Triboelectric generators (TEGs) or triboelectric nanogenerators (TENGs) are energy generating devices that can convert mechanical energy into electrical energy. The principle is based on the triboelectric effect and electrostatic induction between two triboelectric surfaces, following a cycling contact–separation mode of two triboelectric materials. The triboelectric materials can be metal, non-metal, or compound materials, which can be electrically charged by contact and friction with other triboelectric materials. The output performance of the TEG/TENG strongly depends on the contact area and friction between the two triboelectric materials, which, in the limited area of two triboelectric surfaces, are strongly related to morphology.
In a recent Full Paper in Small, Van-Long Trinh and Chen-Kuei Chung from the National Cheng Kung University, Taiwan, demonstrate a facile method and novel mechanism using microneedle (MN)-structured polydimethysiloxane (PDMS) for TEG/TENG applications, which can convert wasted mechanical energy into electricity.
The MN-TEG is a TEG device consisting of an aluminum foil and microneedle-structured polydimethylsiloxane (MN-PDMS) film. A simple, low-cost, rapid-fabrication method using CO2 laser ablation on a polymethyl methacrylate master mold and molding process is used.
The MN-PDMS has a great increase in randomly closed bending–friction–deformation behavior of the MNs that highly enhances triboelectric performance of the MN-TEG. By hand tapping, the new high-aspect-ratio MN-TEG can generate a high output performance with an open-circuit voltage up to 102.8 V and a short-circuit current of 43.1 mA, corresponding to a current density of 1.5 mA cm-2. The MN-TEGs durable mechanical working was confirmed over 500 min, that is, more than twenty-times tapping of 1500 sec stable electric power generation. The output energy of the MN-TEG can be stored in capacitors with fast charging and high charging voltage, for example, on a 0.1 mF capacitor up to 2.1 V in about 0.56 sec simply by hand tapping. Impressively, the MN-TEG source under tapping can directly light up 53 LEDs with different colors connected in series.