate in the markets and the cheapest is zinc Oxide substrate. Zinc Oxide (ZnO) with its unique properties can be used as piezoelectric substrate along with SAW devices for detection of DNA in this research. In this project, ZnO thin film is deposited onto silicon oxide substrate using electron beam evaporation (E-beam) and SolGel technique. Different material structure is used to compare the roughness and best piezoelectric substrate of ZnO thin film. Two different structures of ZnO target which are pellet and granular are used for e-beam deposition and one sol-gel liquid were synthesize and compared. Parameter for thickness of ZnO e-beam deposition is fixed to a 0.1kÅ for both materials structure and sol-gel was coat using spin coat technique. After the process is done, samples are annealed at temperature of 500C for 2 hours. The structural properties of effect of post annealing using different material structure of ZnO are studied using Atomic Force Microscopic (AFM) for surface morphology and X-ray Diffraction (XRD) for phase structure.