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Page 10 of 12 Jan et al. Soft Sci 2024;4:10 https://dx.doi.org/10.20517/ss.2023.54

CONCLUSIONS
In summary, the LF-TENG, specifically in a dielectric-to-dielectric configuration with PTFE as the tribo-
negative layer and PMMA as the tribo-positive layer, exhibited promising characteristics for pressure
sensing and energy harvesting applications. The working mechanism of LF-TENGs based on the CS mode
was evaluated, demonstrating the generation of a maximum peak-to-peak open-circuit voltage of 52 V
when subjected to mechanical tapping at a low frequency of 4 Hz. Notably, the introduction of an ITO layer
on a Cu electrode deposited on a flexible PDMS substrate improved the electrode quality, resulted in
significantly enhanced voltage output and charge collection efficiency. The LF-TENG with an ITO/Cu
electrode showed a high-power density of 306.2 mW/m . Moreover, the LF-TENG exhibited remarkable
2
pressure sensing capabilities, featuring a sensitivity of 7.287 V/kPa within the lower pressure range (0.0245
to 1.22 kPa) and 0.663 V/kPa in the higher-pressure range (2.45 to 23.3 kPa). This dual-range pressure
sensitivity enables our E-TENG to be highly responsive to a wide spectrum of finger-tapping forces,
rendering it well-suited for tactile and pressure sensing applications. This versatility was extended to human
motion monitoring, where the E-TENG sensor effectively detected wrist and finger movements and even
harnessed energy from everyday physical activities such as walking and jogging. The E-TENG generated the
maximum peak-to-peak voltages of 18.3 and 57.4 V during walking and jogging activities, respectively. With
its high-power density and sensitivity, the E-TENG holds great promise for diverse applications, including
tactile and pressure sensing, healthcare monitoring and rehabilitation, and human-machine interface.

DECLARATIONS
Authors’ contributions
Conceptualization: Jan AA, Kim S (Seok Kim)
Tapping machine Software: Kim S (Seungbeom Kim)
Formal analysis: Jan AA, Kim S (Seungbeom Kim)
Methodology, writing - original draft preparation, writing - review and editing: Jan AA, Kim S (Seungbeom
Kim), Kim S (Seok Kim)

Availability of data and materials
Data is available upon request from the corresponding author.

Financial support and sponsorship
This work was supported by the National Research Foundation of Korea (NRF), funded by the Ministry of
Science and ICT (2022M317A3050820; 2022R1A4A3033320; 2022R1A2C3006420).

Conflicts of interest
All authors declared that there are no conflicts of interest.

Ethical approval and consent to participate
According to the Korea National Institute for Bioethics Policy, under the Human Subject Research Division,
enforcement rule article 13 states that research using only simple contact measuring equipment or
observation equipment that does not cause physical changes is exempt from IRB approval. Our work
involves simply placing the device on the skin, which does not physically affect humans. Therefore, we do
not require IRB approval. All participants participated in the experiment with informed consent.

Consent for publication
Not applicable.

Copyright
© The Author(s) 2024.