A Fully Verified Theoretical Analysis of Contact‐Mode Triboelectric Nanogenerators as a Wearable Power Source

Abstract

cost, environmental friendliness, and universal availability. [6][7][8][9][10][11][12][13][14][15][16][17][18] To improve the performance and broaden the applications of TENGs, numerous efforts have been made with focus on both enhancement of the surface charge density and development of new structures/modes. [ 2,4,7,9,13,[19][20][21][22][23][24][25] So far, the electric power output of TENGs has been improved up to ≈500 W m −2 by sophisticated design of device structure. [ 18,[26][27][28] Demonstrated TENGs have been working in four modes, that is, the contact-separation or contact mode in short, sliding mode, single-electrode mode, and free-standing triboelectric-layer mode. The performance of the TENGs in contact-mode is better than that of TENGs in the sliding mode, because a much higher maximum displacement of TENGs in the sliding mode is required than that of TENGs working in the contact-mode, in order to achieve the same level of open circuit voltage. [ 29 ] The TENGs working in the contact-mode are particularly interesting for applications like foot-mounted wearable electronic systems because of the short vertical displacement involved and ease of integration.The fundamental principle of TENGs is based on the coupled effects of triboelectrifi cation and electrostatic induction. A theoretical model has been proposed for the TENGs working in the contact mode by Wang and co-workers. By utilizing the derived governing equation, the real-time output characteristics and the relationship between the optimum external resistance and TENG para meters were numerically simulated. [ 30 ] However, the model was not validated by corresponding experiments with measured real-time output characteristics. Furthermore, it is known that the real-time output characteristics would be affected by the materials, device structural parameters, operation conditions, and equivalent resistance. Assumptions made on simple profi les of working velocity may infl uence the model's validity in real situations. For instance, during real human walking, the previous wearing trials of an intelligent footwear system illustrated that the velocity profi le was complex and varied signifi cantly with time for a foot-mounted device. [ 31,32 ] Therefore, it is highly desirable to develop a theoretical model that is fully verifi ed by corresponding experiments. Such an experimentally verifi ed model is essential for designing and optimizing TENGs for intended applications.In this paper, based on conservation of charges and zerovoltage for close-loop circuits, a theoretical model is presented Harvesting mechanical energy from human activities by triboelectric nanogenerators (TENGs) is an effective approach for sustainable, maintenance-free, and green power source for wireless, portable, and wearable electronics. A theoretical model for contact-mode triboelectric nanogenerators based on the principles of charge conservation and zero loop-voltage is illustrated. Explicit expressions for the output current, voltage, and power are presented for the TENGs ...

Nonlinear dynamics and triboelectric energy harvesting from a three-degree-of-freedom vibro-impact oscillator

“…Moreover, the results of this study agree with those in Ref. [55] in the sense that both studies conclude that higher impact or contact velocity corresponds to higher electrical output. See Sect.…”

“…It is again noted that a higher impact or contact velocity induces a higher electrical output agrees with the conclusion drawn in Ref. [55].…”

“…(9) in Ref. [55], the latter of which has been validated by experiment [55], providing a degree of confidence in the present modelling approach. Moreover, the results of this study agree with those in Ref.…”

An Adhesive Surface Enables High‐Performance Mechanical Energy Harvesting with Unique Frequency‐Insensitive and Pressure‐Enhanced Output Characteristics

“…The operational principle of VPAGs is like that of the reported triboelectric nanogenerators (TENGs) based on CE between nonadhesive surfaces. [2,[6][7][8][9][19][20][21][22][23] When an external load is connected between two electrodes (or shorted), free electrons will be driven to flow back and forth to build an opposite potential to balance the dynamic electrostatic field caused by the separation and contact processes of the electrified surfaces ( Figure S1, Supporting Information). These processes lead to the formation of alternating electric signals.…”

“…These results are consistent with the dependence of the output performance of TENGs on the triggering frequency reported based on the conventional strategy of using different nonadhesive triboelectric materials. [ 2,20–23 ] For comparison, we also used the nonadhesive CNF surface to replace the adhesive surface for a nonadhesive surface‐based TENG. Its positive and negative peak voltages both showed typically linear decreasing trends with impact frequency under different impact forces (Figure S2, Supporting Information).…”