Auxetic Foam‐Based Contact‐Mode Triboelectric Nanogenerator with Highly Sensitive Self‐Powered Strain Sensing Capabilities to Monitor Human Body Movement

Abstract

The first contact-mode triboelectric self-powered strain sensor using an auxetic polyurethane foam, conductive fabric, and polytetrafluroethylene (PTFE) is fabricated. Utilizing the auxetic properties of the polyurethane foam, the auxetic polyurethane foam would expand into the PTFE when the foam is stretched, causing contact electrification. Due to a larger contact area between the PTFE and the foam as the foam is stretched, this device can serve effectively as a strain sensor. The sensitivity of this method is explored, and this sensor has the highest sensitivity in all triboelectric nanogenerator devices that are used previously as a strain sensor. Different applications of this strain sensor are shown, and this sensor can be used as a human body monitoring system, self-powered scale to measure weight, and a seat belt to measure body movements inside a car seat.

Room-Temperature Self-Repairable Yet Mechanically Robust Elastomeric Triboelectric Nanogenerators Enabled by a Fast-Reversible Dual-Dynamic Network

“…Accordingly, the sensitivity ( S m ) of the device was estimated from the slope, yielding S m values of ∼2.59 nA/mm under stretching and ∼0.27 nA/° under bending. It is worth noting that these sensitivity values exceed those documented in existing literature for available TENGs, which generally fall within a stretching sensitivity range of 0.3–0.4 nA/mm. , In addition, the gentle tapping movements can also be detected with an output current of 29 nA (Figure e). Therefore, the stretchable S-TENG has excellent sensitivity, which is promising for the fabrication of wearable and portable self-powered sensing devices.…”

Stretchable, Transparent, and Self‐Patterned Hydrogel‐Based Pressure Sensor for Human Motions Detection

“…The stretchability of the prepared hydrogel is denoted as strain (=Δ L / L 0 × 100%), where Δ L is the length variation upon tensile force and L 0 is the original length. As shown in Figure b,c, the conductive hydrogel can be stretched up to 400% strain, which is advantageous to many reports . Furthermore, the robust hydrogel can even endure a heavy weight of up to 100 g without obvious shape variation (Figure d).…”

Highly Multifunctional Performances of Boron Nitride Nanosheets/Polydimethylsiloxane Composite Foams

“…For instance, under the compression strain of 10%, when the compression rate was increased from 100 to 500 mm/min, the BSF-9’s output voltage intensities increased from 0.44 to 9.2 V (Figure a). The reason for this upward trend is that the more rapid external mechanical deformation of BSFs induces faster movement frequency of BNNSs-bonding-PDMS media, which triggers higher polarized charge density usable for more transferred charges to generate the gradually higher CDPT voltage values. , Furthermore, keeping deformation speed constant at 500 mm/min, the BSF-9’s voltage response was also enhanced from 8.4 to 19.9 V along with its compressive strain varying from 10 to 50% (Figure b). This strain-evoked CDPT enhancement is primarily ascribed to the increasing friction action between pore networks of the BSF-9 foam with the increasing compression, which provides extra enhanced frictional charges to elevate BSF-9’s final CDPT performance.…”