We report a digital microfluidics platform based on floating liquid marbles.

This paper reports a wirelessly powered ionic polymer-metal composite (IPMC) soft actuator operated by external radio frequency (RF) magnetic fields for targeted drug delivery. A 183 μm thick IPMC cantilever valve was fitted with an embedded LC resonant circuit to wirelessly control the actuator when the field frequency is tuned to its resonant frequency of approximately 25 MHz. Experimental characterization of the fabricated actuator showed a cumulative cantilever deflection of 160 μm for three repeated RF ON–OFF cycles at 0.6 W input power. The device was loaded with a dye solution and immersed in DI water to demonstrate wireless drug release. The qualitative result shows the successful release of the dye solution from the device reservoir. The release rate can be controlled by tuning the RF input power. We achieved a maximum average release rate of ∼0.1 μl s⁻¹. We further conducted an in vitro study with human tumor cells (HeLa) to demonstrate the proof of concept of the developed device. The experiments show promising results towards the intended drug delivery application.

This review paper first discusses the design considerations that are being applied in the development of a highly sensitive, miniaturised and high throughput assay microcalorimeter. Major factors include reaction chamber, thermal insulation, fluid handling, mixing techniques and temperature sensing. Miniaturisation is the key to handle smaller sample volume within the nanoliter to picoliter regions, which is made possible by advancement in materials and fabrication technologies. Materials under review include silicon, silicon nitride, parylene-C, PMMA, PDMS, SU-8 and polyimide. The materials are compared in terms of size, cost, biocompatibility, chemical resistance and thermal properties. Finally, we compile the list of works across the globe and their contributions that demonstrated microcalorimeter prototypes with high thermal insulation, precise microfluidic handling capabilities, rapid mixing of fluids and high throughputs. This review offers broad perspectives and insights for those working on microcalorimeter, enthalpy arrays, microfluidic biosensor, thermal sensor and micromixer. Display Omitted

This paper describes recent advances in the design of RFID transponder. Nine architectures of RFID transponder IC are reviewed and compared. We also performed analysis of the circuit design techniques used for all building blocks on selected architectures, focusing on the advanced optimization techniques employed. Apart from that, future improvements for the transponder chip and other future trends in transponder design are also reviewed.

We present the mixing and merging of two reactive droplets on top of an open surface. A mobile droplet (1.0 M HCl solution + iron oxide particles) is magnetically-actuated to merge with a sessile droplet (1.0 M NaOH + phenolphthalein). The heat from the exothermic reaction is detected by a thermocouple. We vary the droplet volume (1, 5 and 10 μL), the magnet speed (1.86, 2.79, 3.72 and 4.65 mm/s) and the iron oxide concentration (0.010, 0.020 and 0.040 g/mL) to study their influences on the mixing time, peak temperature and cooling time. The sampled recording of these processes are provided as supplementary files. We observe the following trends. First, the lower volume of droplet and higher speed of magnet lead to shorter mixing time. Second, the peak temperature increases and cooling time decreases at the increasing speed of magnet. Third, the peak temperature is similar for bigger droplets, and they take longer to cool down. Finally, we also discuss the limitations of this preliminary study and propose improvements. These observations could be used to improve the sensitivity of the open chamber system in measuring the exothermic reaction of biological samples.