-We present a piezoelectric energy harvester with stopper-engaged dynamic magnifier which is capable of significantly increasing the operating bandwidth and the energy (power) harvested from a broad range of low frequency vibrations (<30 Hz). It uses a mass-loaded polymer beam (primary spring-mass system) that works as a dynamic magnifier for another mass-loaded piezoelectric beam (secondary spring-mass system) clamped on primary mass, constituting a two-degree-of-freedom (2-DOF) system. Use of polymer (polycarbonate) as the primary beam allows the harvester not only to respond to low frequency vibrations but also generates high impulsive force while the primary mass engages the base stopper. Upon excitation, the dynamic magnifier causes mechanical impact on the base stopper and transfers a secondary shock (in the form of impulsive force) to the energy harvesting element resulting in an increased strain in it and triggers nonlinear frequency up-conversion mechanism. Therefore, it generates almost four times larger average power and exhibits over 250% wider half-power bandwidth than those of its conventional 2-DOF counterpart (without stopper). Experimental results indicate that the proposed device is highly applicable to vibration energy harvesting in automobiles.

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This work reports a novel flexible triboelectric nanogenerator (TENG) based on the conductive nylon membrane (NM). Multiwall carbon nanotubes were directly composited with the poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) solution and deposited on one side of the NM surface through vacuum filtration method. The sheet resistance of the fabricated composite material was found as 24 Ω/square and the charged output voltage of 10 µF capacitor was 7.9 V. The NM-based TENG showed robust output power when NM contacted with friction layer of polytetrafluoroethylene (PTFE). The friction layer was consisted of adhesive conductive fabric attached with PTFE. Due to its well flexibility, simple process of fabrication and high output performance, the generator has much potential for powering up portable electronics.

Recent advances in supercapacitive pressure sensors based on iontronic film have a significant capacitive response and a low detection limit due to their large capacitance change resulting from electrical double layer (EDL) and these pressure sensors are used to detect a wide range of pressure with high resolution for various applications such as prosthesis, wearable devices, and robotics. Thus, the enhancements to the EDL capacitive response are significantly important challenges for advanced applications with outstanding performances. Herein, an ultra‐sensitive and quick‐responsive hybrid‐supercapacitive iontronic pressure sensor using a novel sensing mechanism and facile fabrication technique is reported to overcome the limitations of the existing iontronic pressure sensors. As a sensing material, conductive polymer and carbon nanotube are incorporated into the iontronic film, as pseudo‐ and EDL‐capacitive material, respectively. Moreover, vinyl silica nanoparticle (VSNP) is used to decrease the recovery time by making the iontronic film quick‐response. The developed hybrid‐supercapacitive pressure sensor exhibited an ultra‐high sensitivity of 301.5 kPa−1 over a wide pressure range of up to 63.3 kPa along with a fast recovery time of ≈32 ms. It is believed that the proposed hybrid‐supercapacitive mechanism in iontronic film will significantly enhance the performance of conventional iontronic pressure sensors.