This paper presents a tri-band flexible wearable monopole antenna integrated with an electromagnetic bandgap (EBG) structure. The antenna uses a flexible PDMS (polydimethylsiloxane) substrate, with resonant frequencies at 2.45, 3.5, and 5.8 GHz, and operates within the frequency bands of 2.42–2.60 GHz, 3.11–3.70 GHz, and 5.32–6.81 GHz. To further optimize the antenna’s impedance matching and radiation characteristics, a defected ground structure is introduced in the design. Additionally, an EBG reflective surface is used to enhance reflection properties, reduce back radiation, improve antenna gain, and decrease the specific absorption rate (SAR). A 4 × 4 tri-band EBG array structure is integrated on the back of the monopole antenna, with each EBG unit consisting of two circular rings and a polygon, achieving zero reflection phase at 2.45, 3.5, and 5.8 GHz. The antenna demonstrates good impedance matching across the designed frequency bands, with a significant gain enhancement of 8.1, 6.64, and 8.21 dBi at the respective frequencies. Simulations with a human model show that the SAR values are below international standards within the operating frequency bands. The antenna also exhibits excellent robustness in its bent state, showing promising potential for applications in medical health monitoring.

This article presents a flexible wearable KIT monopole antenna for biomedical application. A metamaterial unit cell is proposed to improve the antenna performance. The proposed antenna and the metamaterial are fabricated on 1 mm-thick polydimethylsiloxane substrate to operate in the ISM frequency band of 2.45 GHz. Integration of the metamaterial improves the gain and reduces the specific absorption rate (SAR) of the antenna. The overall dimension of the antenna with the metamaterial is 49 × 49 × 19 mm3. The designed antenna is investigated for the loading effect of the body by placing on the hand phantom model. Bending tolerances are also analyzed for x and y direction with various bend radii. Gain and SAR of the proposed antenna are 4.61 dBi and 0.868 W/kg. The results of the fabricated prototype show that the proposed wearable antenna is safe for biomedical applications.

Adhesion between soft matter is a universal mechanical problem in bio-engineering and bio-integration. The Johnson–Kendall–Roberts (JKR) method is widely used to measure the work of adhesion and work of separation between soft materials. In this study, the JKR theory is recaptured and three complementary dimensionless parameters are summarized to help design adhesion measurement experiments compatible with the JKR theory. The work of adhesion/separation between two commonly used soft elastomers, polydimethylsiloxane (PDMS, Sylgard® 184) and Ecoflex® 0300, is measured by the JKR method using a dynamical mechanical analyzer. Effects of base polymer to curing agent mixing ratio and solvent extraction are examined. A unified adhesion mechanism is proposed to explain the different adhesion behaviors. It is concluded that chain–matrix interaction is the most effective adhesion mechanism compared with chain–chain or matrix–matrix interactions. Chain–chain interaction obstructs chain–matrix interaction as it either blocks or entangles with surface chains which could have interacted with the matrix.

Assays based on observations of the biological responses of individual cells to their environment have the potential to make enormous contributions to cell biology and biomedicine.To carry out well-defined experiments using cells, both the environments in which the cells live and the cells themselves must be well defined. Cell-based assays are now plagued by inconsistencies and irreproducibility, and a primary challenge in the development of informative assays is to understand the fundamental bases for these inconsistencies and to limit them. It now seems that multiple factors may contribute to the variability in the response of individual cells to stimuli; some of these factors may be extrinsic to the cells, some intrinsic. New techniques based on microengineering—especially using soft lithography to pattern surfaces at the molecular level and to fabricate microfluidic systems—have provided new capabilities to address the extrinsic factors. This review discusses recent advances in materials science that provide well-defined physical environments that can be used to study cells, both individually and in groups, in attached culture. It also reviews the challenges that must be addressed in order to make cell-based assays reproducible.