Multidiscipline Applications of Triboelectric Nanogenerators for the Intelligent Era of Internet of Things

Abstract

In the era of 5G and the Internet of things (IoTs), various human-computer interaction systems based on the integration of triboelectric nanogenerators (TENGs) and IoTs technologies demonstrate the feasibility of sustainable and self-powered functional systems. The rapid development of intelligent applications of IoTs based on TENGs mainly relies on supplying the harvested mechanical energy from surroundings and implementing active sensing, which have greatly changed the way of human production and daily life. This review mainly introduced the TENG applications in multidiscipline scenarios of IoTs, including smart agriculture, smart industry, smart city, emergency monitoring, and machine learning-assisted artificial intelligence applications. The challenges and future research directions of TENG toward IoTs have also been proposed. The extensive developments and applications of TENG will push forward the IoTs into an energy autonomy fashion.

Keywords: Artificial intelligence; Internet of things; Machine learning; Self-powered sensor; Triboelectric nanogenerator.

Fig. 1

a A comparison of the Maxwell’s equations for stationary media and moving charged media [42]. b The basic operation modes and two main applications of triboelectric nanogenerators. i Contact-separation mode. ii Lateral-sliding mode. iii Freestanding mode. iv Single-electrode mode

Fig. 2

Multi-discipline applications of triboelectric nanogenerators for the intelligent era of Internet of things [29, 46, 68, 75, 80, 82, 129, 149, 150, 187]

Fig. 3

Application of triboelectric nanogenerators in smart agriculture. a Three essential elements of smart agriculture, the illustration of the BD-TENG structure, and application scenario of collecting natural breeze energy to power soil thermometer [62]. Copyright 2021 Elsevier Ltd. b Schematic diagram of the proposed SCR-TENG in the smart farm, the detailed structure, and electrical performance of the TENG [68]. Copyright 2021 Wiley–VCH GmbH. c System architecture of the self-powered wireless smart-farm monitoring (SWSFM) system powered by the CMTUr-HNG and the schematic diagram of ultra-robust hybrid nanogenerator (CMTUr-HNG) triggered based on non-contact mode [75]. Copyright 2021 Elsevier Ltd

Fig. 4

TENG applications in smart industry. a Schematic of the proposed heat recovery system, structure of the LDT Stirling engine, the disk TENG, and the EMG [80]. Copyright 2021 Elsevier Ltd. b Schematic diagram of TENG tilt sensor applied to ship attitude sensing and experimental apparatus, and circuit diagrams and design of the self-powered system [81]. Copyright 2021 American Chemical Society. c Application of the smart chemical protective suit in biological movement energy harvesting and self-powered safety monitoring system [82]. Copyright 2021 Wiley–VCH GmbH. d Schematic diagram of seawater self-powered electrolysis and TENG test system [87]. Copyright 2021 Published by Elsevier Ltd

Fig. 5

TENG applications in smart industry: speed sensing. a Schematic diagram of drill pipe sensor structure and testing devices [89]. Copyright 2021 Elsevier B.V. b 3D structure diagram of the self-powered sensor and actual use of impeller input for detecting low-speed and high-speed wind [92]. Copyright 2021 Elsevier Ltd. c Modification of the gear surface by continuous coating of conductive and dielectric materials, configuration of gear box operation condition monitoring system [93]. Copyright 2020 Elsevier Ltd

Fig. 6

TENG applications in smart industry: roller bearings. a Schematic diagram of the principle and working mechanism of TENG-type ball bearing with semisolid lubricant [100]. Copyright 2021 Elsevier Ltd. b Structural decomposition diagram of NC-TEBS and real-time sensor monitoring and testing system using NC-TEBS [105]. Copyright 2021 Elsevier Ltd. c Structure diagram and working mechanism of rolling-independent mode TENG (RF-TENG); linear discriminant analysis (LDA) is used to extract features and reduce dimensions of the raw data [106]. Copyright 2021 Elsevier Ltd

Fig. 7

TENG applications in smart home. a Schematic illustration of household mechanical energy, energy storage, and their applications [46]. Copyright 2020 Elsevier Ltd. b Application of W-TENG in smart home, and the schematic diagrams of W-TENG [110]. Copyright 2020 Elsevier Ltd. c Practical smart home applications of all wood-based TENG [147]. Copyright 2021 Elsevier Inc. d Illustration of the password authentication access control system. A password is required to enter the door and access control system [47]. Copyright 2020 Elsevier Ltd

Fig. 8

TENG applications in smart transportation: driver behavior monitoring. a Schematic illustration of self-powered triboelectric sensors for driver behavior monitoring and voltage signal acquisition [124]. Copyright 2018 Elsevier Ltd. b Schematic illustration of fatigue test and electrical signals of different actions (eyes closed, mouth open, nodding, and neck twisting) [125]. Copyright 2020 Elsevier Ltd. c Position diagram of the AS-TENG sensor arrays on the safety belt for monitoring the driver’s steering actions, and the structures of the APU-TENG and AS-TENG [126]. Copyright 2019 Elsevier Ltd

