Throat cancer treatment involves surgical removal of the tumor, leaving patients with facial disfigurement as well as temporary or permanent loss of voice. Surface electromyography (sEMG) generated from the jaw contains lots of voice information. However, it is difficult to record because of not only the weakness of the signals but also the steep skin curvature. This paper demonstrates the design of an imperceptible, flexible epidermal sEMG tattoo-like patch with the thickness of less than 10 μm and peeling strength of larger than 1 N cm −1 that exhibits large adhesiveness to complex biological surfaces and is thus capable of sEMG recording for silent speech recognition. When a tester speaks silently, the patch shows excellent performance in recording the sEMG signals from three muscle channels and recognizing those frequently used instructions with high accuracy by using the wavelet decomposition and pattern recognization. The average accuracy of action instructions can reach up to 89.04%, and the average accuracy of emotion instructions is as high as 92.33%. To demonstrate the functionality of tattoo-like patches as a new human-machine interface (HMI) for patients with loss of voice, the intelligent silent speech recognition, voice synthesis, and virtual interaction have been implemented, which are of great importance in helping these patients communicate with people and make life more enjoyable.
There is an abundance of low-frequency and irregular human motion energy that can be harvested. In this work, a non-resonant rotational electromagnetic energy harvester (REH) for scavenging low-frequency (<10 Hz) and irregular human motion is presented. The energy harvester simply introduces a cylindrical stator and a disk-shaped rotor forming a movement of a higher pair. Without any complicated transmission mechanism, the rotor can easily rotate around the stator by magnetic attractive force. Driven by a broadband frequency vibration, the magnetic rotor is coupled with surrounding wound coils to operate electromagnetic energy harvesting. Theoretical and experimental investigations of the REH are studied, and numerical simulations show good agreement with the experimental results. The treadmill tests at various motion speeds are performed to demonstrate the advantage of the REH in harvesting energy from irregular human motion. At a driving frequency of 8 Hz, the electromagnetic coils can provide the maximum power of 10.4 mW at a load resistance of 100 Ω. The REH exhibits outstanding output performance and has potential applications for powering intelligent wearable or portable electronic devices.
This paper proposes an impact-based micro piezoelectric energy harvesting system (PEHS) working with the frequency up-conversion mechanism. The PEHS consists of a high-frequency straight piezoelectric cantilever (SPC), a low-frequency S-shaped stainless-steel cantilever (SSC), and supporting frames. During the vibration, the frequency up-conversion behavior is realized through the impact between the bottom low-frequency cantilever and the top high-frequency cantilever. The SPC used in the system is fabricated using a new micro electromechanical system (MEMS) fabrication process for a piezoelectric thick film on silicon substrate. The output performances of the single SPC and the PEHS under different excitation accelerations are tested. In the experiment, the normalized power density of the PEHS is 0.216 μW·g−1·Hz−1·cm−3 at 0.3 g acceleration, which is 34 times higher than that of the SPC at the same acceleration level of 0.3 g. The PEHS can improve the output power under the low frequency and low acceleration scenario.
Ocean wave is one of the promising renewable energy sources all around the world. In this paper, an electromagnetic ocean wave energy harvester (OWEH) based on efficient swing body mechanism is presented. A swing body senses the ultra-low frequency wave motion and drive the rotor of an electromagnetic power module (EPM) rotating at high speed through transmission gears. A series of electromagnetic and dynamic simulations were carried out to optimize the power generation capability of the OWEH. Additionally, the power management circuit is specially designed such that the generated power is able to charge a lithium battery and discharge an external load automatically. The OWEH is installed inside an ocean buoy and tested in the Yellow China Sea. When the peak wave height is greater than 0.6 m, the maximum peak-to-peak output voltage is 15.9 V. The corresponding output power is as high as 0.13 W and the maximum power density is 0.21 mW/cm 3 , where the internal resistance of the OWEH is 122 . Due to the high performance and adaptability, the OWEH can potentially power many low power components, which opens a promising way for improving the life of ocean buoys. Considering the small dimension of 10 × 10 × 6.3 cm 3 , this OWEH can be mounted inside most buoys easily and realize the self-powered ocean buoys in the near future.INDEX TERMS Ocean wave energy harvester (OWEH), swing body, electromagnetic, power management circuit, self-powered ocean buoy.
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