ABSTRACT
Triboelectric nanogeneration is a burgeoning and promising technology for harvesting low-frequency mechanical energy from the environment, but the energy conversion efficiency and service life of the triboelectric nanogenerator (TENG) device are limited by the inevitable frictional resistance between the tribo-surfaces. Herein, we propose an electrostatic induction nanogenerator (EING) circulation network (EICN) by integrating an arbitrary number of EING units for harvesting low-frequency mechanical energy. Because of absolute conquering of the friction resistance between the tribo-surfaces, the average power density of the EING device in the EICN by the initial charge injection (from a TENG or a power supply) is more than a 15-fold enhancement compared with the previous swing-structured TENG. The EICN can recover to the stable and optimal electrical output state in 90 s without external charge injection, even if the external triggering interrupts for 40 min and then restarts, demonstrating the excellent application feasibility of this strategy. To display the practical application scenario for harvesting large-scale mechanical energy from the environment, a high-performance and ultralow-friction TENG is designed for the initial charge injection to the EICN. Moreover, portable electronic devices are powered successfully to realize the self-powered sensing and remote marine environmental monitoring when an EICN with three EINGs is triggered by the real water wave. This EICN strategy not only can harvest low-frequency swing type mechanical energy but also has the capacity of harvesting the rotational mechanical energy after reasonable structure modification, providing an excellent candidate for large-scale blue energy harvesting in practical applications.
ABSTRACT
Microfluidic technology, as a method for manipulating tiny fluids, has the advantages of low sample consumption, fast reaction, and no cross-contamination. In a microfluidic system, accurate manipulation of droplets is a crucial technology that has been widely investigated. In this work, a self-powered droplet manipulation system (SDMS) is proposed to realize various droplet operations, including moving, splitting, merging, mixing, transporting chemicals and reacting. The SDMS is mainly composed of a triboelectric nanogenerator (TENG), an electric brush, and a microfluidic device. The TENG serves as a high-voltage source to power the system. Using different electric brushes and microfluidic devices, different manipulations of droplets can be achieved. Moreover, by experiments and simulations, the influence of the electrode width, the electrode gap and the central angle of one electrode on the performance of SDMS is analyzed in detail. Firstly, by using electrowetting-on-dielectric (EWOD) technology, SDMS can accurately control droplets for long-distance linear movement and simultaneously control multiple droplets to move in a circular electrode track consisting of 40 electrodes. SDMS can also manipulate two droplets of different components to merge and react. In addition, using dielectrophoresis (DEP) technology, SDMS can separate droplets with maximum volumes of 400 µL and reduce the time of the complete mixing of two droplets with different components by 6.3 times compared with the passive mixing method. Finally, the demonstration shows that a droplet can be manipulated by hand power for chemical delivery and chemical reactions on a circular electrode track without an external power source, which proves the applicability of SDMS as an open-surface microfluidic device. Therefore, the self-powered droplet manipulation system proposed in this work may have great application in the fields of drug delivery, micro chemical reactions, and biological microanalysis.
