Acoustics have a wide range of uses, from noise-cancelling to ultrasonic imaging. There has been a surge in interest in developing acoustic-based approaches for biological and biomedical applications in the last decade. This review focused on the application of surface acoustic waves (SAW) based on interdigital transducers (IDT) for live-cell investigations, such as cell manipulation, cell separation, cell seeding, cell migration, cell characteristics, and cell behaviours. The approach is also known as acoustofluidic, because the SAW device is coupled with a microfluidic system that contains live cells. This article provides an overview of several forms of IDT of SAW devices on recently used cells. Conclusively, a brief viewpoint and overview of the future application of SAW techniques in live-cell investigations were presented.

Wearable sweat-sensing devices hold significant potential for non-invasive, continuous health monitoring. However, challenges such as ensuring data accuracy, sensor reliability, and measurement stability persist. This study presents the development of a wearable system for the real-time monitoring of human sweat sodium levels, addressing these challenges through the integration of a novel microfluidic chip and a compact potentiostat. The microfluidic chip, fabricated using hydrophilic materials and designed with vertical channels, optimizes sweat flow, prevents backflow, and minimizes sample contamination. The developed wearable potentiostat, as a measurement device, precisely measures electrical currents across a wide dynamic range, from nanoamperes to milliamperes. Validation results demonstrated accurate sodium concentration measurements ranging from 10 mM to 200 mM, with a coefficient of variation below 4% and excellent agreement with laboratory instruments (intraclass correlation = 0.998). During physical exercise, the device measured a decrease in sweat sodium levels, from 101 mM to 67 mM over 30 min, reflecting typical physiological responses to sweating. These findings confirm the system’s reliability in providing continuous, real-time sweat sodium monitoring. This work advances wearable health-monitoring technologies and lays the groundwork for applications in fitness optimization and personalized hydration strategies. Future work will explore multi-biomarker integration and broader clinical trials to further validate the system’s potential.

The conventional photolithography of crystalline silicon techniques is limited to two-dimensional and structure scaling. This can be overcome by using laser micromachine, a technique capable of producing three-dimensional structure and simultaneously avoiding the needs for photomasks. In this paper, we report on the use of RapidX-250 excimer laser micromachine with 248 nm KrF to create in-time mask design and assisting in the fabrication of micro-cantilever structure. Three parameters of the laser micromachine used to aid the fabrication of the micro-cantilever have been investigated; namely the pulse rate (i.e. number of laser pulses per second), laser energy and laser beam size. Preliminary results show that the 35 um beam size and 15 mJ energy level is the most effective parameter to structure the desired pattern. The parallel lines spacing of the structure can be reached up to 10 um while cutting, holes drilling and structuring the cantilever using the laser beam can be accomplished to as low as 50 um in dimension.

A surface acoustic wave (SAW) sensor detects changes in physical properties such as mass and density on its surface. Compared to other types of sensors, SAW sensor have a good stability, high selectivity and sensitivity, fast response, and low-cost. On the other hand, to design and optimize a SAW biosensor requires a long process including time and cost using conventional methods. Therefore, numerical simulation and computational modelling are useful and efficiently conduct analysis for the SAW biosensor. In this paper, a numerical simulation technique is used to analyse the SAW device sensitivity for the application of gas detection. The SAW biosensor can detect very small mass loading by changing its sensor resonance frequency. The two-dimensional (2D) device model is based on a two-port SAW resonator with a gas sensing layer. We made two design of SAW biosensor device with frequency of 872 MHz and 1.74 GHz. A gas with vary concentration from 1 to 100 ppm were used to determine the change of the device resonance frequency. As a result, the high frequency (1.74 GHz) device, shows that the resonance frequency is shifted larger than to the low frequency (872 MHz) device. In addition, the high frequency device offers five times more sensitivity than the low frequency device. By changing the sensor design, the sensor characteristics such as sensitivity can be altered to meet certain sensing requirements. Numerical simulation provides advantages for sensor optimization and useful for nearly representing the real condition.

Biosensor is an analytical device that consists of immobilized biological sensitive materials. When these materials are in contact with certain transducers, the sensor is able to convert biological signal into electrical signal, hence allowing for certain measurement to be conducted. These sensors have the capability to detect certain human traits such as DNA, tissues, enzyme, antibody and antigen. To increase the biosensor performance especially the interaction between the sensor and biological elements, high uniformity and good optical transmittance sensors are strongly important. Therefore, this paper will presents early characterization of biosensors using Zinc Oxide (ZnO) piezoelectric thin film deposited as sensing layer on Silicon substrate. We investigated the thin film surface morphology and optical characterization using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and UV-Visible Spectrophotometer. We found that the surface roughness of the thin film varied from 1.1 nm to 4.5 nm and the grain size increased with the increase of annealing temperature thus provide high surface uniformity that will enhance the sensitivity and specificity of the sensor.