Sep 06, 2013 |
Skin-based nanogenerators harvest biomechanical energy
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(Nanowerk News) A research team from Georgia Institute of Technology, Chongqing University and Beijing Institute of Nanoenergy and Nanosystems have demonstrated a human skin-based triboelectric nanogenerators (TENG), consisting of a skin patch, a PDMS film with a micropyramid-structured surface, and an ITO electrode connected with a ground across an external load ("Human Skin Based Triboelectric Nanogenerators for Harvesting Biomechanical Energy and as Self-Powered Active Tactile Sensor System").
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The mechanism of TENG is based on the charge transfer between the ITO electrode and the ground by utilizing the contact/separation between the skin patch and the PDMS film.
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Left: Photograph of the fabricated PDMS film on the ITO electrode. Upper right: The total charges on the ITO electrode as a function of the separation distance between the skin and PDMS film. The increase in total charges is a result of the electron flow from ITO to the ground. Lower right: Measured positive output voltage mapping figure. (© ACS)
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By converting the biomechanical energy into electricity, the TENG produces an open-circuit voltage up to 1000 V, a short-circuit current density of 8 mA/m2, and a power density of 500 mW/m2 on a load resistance of 100MΩ, which can be used to directly light up tens of green LEDs. Moreover, the fabricated TENGs have been used to design an independently addressable matrix for monitoring the localized touching actions of human skin.
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The matrix exhibits both transparent and flexible characteristics, where each pixel can have a size of 3 mm x 3 mm. The tactile information including the position and pressure can be determined by analysis of the realtime recording of positive output voltage signals in the matrix as a mapping figure.
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The detection sensitivity of the pressure is about 0.29 ± 0.02 V/kPa. The size of each sensor unit can be significantly reduced so that the spatial resolution can be largely improved.
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This work pushes forward a significant step toward the practical applications of skin-based biomechanical energy harvesting techniques and self-powered touchpad technology.
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