The current study focuses on the manufacturing and characterization of various forms of Ecoflex and their composites to improve the mechanical properties and surface texture, specifically for use in wearable sensors and electronic skin applications. Various types of Ecoflex elastomers were mixed to form blended composite materials, which could be used to tune the mechanical properties. Experimental and simulation methods were conducted to understand the mechanical behavior and material properties of the manufactured samples under large deformation (1200% strain) by various dynamic loading conditions. Further, the surface conditions of specimens were analyzed and evaluated using scanning electron microscopy and contact angle goniometer. The Yeoh model reasonably predicts the viscoelastic and hysteresis behavior of Ecoflex and its composites in accordance with the experimental data for small and large strain. The surface smoothness and moisture-resistant properties of the material surface were enhanced up to a contact angle of 127° (maximum) by adding x = 15 wt% of surface tension diffusers, with a slight compromise in stretchability. This comprehensive investigation and database of Ecoflex–Ecoflex composite can guide and help researchers in selecting and applying the most appropriate Ecoflex/blended solutions for a specific application, while providing insight into the mechanics of materials of blended materials.

Polymer–ceramic piezoelectric composites offer a promising solution for applications requiring flexible, lightweight materials with enhanced electromechanical properties. By combining the flexibility of polymers with piezoelectric ceramics, these composites can exhibit superior dielectric and piezoelectric behavior, making them ideal for use in sensors, actuators, and energy harvesting devices. In the present study, poly (vinylidene fluoride) (PVDF) was reinforced with 2–10 wt.% of aluminum nitride (AlN) nanoparticles to enhance its thermal and piezoelectric properties, which is important for integration with microelectromechanical systems manufacturing and applications. X-ray diffraction revealed the formation of polar-phase PVDF, with improved crystallinity due to the nucleating effect of AlN nanoparticles. Dielectric measurements, performed across various frequencies and temperatures, showed that AlN improved the thermal stability of PVDF, making it more suitable for use in electronic films at elevated temperatures. Furthermore, the poled nanocomposite with 10 wt.% of AlN showed a higher d ₃₃ value of 16.3 pC N⁻¹, and maintained a higher piezoelectric performance, compared to pristine PVDF (6.5 pC N⁻¹), under similar thermal conditions. Moreover, the fabricated PVDF/10AlN nanocomposite energy harvesting device displayed a higher peak-to-peak voltage of ∼26.6 V and a peak power density of 9.9 μW cm⁻² under an applied force. Consequently, the nanocomposite device maintained a stable piezoelectric performance at higher temperatures, demonstrating its potential for practical energy harvesting applications at elevated temperatures.

The integration of high-frequency acoustic waves with microfluidics has been gaining popularity as a method of separating cells/particles. A standing surface acoustic wave (sSAW) device produces constructive interference of the stationary waves, demonstrating an increase in cell separating efficiency without damaging/altering the cell structure. The performance of an sSAW device depends on the applied input signal, design of the IDT, and piezoelectric properties of the substrate. This work analyzes the characteristics of a validated 3D finite element model (FEM) of LiNbO₃ and the effect on the displacement components of the mechanical waves under the influence of sSAWs by considering XY-, YX-, and 128⁰ YX-cut LiNbO₃ with varying electrode length design. We demonstrated that device performance can be enhanced by the interference of multiple waves under a combination of input signals. The results suggest that 128⁰ YX-cut LiNbO₃ is suitable for generating higher-amplitude out-of-plane waves which can improve the effectiveness of acoustofluidics-based cell separation. Additionally, the findings showed that the length of the electrode impacts the formation of the wavefront significantly.

Since its introduction, vaccination has heavily improved health outcomes. However, implementing vaccination efforts can be challenging, particularly in low and middle-income countries with warmer climates. Microneedle technology has been developed for its simple and relatively painless applications of vaccines. However, no microneedle vaccine has yet been approved by the FDA. A few hurdles must be overcome, including the need to evaluate the safety and biocompatibility of the polymer used to fabricate these microneedles. Additionally, it is important to demonstrate reliable immune responses comparable to or better than those achieved through traditional administration routes. Scalability in manufacturing and the ability to maintain vaccine potency during storage and transportation are also critical factors. In this study, we developed vaccine-loaded dissolvable microneedles that showed preclinical immunogenicity after storage in extreme conditions. We developed our microneedles using the conventional micromolding technique with polyacrylic acid (PAA) polymer, incorporating a novel virus-like particle (VLP) vaccine targeting arboviruses. We performed characterization studies on these microneedles to assess needle sharpness, skin insertion force, and VLP integrity. We also investigated the thermostability of the vaccine after storing the microneedles at elevated temperatures for approximately 140 days. Finally, we evaluated the immunogenicity of this vaccine in mice, comparing transdermal (microneedle) with intramuscular (hypodermic needle) administration. We successfully fabricated and characterized VLP-loaded microneedles that could penetrate the skin and maintain vaccine integrity even after exposure to extreme storage conditions. These microneedles also elicited robust and long-lasting antibody responses similar to those achieved with intramuscular administration.

Microelectromechanical Systems (MEMS) energy harvesters have been extensively investigated over the past decade, but increasing power density and long-term reliability under high acceleration and low frequency are still major concerns. This study focused on the development of a low-frequency lead zirconate titanate (PZT) based energy harvester capable of operating at high acceleration >4 g with high power density performance. This study investigates the performance effects of altering the electrode configuration and poling configuration to maximize power density. The study investigated using four different types of electrode configuration consisting of long and short interdigitated electrodes (IDE) to operate in d 33 mode, and traditional parallel plate configuration to operate in d 31 mode. The results were numerically and experimentally validated. The results illustrate that the d 33 mode configuration was able to generate >3200 μW mm ^-3 with good reliability of up to 4 g.