The sensitivity of a nanoscale crack-based sensor is enhanced markedly by modulating the crack depth. The crack-depth-propagated sensor exhibits ≈16 000 gauge factor at 2% strain and a superior signal-to-noise ratio of ≈35, which facilitates detection of target signals for voice-pattern recognition.
Owing to the growing demand for highly integrated electronics, anisotropic heat dissipation of thermal management material is a challenging and promising technique. Moreover, to satisfy the needs for advancing flexible and stretchable electronic devices, maintaining high thermal conductivity during the deformation of electronic materials is at issue. Presented here is an effective assembly technique to realize a continuous array of boron nitride (BN) nanosheets on tetrahedral structures, creating 3D thermal paths for anisotropic dissipation integrated with deformable electronics. The tetrahedral structures, with a fancy wavy shaped cross‐section, guarantee flexibility and stretchability, without the degradation of thermal conductivity during the deformation of the composite film. The structured BN layer in the composites induces a high thermal conductivity of 1.15 W m−1 K−1 in the through‐plane and 11.05 W m−1 K−1 in the in‐plane direction at the low BN fraction of 16 wt%, which represent 145% and 83% increases over the randomly mixing method, respectively. Furthermore, this structured BN composite maintains thermal dissipation property with 50% strain of the original length of composite. Various electronic device demonstrations provide exceptional heat dissipation capabilities, including thin film silicon transistor and light‐emitting diode on flexible and stretchable composite, respectively.
Bioelectronics needs to continuously monitor mechanical and electrophysiological signals for patients. However, the signals always include artifacts by patients’ unexpected movement (such as walking and respiration under approximately 30 hertz). The current method to remove them is a signal process that uses a bandpass filter, which may cause signal loss. We present an unconventional bandpass filter material—viscoelastic gelatin-chitosan hydrogel damper, inspired by the viscoelastic cuticular pad in a spider—to remove dynamic mechanical noise artifacts selectively. The hydrogel exhibits frequency-dependent phase transition that results in a rubbery state that damps low-frequency noise and a glassy state that transmits the desired high-frequency signals. It serves as an adaptable passfilter that enables the acquisition of high-quality signals from patients while minimizing signal process for advanced bioelectronics.
Highly sensitive temperature sensors are designed by exploiting the interparticle distance-dependent transport mechanism in nanocrystal (NC) thin films based on a thermal expansion strategy. The effect of ligands on the electronic, thermal, mechanical, and charge transport properties of silver (Ag) NC thin films on thermal expandable substrates of poly(dimethylsiloxane) (PDMS) is investigated. While inorganic ligand-treated Ag NC thin films exhibit a low temperature coefficient of resistance (TCR), organic ligandtreated films exhibit extremely high TCR up to 0.5 K −1 , which is the highest TCR exhibited among nanomaterial-based temperature sensors to the best of the authors' knowledge. Structural and electronic characterizations, as well as finite element method simulation and transport modeling are conducted to determine the origin of this behavior. Finally, an all-solution based fabrication process is established to build Ag NC-based sensors and electrodes on PDMS to demonstrate their suitability as low-cost, high-performance attachable temperature sensors.
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