Fig. 9

TENG applications in smart transportation: condition monitoring. a Working principle of self-powered vehicle monitoring system fixed on the main axis of automatic vehicles and BS-TENG rolling independent mode [129]. Copyright 2021 The Author(s). Published by Elsevier Ltd. b Schematic illustration of the TM-based portable scanner for book ISBN recognition by slow gesture recognition, and the TM-based scanning system for moving obstacle detection by low-speed tire rolling [50]. Copyright 2019, The Author(s), published by Springer Nature. c Schematic diagram of the self-powered hydrogen leakage sensing system, structure and working principle of WL-TENG, and equivalent circuit with divider resistor of the self-powered H₂ sensor monitor system [49]. Copyright 2021 Elsevier Ltd. d Functional demonstrations of speed limit adjustment, vehicle overlapping detection, and speeding capture for the traffic management system realized by the CN-STS and real-time charge density output signals through Raspberry Pi [134]. Copyright 2021 Elsevier Ltd

Fig. 10

TENG applications in smart transportation: railway monitoring. a Structure design and output power of elastic rotation TENG [136]. Copyright 2021 American Chemical Society. b Multiple-mode TENG with charge excitation collects environmental mechanical energy for self-powered freight train monitoring [137]. Copyright 2021 Elsevier Ltd. c Self-powered wireless smart sensor based on magnetic levitation porous nanogenerator for a train monitoring system [138]. Copyright 2017 Elsevier Ltd

Fig. 11

TENG applications in smart transportation: navigation monitoring. a Schematic of hybrid wave energy harvesting nanogenerator (HW-NG) network distributed in the waters adjacent to coral reefs, which is used to harvest wave energy, and the developed automatic RAW system for ocean navigation [141]. Copyright 2021 Wiley–VCH GmbH. b Schematic diagram of TENG tilt sensor applied to ship attitude sensing and experimental apparatus [143]. Copyright 2020 Elsevier B.V. c Schematic and experimental structure of a fully self-powered vibration monitoring sensor driven by AC/DC-TENG [145]. Copyright 2020 American Chemical Society. d Schematic diagram of the sensor working in the tunnel, and the enlarged view of the self-power sensing system [146]. Copyright 2016 American Chemical Society

Fig. 12

TENG applications in emergency monitoring and early warning. a Schematic illustration of the MC-TENG and self-powered fire alarm system for harvesting shaking kinetic energy of tree branches [148] Copyright 2020 WILEY–VCH Verlag GmbH & Co. KGaA, Weinheim. b Application prospect of the F-TENG in self-powered intelligent fire protection systems [149]. Copyright 2021 Wiley–VCH GmbH. c Application scene and the circuit schematic diagram of the self-powered wildfire pre-warning system [150]. Copyright 2021 Elsevier Ltd. d Prospect chart of an outdoor positioning device based on SCPS, voltage curves of the SCPS during the GPS charging and power supply. Schematic diagrams of the location information sent by the outdoor positioning device [151]. Copyright 2021 Elsevier Ltd

Fig. 13

AI applications of TENG with machine learning. a Combining leaf-inspired TENG and machine learning method, the process of handwriting recognition is demonstrated [37]. Copyright 2020 Elsevier Ltd. b Scanning process based on the CR-TENG and the flowchart of the character recognition process of the system [174]. Copyright 2020 Elsevier Ltd. c Design of biometric tactile system based on fingerprint-sensing electronic skin (FE-skin) and artificial neural network [29]. Copyright 2021 Elsevier Ltd

Fig. 14

AI applications of TENG with machine learning. a Schematic and exploded view of a single triboelectric key. The system overview includes the training process and the authentication/identification process, and the difference matrix between user inputs of different feature types combinations [177]. Copyright 2018 Elsevier Ltd. b Experimental platform and the framework of the proposed method [171]. Copyright 2020 Elsevier Ltd. c Artificial intelligence toilet (AI-Toilet) for integrated health monitoring system and t-SNE diagram of sitting posture dataset recorded from the pressure sensor array [178]. Copyright 2021 Elsevier Ltd

Fig. 15

AI applications of TENG with machine learning. a Process from sensory information collection to the real-time prediction in VR fitness games and the confusion map of deep learning results [32]. Copyright 2020, Copyright The Author(s), Published by Springer Nature. b Demonstration of shooting game, which is based on the amplitude of output signals. And the AR demonstration of flower arrangement based on machine learning for complex gesture recognition [48]. Copyright 2020 The Authors. Published by WILEY–VCH Verlag GmbH & Co. KGaA, Weinheim

Fig. 16

AI application of TENG with digital twin technology. a Smart floor monitoring system based on the deep learning-enabled smart mats (DLES-mats) [186]. Copyright 2020, The Author(s), Published by Springer Nature. b Schematic of the low-cost TENG for soft gripper and its digital twin applications. The process flows from sensory information collection to ML training and real-time prediction in digital twin system [33]. Copyright 2020, The Author(s), Published by Springer Nature. c System architecture of the digital-twin-based virtual shop and ML-enabled automatic grasped objects recognition system [187]. 2021 Copyright The Authors. Advanced Science published by Wiley–VCH GmbH

Fig. 17

Challenges and perspectives of the IoTs application based on TENG sensors