A commonly used configuration of TENGs is a free-standing mode with 6 electrolytes which gives a power output of 14.84mW. This setup is preferable for powering small-scale electronic devices and is very useful in IoT applications. Triboelectric nanogenerators operate on the principle of triboelectricity. It works on the principle of frictional sliding, triboelectric charges are generated on the surfaces between the two dielectrics, causing a potential difference between the two electrodes.

The simplicity of the mechanism allows the use of TENGs in various power harvesting sources such as human movement, vibrations, wind, and water flow. After a lot of research, the average power density of TENGs was calculated to be raised to 87.26 W m−2 Hz−1, which is sufficient to meet the power requirements of most electronic devices in IoTs, making it a potential game-changer for small-scale, renewable energy generation.

Figure 1: Use of TENG as power harvesters

Due to its usage on a large scale, there is always a demand for increasing the efficiency of performance. Researchers have developed various effective strategies, including charge excitation local discharge, space charge accumulation, charge migration, etc., to boost the output performance of TENGs. However, it possesses several limitations but the major problem that affects the performance of TENG is its high intrinsic impedance this leads to a mismatch of output energy from TENG to the input energy required by the applications they are powering.

Solution to Irregular Power Supply

TENGs provide irregular power output because they generate energy from unstable mechanical energy sources. These irregular inputs occur because TENGs take energy from mechanical sources which can be highly irregular some TENGs use water flow or wind flow, but the flow is highly irregular as it depends upon a lot of other natural factors.

In real-world applications, these energy sources rarely provide a constant, smooth mechanical input, instead, they come in bursts or fluctuating cycles, creating inconsistent power output from the TENG. This irregularity poses challenges for directly powering devices, as most electronics require stable, continuous energy to function effectively. To overcome this problem, integration of TENGs with an energy management circuit, helps with the output regulations and comes with an energy storage system. When the power consumption of a device is lower than the input power from the TENG, the output terminal can maintain a constant voltage, allowing for consistent load operation. Excess energy is stored in the input capacitor (Cin) for future use, which is crucial for applications where the mechanical energy harvested may be intermittent.

The energy storage system enables continuous power output even when the mechanical energy input is unstable. It was also found that using this mechanism a rotating TENG that only works for 21s can make a hygrothermograph run for 417s which is significantly higher than normally used TENGs. Also, hand-driven TENG which have irregular inputs can be used to run small systems such as mini game consoles and calculators using these EM circuits. Even though theoretically the power efficiency seemed to increase in practical use the power efficiency increased only by 5%.

Overcoming the Limitations by Resolving the Topologies in TENGs

To tackle the limitations of TENG, the need for optimization so synergistic optimization was suggested for both the TENG itself and the energy management circuit. Here the main focus was to reduce the charge loss and voltage loss caused by the switches used in the TENGs for controlling the energy flow. By optimizing the TENG’s switching configuration the current and voltage losses are significantly reduced. This increased the conversion efficiency by 42.5% which is 8.5 times higher than the EM circuits.

The power losses can be further minimized by designing an efficient energy management circuit. Zener diode is generally used to stabilize the voltage, but this approach affects the energy loss when the power exceeds the required power level because the diode dissipates the extra energy as heat, which reduces the overall efficiency of the TENG system. Recognizing this issue the researchers came up with a special chip LTC-3588-1 which is essential for regulating voltage and could be a potential solution. The direct integration of the chip with TENGs initially showed low energy utilization rates, largely due to inefficiencies in the energy transfer process between the TENG and the input capacitor which is the basic energy storage component. To tackle this problem, chip was integrated with the TENG system to optimize the performance. 3588 is a newer version of the chip which can maintain stable output voltage when the load resistance exceeds 60 kΩ, with an output power of 56.8 μW. By applying the EM strategy, the system improves energy conversion efficiency by 121.5 times, reaching an RMS output power of 6.9 mW under a 500 Ω load.

Figure 2

The improved efficiency of TENGs makes them more usable across different applications such as for real-time applications where we need to replace batteries which is both costly and inconvenient. Optimized TENGs can be used in environmental monitoring, smart cities, and portable electronics where there is abundant mechanical energy. By continuing to optimize TENG configurations and integrating more advanced energy management circuits, researchers believe that the energy utilization efficiency of TENGs can be further enhanced, making them a core component in the future of sustainable energy solutions.