Conclusion
In summary, we have developed a flexible strain sensor with high
sensitivity and fast response based on PDMS film encapsulated optical
microfiber coupler structure. The CR between the two output fibers of
the microfiber coupler has been adopted to realize weak strain
demodulation. This flexible strain sensor exhibits an ultrahigh strain
sensitivity (gauge factor, GF=900), a detection limit of 0.001%,
ultrafast response time (<0.167 ms) and superior durability
and stability (>10 000 cycles). The optical loss parameter
has been adopted as the second measurand with CR simultaneously, so as
to expand the strain sensing range from 0.034% to 0.45%. These
superior sensing properties make this flexible microfiber coupler sensor
feasible for wearable photonics healthcare applications, such as the
accurate detection of arterial pulse, ant crawling and human voice. This
proposed flexible microfiber coupler sensor paves the way towards future
wearable optical devices for highly sensitive sensors applications
including personalized monitoring of cardiovascular system,
human-machine interfaces, soft robotics and artificial intelligence.