Microfibers have received much attention due to their promise for creating flexible and highly relevant tissue models for use in biomedical applications such as 3D cell culture, tissue modeling, and clinical treatments. A generated tissue or implanted material should mimic the natural microenvironment in terms of structural and mechanical properties as well as cell adhesion, differentiation, and growth rate. Therefore, the mechanical and biological properties of the fibers are of importance. This paper briefly introduces common fiber fabrication approaches, provides examples of polymers used in biomedical applications, and then reviews the methods applied to modify the mechanical and biological properties of fibers fabricated using different approaches for creating a highly controlled microenvironment for cell culturing. It is shown that microfibers are a highly tunable and versatile tool with great promise for creating 3D cell cultures with specific properties.

Transient Li‐ion batteries based on polymeric constituents are presented, exhibiting a twofold increase in the potential and approximately three orders of magnitude faster transiency rate compared to other transient systems reported in the literature. The battery takes advantage of a close variation of the active materials used in conventional Li‐ion batteries and can achieve and maintain a potential of >2.5 V. All materials are deposited form polymer‐based emulsions and the transiency is achieved through a hybrid approach of redispersion of insoluble, and dissolution of soluble components in approximately 30 min. The presented proof of concept has paramount potentials in military and hardware security applications. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 2021–2027

Triboelectric nanogenerators (TENGs) can directly harvest energy via solid–liquid interface contact electrification, making them very suitable for harvesting raindrop energy and as active rainfall sensors. This technology is promising for realizing a fully self-powered system for autonomous rainfall monitoring combined with energy harvesting/sensing. Here, we report a raindrop energy-powered autonomous rainfall monitoring and wireless transmission system (R-RMS), in which a raindrop-TENG (R-TENG) array simultaneously serves as a raindrop energy harvester and rainfall sensor. At a rainfall intensity of 71 mm/min, the R-TENG array can generate an average short-circuit current, open-circuit voltage, and maximum output power of 15 μA, 1800 V, and 325 μW, respectively. The collected energy can be adjusted to act as a stable 2.5 V direct-current source for the whole system by a power management circuit. Meanwhile, the R-TENG array acts as a rainfall sensor, in which the output signal can be monitored and the measured data are wirelessly transmitted. Under a rainfall intensity of 71 mm/min, the R-RMS can be continuously powered and autonomously transmit rainfall data once every 4 min. This work has paved the way for raindrop energy-powered wireless hyetometers, which have exhibited broad prospects in unattended weather monitoring, field surveys, and the Internet of Things.

Application of gel polymer electrolytes (GPE) in lithium-ion polymer batteries can address many shortcomings associated with liquid electrolyte lithium-ion batteries. Due to their physical structure, GPEs exhibit lower ion conductivity compared to their liquid counterparts. In this work, we have investigated and report improved ion conductivity in GPEs doped with ionic liquid. Samples containing ionic liquid at a variety of volume percentages (vol %) were characterized for their electrochemical and ionic properties. It is concluded that excess ionic liquid can damage internal structure of the batteries and result in unwanted electrochemical reactions; however, samples containing 40–50 vol % ionic liquid exhibit superior ionic properties and lower internal resistance compared to those containing less or more ionic liquids.

unique attribute of transient electronics is that they are designed to operate over a typically short and predefined duration of time and disintegrate fully or partially when no longer needed.This concept can be applied to a number of different systems, including implantable biomedical devices, [1,2] environmental sensors, [3,4] and hardware security, [5,6] to name a few examples. Transient implantable biomedical devices could be designed to degrade within the body after a predefined period of reliable operation; this will eliminate the need for secondary surgery needed to extract the device. Transient environmental sensors made of environmentally friendly (green) and degradable polymers could be utilized to collect various types of data such as humidity and pressure, then be absorbed into the environment, minimizing bulk waste that is harmful to wildlife, such as birds and fish. And last, transient hardware-secured devices could undergo disintegration, making sensitive information irretrievable upon degradation.Research in transient electronics started with the integration of conventional electronic components on a degradable substrate and was followed by the integration of partially transient electronic components and a few fully degradable components. [7][8][9] The most recent form of transient electronics, however, is fully transient. [10][11][12][13][14] To date, researchers have successfully synthesized and designed material systems and transiency mechanisms that allow electronic devices with functionality and performance level of the conventional counterparts, and yet capable of undergoing disintegration once needed.This short review will report on the materials used in transient electronics, mechanisms that facilitate transiency, manufacturing techniques of this class of electronics, and transient electronic devices developed so far and their potential applications. Transient MaterialsStructural components of electronics, in general, consist of a substrate that acts as the mechanical support and electronic components that are responsible for the functionality of the system. In the case of transient electronics, all the constituents must be capable of dissolution or disintegration to facilitate