| Triboelectrification, almost existing everywhere and anytime, is a commen and immemorial effect which is known to each scientific researcher and even to everyone probably since ancient Greek time, but it is usually considered as a negative effect and is avoided in many cases with some technologies. Triboelectric nanogenerator (TENG) has recently been invented by Dr. Zhong Lin Wang’s group at Georgia Institue of Technology that is utilized to convert mechanical energy into electricity based on triboelectrification coupled with electrostatic induction. As for this power generation unit, in the inner circuit, a potential is produced by the triboelectric effect due to the charge transfer between two thin triboelectric layers that exhibit different tribo-polarity; in the outer circuit, electrons are driven to flow between two electrodes attached on the back sides of the triboelectric layers or between electrode and ground in order to balance the potential. It is critical and essentially necessary to develop the TENG extensively because TENG technology is a promising energy harvesting approach which can be used not only in large-scale energy scavenging, but also in tiny-scale energy harvesting. It is possible to address worldwide energy shortage and to promote personal electronics and self-powered systems by TENG. In this paper, we designed several TENGs with different structures, different working principles and different applications. Through systematic experiments and theoretical simulation, we got a further understanding of TENG’s operation mechanism and extended the potential applications widely. I believe that TENG will change our routine life in the near future.The details of this research are described as fellows:①Methyl orange (MO), as a typical dye in textile waste water, generally can be degraded through an electrocatalytic oxidation process driven by a power source due to the superoxidative hydroxyl radical generated on the anode. Here, we demonstrate a hybrid energy cell that can be utilized for a self-powered electrocatalytic reaction for the degradation of MO without using any external power source. The designed hybrid energy cell is capable of simultaneously or individually harvesting mechanical and thermal energies. The mechanical energy was scavenged by the triboelectric nanogenerator (TENG) fabricated at the top by using a flexible polydimethysiloxane (PDMS) nanowire array with diameters of about200nm. A pyroelectric nanogenerator (PENG) was constructed below the TENG to harvest thermal energy. The hybrid energy cell was systematically electronically characterized to achieve a high output performance. It has been proved that the power output of the hybrid device can be directly used for electrodegradation of MO, indicating a successful self-powered electrocatalytic oxidation process. The self-powered electrocatalytic degradation can be applied in other environmental monitoring or improvement.②A spherical three-dimensional triboelectric nanogenerator (3D-TENG) with a single electrode is invented. The3D-TENG consists of an outer transparent shell and an inner polyfluoroalkoxy (PFA) ball. Based upon the conjunction of triboelectrification and electrostatic induction, the rationally constructed3D-TENG can effectively harvest ambient vibration energy in full space and convert into electricity by operating at a hybridization of both the contact-separation mode and the sliding mode, leading the electron transfer from the Al electrode to the ground or from the ground to the Al electrode. By systematically investigating the output performance of the device vibrating under different frequencies and along different directions, the TENG can achieve a maximal output voltage of57V and a maximal output current of2.3μA with a corresponding output power of128μW on a load of100MQ, which can be utilized to directly drive tens of green light-emitting diodes. Furthermore, the TENG is used to design the self-powered acceleration sensor with detection sensitivity of15.56V/g. This study opens up a new world of potential applications of TENGs based on single electrode for ambient vibration energy harvesting techniques in full space and the self-powered vibration sensor systems.③Triboelectric nanogenerators (TENG) based on human skin is reported here that can either harvest biomechanical energy or be utilized as a self-powered tactile sensor system for touch pad technology. We invented a TENG utilizing the contact/separation between an area of human skin and a polydimethylsiloxane (PDMS) film with a surface modified with micropyramid structures, which was attached on an ITO electrode that was grounded across a loading resistor. The designed TENG delivers an open circuit voltage up to1000V, a short-circuit current density of8mA/m2, and a power density of500mW/m2on a load of100MQ, which can be employed to directly light up tens of green light-emitting diodes. The working principle of the TENG is based on the charge transfer between the ITO electrode and ground via modulating the separation distance between the tribo-charged skin patch and PDMS film. Moreover, the TENG has been used in designing an independently addressed matrix for tracking the location and pressure of human touch. The fabricated matrix has demonstrated its self-powered and high-resolution tactile sensing capabilities by recording the output voltage signals as a mapping figure, where the detection sensitivity of the pressure is about0.29±0.02V/kPa and each pixel can have a size of3mm X3mm. The TENGs may have potential applications in human machine interfacing, micro/nano-electromechanical systems, and touch pad technology.④Rotational energy is abundant and widely available in our living environment. Harvesting ambient rotational energy has attracted great attention. In this work, we report a single-electrode-based rotating triboelectric nanogenerator (SR-TENG) for converting rotational energy into electric energy. The unique advantage of introducing the single-electrode TENG is to overcome the difficulty in making the connection in harvesting rotational energy such as from a moving and rotating tire/wheel. The fabricated device consists of a rotary acrylic disc with polytetrafluoroethylene (PTFE) blades and an Al electrode fixed on the base. The systematical experiments and theoretical simulations indicate that the asymmetric SR-TENGs exhibit much better output performances than those of the symmetric TENGs at the same rotation rates. The asymmetric SR-TENG with seven PTFE units at the rotation rate of800r/min can deliver a maximal output voltage of55V and a corresponding output power of30μW on a load of100MQ, which can directly light up tens of red light-emitting diodes. The SR-TENG has been utilized to harvest mechanical energy from rotational motion of a bicycle wheel. Furthermore, we demonstrated that the SR-TENG can be applied to scavenge wind energy and as a self-powered wind speed sensor with a sensitivity of about0.83V/(m/s). This study further expands the operation principle of a single-electrode-based TENG and many potential applications of TENGs for scavenging ambient rotational energy and as a self-powered environment monitoring sensor.⑤A triboelectric nanogenerator (TENG) based on the contact-separation mode between a patterned polydimethylsiloxane (PDMS) film and an Al foil was fabricated between clothes for harvesting body motion energy. Under the generally walking, the maximum output of voltage and current density are up to17V and0.02μA/cm2, respectively. The TENG with a single layer size of2cm X7cm X0.08cm sticking on the clothes was demonstrated as a sustainable power source that not only can directly light up30light-emitting diodes (LEDs), but also can charge a lithium ion battery by persistently clapping clothes. The electric energy stored in the lithium ion battery was used to power a biosensor for detecting glucose. The detection of bioactive chemicals in our body using the energy harvested from body motion is demonstrated. Moreover, due to the sensitivity and desirable stability to periodic vibration, the TENG was used to measure stride frequency as well. |
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