Page 135 - Organic Electronics in Sensors and Biotechnology

112 Cha pte r T h ree

V = –5 V Forced extention
d
–110.0n V = –80 V
g
–109.0n
–108.0n Unbent state
l d (A) –107.0n
–106.0n Bending
–105.0n
–104.0n Clenching
0 10 20 30 40 50 60
Time (s)
FIGURE 3.21 I vs. time monitored at V =−5 V and V =−80 V for the fi nger
d d g
joint bending detection experiment.

FIGURE 3.22 Application of a fi eld-effect strain sensor to the elbow joint
bending detection.

Changes were reversible even after numerous measurements, and
the device response is reproducible, reversible, and prompt enough to
be used to monitor relatively fast movements. In Fig. 3.22 a totally
flexible mechanical sensor was used to detect the elbow joint move-
ments. In this case, a device was glued to an elastic band and used for
monitoring elbow bending. In Fig. 3.23 an example of the obtained
results is shown.
We also tested our devices to detect the breathing activity. The
sensor was mounted on a wearable elastic band placed around the
diaphragm area of a volunteer, as shown in Fig. 3.24.
The sensor was able reveal variation in the breathing activity due
to apnea, cough, laugh, hiccups, etc. In Figs. 3.25 and 3.26 examples
of the obtained results for different breathing movements are shown.