The Internet of things (IoT) has been rapidly growing in the past few years. IoT connects numerous devices, such as wireless sensors, actuators, and wearable devices, to optimize and monitor daily activities. Most of these devices require power in the microwatt range and operate indoors. To this end, a self-sustainable power source, such as a photovoltaic (PV) cell, which can harvest low-intensity indoor light, is appropriate. Recently, the development of highly efficient PV cells for indoor applications has attracted tremendous attention. Therefore, different types of PV materials, such as inorganic, dye-sensitized, organic, and perovskite materials, have been employed for harvesting low-intensity indoor light energy. Although considerable efforts have been made by researchers to develop low-cost, stable, and efficient PV cells for indoor applications, Extensive investigation is necessary to resolve some critical issues concerning PV cells, such as environmental stability, lifetime, large-area fabrication, mechanical flexibility, and production cost. To address these issues, a systematic review of these aspects will be highly useful to the research community. This study discusses the current status of the development of indoor PV cells based on previous reports. First, we have provided relevant background information. Then, we have described the different indoor light sources, and subsequently critically reviewed previous reports regarding indoor solar cells based on different active materials such as inorganic, dye-sensitized, organic, and perovskite. Finally, we have placed an attempt to provide insight into factors needed to further improve the feasibility of PV technology for indoor applications.

Mechanoluminescence platforms, combining phosphors with elastic polymer matrix, have emerged in smart wearable technology due to their superior elasticity and mechanically driven luminescent properties. However, their luminescence performance often deteriorates under extreme elastic conditions owing to a misinterpretation of polymer matrix behavior. Here, we unveil the role of the polymer matrices in mechanoluminescence through an interface-triboelectric effect driven by elasticity, achieving both high elasticity and brightness. By investigating interactions between elastic polymers and copper doped zinc sulfide microparticles, we reveal that elasticity significantly governed triboelectric effects for mechanoluminescence. In particular, high negative triboelectricity emerged as the key to overcoming poor triboelectric effect in extreme elastic conditions. This led to the discovery of polybutylene adipate-co-terephthalate silane and polycarbonate silane, achieving remarkable elasticity over 100% and a brightness of 139 cd/m². These findings offer fundamental insights to select the optimal polymer matrix based on systematic parameters for various smart wearable applications.

Smart biomaterials have significantly impacted human healthcare by advancing the development of medical devices designed to function within human tissue, mimicking the behavior of natural tissues. While the intelligence of biomaterials has evolved from inert to active over the past few decades, smart biomaterials take this a step further by making their surfaces or bulk respond based on interactions with surrounding tissues, imparting outcomes similar to natural tissue functions. This interaction with the surrounding tissue helps in creating stimuli-responsive biomaterials, which can be useful in tissue engineering, regenerative medicine, autonomous drug delivery, orthopedics, and much more. Traditionally, material engineering focused on refining the static properties of biomaterials to accommodate them within the body without evoking an immune response, which was a major obstacle to their unrestricted operation. This review highlights and explains various engineering approaches currently under research for developing stimuli-responsive biomaterials that tune their outcomes based on responses to bodily factors like temperature, pH, and ion concentration or external factors like magnetism, light, and conductivity. Applications in soft and hard tissue engineering, 4D printing, and scaffold design are also discussed. The advanced application of microfluidics, like organ-on-a-chip models, extensively benefits from the intrinsic smart properties of biomaterials, which are also discussed below. The review further elaborates on how smart biomaterial engineering could revolutionize biosensor applications, thereby improving patient care quality. We delineate the limitations and key challenges associated with biomaterials, providing insights into the path forward and outlining future directions for developing next-generation biomaterials that will facilitate clinical translation.

In this study, polyaniline (PAni)/poly(vinylidene fluoride) (PVDF) blends of different compositions were prepared by in situ chemical polymerization of aniline in a mixture of PVDF and dimethylformamide (DMF). Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetry (TG) and differential scanning calorimetry (DSC) were utilized to understand the effect of different amounts of in situ PAni loading on the crystalline structure, phase transition and dynamic melt-crystallization kinetics of PVDF. The images for morphology obtained using scanning electron microscopy and polarizing optical microscopy also provided the confirming evidences. FT-IR studies revealed that the transition of the crystalline structure (from β- to α-phase) of pure PVDF during recrystallization is hindered by the incorporation of PAni within the matrix. The dynamic crystallization kinetics data were analysed with different macroscopic models to describe the polymer crystallization, and the parameters obtained from the analyses were correlated with the structural evidence to verify their applicability for the systems under investigation. Values for the effective activation energy (E_X) of the crystallization process of PVDF and its blends were calculated by the differential isoconversional methods of Friedman. It was observed that, although PAni acted as an effective nucleating agent to induce a great number of heterogeneous nuclei within the blends, it actually delayed the overall crystallization process. The increased values of the crystal growth parameters obtained from the analysis of the temperature-dependent E_X by the modified Hoffman–Lauritzen theory also support the above mentioned interpretations.