Biomedical Engineering Reference
In-Depth Information
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Durometer dial reading (Shore OO)
Figure 4.37
Durometer dial reading scale OO versus Young's modulus of soft objects is plotted
Shaker
Reference
load cell
MEMS
array
sensor
Figure 4.38
MEMS sensor being tested using an electrodynamic shaker
the last as a medium-hard object. In contrast to the finite element results, a moderate
cross talk between three channels was observed. This cross talk can be attributed to both
mechanical and electrical phenomena. The dynamic force applied to a beam can induce
some vibration into adjacent beams, which causes some output from other channels.
On the electrical side, each sensing element comprised two electrodes and associated
wiring, therefore 10 wires had to be used that could potentially affect other channels.
Figure 4.39 shows the output of the middle PVDF films for three different soft objects
with softness numbers 10, 43, and 70 on the Shore OO scale, when a distributed load of
111 kPa at 20 Hz was applied. The results of the finite element model, used to determine
these material properties, are also added to the figure for comparison. As mentioned earlier,
some level of cross talk was observed, recorded, and shown in Figure 4.40. Similar to
the previous test, a sinusoidal distributed load at 20 Hz was applied to the first beam and
