Patterning Techniques in Coplanar Micro/Nano Capacitive Sensors.

Rapid technological advancements have led to increased demands for sensors. Hence, high performance suitable for next-generation technology is required. As sensing technology has numerous applications, various materials and patterning methods are used for sensor fabrication. This affects the characteristics and performance of sensors, and research centered specifically on these patterns is necessary for high integration and high performance of these devices. In this paper, we review the patterning techniques used in recently reported sensors, specifically the most widely used capacitive sensors, and their impact on sensor performance. Moreover, we introduce a method for increasing sensor performance through three-dimensional (3D) structures.

Eco-Friendly Keratin-Based Additives in the Polymer Matrix to Enhance the Output of Triboelectric Nanogenerators.

A triboelectric nanogenerator (TENG) is an energy generator that converts mechanical energy into electrical energy using triboelectricity at a nanoscale. Given their potential application as power sources in electronic devices, various attempts have been made to improve their output performance. Here, we present an eco-friendly, low-cost, and facile fabrication method to enhance TENG characteristics with keratin protein additives. Keratin sources, human and cat hair, are processed into powder and added to the friction layer, which increases their positive charge affinity, thereby boosting the output performance of the TENG. The output performances of the keratin-added TENG (K-TENG) are measured in the vertical contact-separation mode, with both additives having the highest output values at 5 wt % load. The K-TENG generates more output voltage and current values than the pristine TENG by 90 and 208%, respectively. Hence, we conclude that this method would potentially promote TENG as a strong candidate for a competitive "green" energy harvesting device in future electronics applications.

Intaglio Contact Printing of Versatile Carbon Nanotube Composites and Its Applications for Miniaturizing High-Performance Devices.

Composites based on carbon nanotubes (CNTs) are promising patternable materials that can be engineered to incorporate the outstanding properties of CNTs into various applications via printing technologies. However, conventional printing methods for CNTs require further improvement to overcome the major drawbacks that limit the patterning resolution and target substrate. Herein, an intaglio contact printing method based on a CNT/paraffin composite is presented for realizing highly precise CNT network patterns without restrictions on the substrate. In this method, the CNT/paraffin composite can be patterned with a high resolution (<10 µm) and neatly transferred onto various substrates with a wide range of surface energies, including human skin. The patterned composite exhibits high durability against structural deformations, and structural damage caused by fatigue accumulation can be cured in a few seconds. In addition, miniaturized sensing and energy-harvesting applications are demonstrated with high performances. The present method facilitates the rapid fabrication of highly precise interdigitated electrodes via one-step printing, enabling high-performance operation and miniaturization of the devices. It is anticipated that these results will not only spur the further development of various applications of CNTs but also contribute to advances in soft lithography methods applicable to many fields of science and engineering.