2021, Dong, Haiyun, Saggau, Christian Niclaas, Zhu, Minshen, Liang, Jie, Duan, Shengkai, Wang, Xiaoyu, Tang, Hongmei, Yin, Yin, Wang, Xiaoxia, Wang, Jiawei, Zhang, Chunhuan, Zhao, Yong Sheng, Ma, Libo, Schmidt, Oliver G.

Metal halide perovskites are promising materials for optoelectronic and photonic applications ranging from photovoltaics to laser devices. However, current perovskite devices are constrained to simple low-dimensional structures suffering from limited design freedom and holding up performance improvement and functionality upgrades. Here, a micro-origami technique is developed to program 3D perovskite microarchitectures toward a new type of microcavity laser. The design flexibility in 3D supports not only outstanding laser performance such as low threshold, tunable output, and high stability but also yields new functionalities like 3D confined mode lasing and directional emission in, for example, laser “array-in-array” systems. The results represent a significant step forward toward programmable microarchitectures that take perovskite optoelectronics and photonics into the 3D era. © 2021 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH.

2021, Zhu, Minshen, Zhu, Feng, Schmidt, Oliver G.

Skin mountable electronic devices are in a high-speed development at the crossroads of materials science, electronics, and computer science. Sophisticated functions, such as sensing, actuating, and computing, are integrated into a soft electronic device that can be firmly mounted to any place of human body. These advanced electronic devices are capable of yielding abilities for us whenever they are needed and even expanding our abilities beyond their natural limitations. Despite the great promise of skin mounted electronic devices, they still lack satisfactory power supplies that are safe and continuous. This Perspective discusses the prospects of the development of energy storage devices for the next generation skin mountable electronic devices based on their unique requirements on flexibility and miniaturized size.

2021, Zhu, Feng, Schmidt, Oliver G.

[No abstract available]

2020, Zhu, Minshen, Wang, Xiaojie, Tang, Hongmei, Wang, Jiawei, Hao, Qi, Liu, Lixiang, Li, Yang, Zhang, Kai, Schmidt, Oliver G.

Hydrogels are widely used in flexible aqueous batteries due to their liquid-like ion transportation abilities and solid-like mechanical properties. Their potential applications in flexible and wearable electronics introduce a fundamental challenge: how to lower the freezing point of hydrogels to preserve these merits without sacrificing hydrogels' basic advantages in low cost and high safety. Moreover, zinc as an ideal anode in aqueous batteries suffers from low reversibility because of the formation of insulative byproducts, which is mainly caused by hydrogen evolution via extensive hydration of zinc ions. This, in principle, requires the suppression of hydration, which induces an undesirable increase in the freezing point of hydrogels. Here, it is demonstrated that cooperatively hydrated cations, zinc and lithium ions in hydrogels, are very effective in addressing the above challenges. This simple but unique hydrogel not only enables a 98% capacity retention upon cooling down to −20 °C from room temperature but also allows a near 100% capacity retention with >99.5% Coulombic efficiency over 500 cycles at −20 °C. In addition, the strengthened mechanical properties of the hydrogel under subzero temperatures result in excellent durability under various harsh deformations after the freezing process. © 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

2021, Li, Fei, Li, Yang, Qu, Jiang, Wang, Jinhui, Bandari, Vineeth Kumar, Zhu, Feng, Schmidt, Oliver G.

The rapid development of wearable and portable electronics has dramatically increased the application for miniaturized energy storage components. Stamping micro-supercapacitors (MSCs) with planar interdigital configurations are considered as a promising candidate to meet the requirements. In this review, recent progress of the different stamping materials and various stamping technologies are first discussed. The merits of each material, manufacturing process of each stamping method and the properties of stamping MSCs are scrutinized, respectively. Further insights on technical difficulties and scientific challenges are finally demonstrated, including the limited thickness of printed electrodes, poor overlay accuracy and printing resolution.

2021, Striggow, Friedrich, Nadporozhskaia, Lidiia, Friedrich, Benjamin M., Schmidt, Oliver G., Medina-Sánchez, Mariana

Sperm-driven micromotors, consisting of a single sperm cell captured in a microcap, utilize the strong propulsion generated by the flagellar beat of motile spermatozoa for locomotion. It enables the movement of such micromotors in biological media, while being steered remotely by means of an external magnetic field. The substantial decrease in swimming speed, caused by the additional hydrodynamic load of the microcap, limits the applicability of sperm-based micromotors. Therefore, to improve the performance of such micromotors, we first investigate the effects of additional cargo on the flagellar beat of spermatozoa. We designed two different kinds of microcaps, which each result in different load responses of the flagellar beat. As an additional design feature, we constrain rotational degrees of freedom of the cell’s motion by modifying the inner cavity of the cap. Particularly, cell rolling is substantially reduced by tightly locking the sperm head inside the microcap. Likewise, cell yawing is decreased by aligning the micromotors under an external static magnetic field. The observed differences in swimming speed of different micromotors are not so much a direct consequence of hydrodynamic effects, but rather stem from changes in flagellar bending waves, hence are an indirect effect. Our work serves as proof-of-principle that the optimal design of microcaps is key for the development of efficient sperm-driven micromotors.

2021, Weng, Qunhong, Wang, Sitao, Liu, Lixiang, Lu, Xueyi, Zhu, Minshen, Li, Yang, Gabler, Felix, Schmidt, Oliver G.

Independent and well-packaged miniaturized energy storage devices (MESDs) are indispensable as power sources or backup units for integrated circuits and many dispersive electronics applications. Challenges associated with MESD development relate to their low packaged areal energy density and poor battery performance. Here, we propose a compact tube-in-tube battery configuration to overcome the areal energy density and packaging problems in microbatteries. Compact microtubular microelectrodes rolled up from patterned nanomembranes are sealed in an inert glass capillary with a thin tube wall. The resultant tube-in-tube microsized lithium-ion batteries (micro-LIBs), based on various active materials, exhibit very high and scalable packaged areal energy densities up to 605 microampere hours per square centimeter (μAh cm−2) or 313 μWh cm−2 with footprints as small as 0.39–0.79 mm2. This approach is a practical alternative for microbattery microelectrode, packaging, and configuration innovations.

2021, Li, Yang, Qu, Jiang, Li, Fei, Qu, Zhe, Tang, Hongmei, Liu, Lixiang, Zhu, Minshen, Schmidt, Oliver G.

Rechargeable microbatteries are important power supplies for microelectronic devices. Two essential targets for rechargeable microbatteries are high output energy and minimal footprint areas. In addition to the development of new high-performance electrode materials, the device configurations of microbatteries also play an important role in enhancing the output energy and miniaturizing the footprint area. To make a clear vision on the design principle of rechargeable microbatteries, we firstly summarize the typical configurations of microbatteries. The advantages of different configurations are thoroughly discussed from the aspects of fabrication technologies and material engineering. Towards the high energy output at a minimal footprint area, a revolutionary design for microbatteries is of great importance. In this perspective, we review the progress of fabricating microbatteries based on the rolled-up nanotechnology, a derivative origami technology. Finally, we discussed the challenges and perspectives in the device design and materials optimization.