The specially designed MNFs structure and the flexibility of PDMS endow the sensor with high sensitivity and good ductility.
Figure 1b and c show that such a coupler is sensitive to gap widths, as the output intensity changes dramatically when gap width changes slightly.
The PDMS film can isolate the sensing region from the air, thereby avoiding unpredictable signal interference caused by dust deposition and other external environmental changes. The whole structure is embedded in a PDMS film of appropriate thickness to ensure that the strain is transduced to the sensor with high fidelity. Thus, any displacement between two MNFs will be reflected upon the change of optical intensity at the output port, thereby realizing highly sensitive strain sensing. As the evanescent field decays exponentially outside the MNFs, the coupling efficiency is very sensitive to the gap between the two MNFs. Each U-shaped MNF has a diameter of 0.9 μm and bending radius of 50 μm. The authors of this article propose a highly sensitive and fast response optical strain sensor, as shown in Figure 1a. Such versatile sensors could be of great use in physiological signal monitoring, voice recognition and micro-displacement detection. The properties of fast temporal frequency response up to 30 kHz and a pressure sensitivity of 102 kPa-1 enable the sensor for sound detection. As a proof-of-concept, highly sensitive fingertip pulse measurement is realized.
The strain sensor exhibits a gauge factor as high as 64.5 for strain ≤ 0.5% and a strain resolution of 0.0012% which corresponds to elongation of 120 nm on a 1 cm long device. Recently, a highly sensitive and fast response optical strain sensor with two evanescently coupled optical micro/nanofibers (MNFs) embedded in a polydimethylsiloxane (PDMS) film is proposed. Especially, optical coupler based on evanescently coupled MNFs is a promising structure for highly sensitive optical sensing, as the coupling efficiency is strongly dependent on the ambient refractive index, the coupling length and the gap between the two adjacent MNFs. Alternatively, fiber based optical sensors offer attractive advantages compared with their electronic counterparts, including inherent electrical safety, immunity to electromagnetic interference, and small size.Īs a combination of fiber optic and nanotechnology, micro/nanofibers (MNFs) have been attracting increasing research interest due to their potential in renewing and expanding fiber optics and flexible sensors in micro/nano scale. However, the complicated processing and high sensitivity to electromagnetic disturbances bring challenges to their practical applications. Recently, various types of electric strain sensor based on microstructures such as islands structures, percolations and microcracks have been demonstrated for physiological signals detection. At present, the reported strain sensors mainly focus on high stretchability and high sensitivity under large deformation for motion detection, yet low sensitivity under micro-deformation (≤1%) may limit their applications in micro-displacement detection and weak physiological signal monitoring. It is accompanied by animated videos and audio examples to instruct you and to help ensure that you are playing accurately.Strain sensors play an important role in many applications such as flexible electronics, health monitoring, and soft robotics due to their superb response to mechanical deformations. The book includes hundreds of rhythm exercises and practice patterns, as well as melodies and duet/ensemble pieces. Improve your rhythm, sense of tempo, and reading skills with the Time Lines Music Method. Visit the MetronomeBot homepage for metronomes that count the beat, as well as metronomes that subdivide the beat. They can be used for music in any time signature. Scroll down for a complete list of links to more tempos ranging from 30 BPM to 300 BPM available for the basic online metronome.
If you need to practice at this tempo for more than nine minutes, simply reload the video, or right-click (control-click on Macs) on the video and select “Loop.” MetronomeBot is producing the tone at a steady beat for nine minutes in the Youtube video below. This metronome repeatedly produces a woodblock sound at 100 beats per minute, or 100 BPM. Home - Metronomes - Online metronome Basic metronome at 100 beats per minute
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