Abstract
A rapid development in personal electronics has raised challenging requirements for portable and sustainable power sources. For example, in wearable technologies, the concept of wearable body area network brings body motion and vital signs monitoring together in synergy. For this, a key aspect is sustainable portable energy, available anywhere, at any time, as generated by triboelectric nanogenerators (TENG). This technology usually demands high-cost processes and materials and still suffer from low power output, as well as unstable output values due to charge generating stimulus with variable intensities. In this work, we present TENGs using shear exfoliated graphene as electrodes as well as active triboelectric layer deposited by a simple solution process. Graphene in combination with polymers such as polydimethylsiloxane (PDMS) were used to produce TENG devices using low-cost solution processing methods. Device electrical power generation was tested with a cyclic physical stimulus for better control and understanding of device output. The triboelectric response of these materials showed open circuit voltages (Voc) and short-circuit currents (Isc)of approximately 233 V and 731 nA respectively when stimulated at 1.5 Hz. A power density of 13.14 μW/cm2 under a load of 200 MΩ was achieved, which can be 40 times higher when compared to devices made with aluminum and PDMS. These results demonstrate the potential of solution process for low-cost triboelectric devices for self-sustainable wearable portable nanogenerators on health and security applications using contact and positional sensors.
Highlights
Among sustainable energy-harvesting sources [1], mechanical energy is one of the most versatile and commonly available, capable to contribute to milliwatts and sometimes even few watts of energy produced by human body motion [2, 3]
The individual components for these two devices and their assembly are schematized in Figure 1, and, as shown, both used a PDMS negative triboelectric layer deposited through a solution process with an Shear-exfoliated graphene (SEG) back electrode
With this work we demonstrated an easy, low-cost and fast process to fabricate a triboelectric nanogenerators (TENG) based on the triboelectric effect of PDMS with shear exfoliated graphene
Summary
Among sustainable energy-harvesting sources [1], mechanical energy is one of the most versatile and commonly available, capable to contribute to milliwatts and sometimes even few watts of energy produced by human body motion [2, 3] This energy, if efficiently harvested through triboelectric nanogenerators (TENG), could be sufficient for autonomous operation of small IoT, wearable or medical devices, sensors and actuators [2,3,4,5]. All graphene layers were developed using shear exfoliated graphene and transferred using vacuum filtration techniques to integrate easy and low-cost solution-based methods This device takes advantage of the triboelectric effect between PDMS and graphene and was developed with an extra polymeric layer to prevent current leakage from the PDMS layer to its back electrode. The output power behaviour associated with the external load connected to the TENG is similar to a device fabricated using a standard PDMS and aluminum triboelectric pair
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