Biomedical Engineering Reference
In-Depth Information
0.05
Experimental data
Linear fit
0.04
(Slope = 1.16 × 10
-3
[
m]
-1
)
0.03
4.0
@ 0
m
@ 10
m
4.1
4.2
4.3
4.4
4.5
4.
1.90
0.02
@ 20
m
@ 30
m
@ 40
m
0.01
0.00
1.92 1.94
Bias voltage [V]
1.96
1.98
2.0
-0.01
0
10
20
Deflection (μm)
30
40
Figure 9.9
Electromechanical characterization plot for polymer nanocomposite
microcantilever.
del ecting the tip of the microcantilever with a calibrated micromanipu-
lator needle with simultaneous measurement of resistance using Keithley
4200 source measuring unit. ΔR/R for a polymer nanocomposite micro-
cantilever plotted as a function of del ection as shown in Figure
9.9 indi-
cates a del ection sensitivity of 1.1 ppm/nm. h e extracted gauge factor was
approximately 90. h e surface stress sensitivity was calculated using Eq
9.1. h e surface stress sensitivity is 7.6 × 10
-3
[N/m]
-1
which is greater than
that of an optimized silicon microcantilever and one order of magnitude
higher than that of polymer microcantilevers with Au as the strain gauge
[20] reported earlier.
9.3 Organic CantiFET
Polymer nanomechanical sensor platforms using SU-8 nanocomposite
cantilevers discussed in the previous section i nd applications in low cost
biochemical sensing owing to their high sensitivity. However, that the nano-
composite materials realized using particle dispersion techniques might
suf er from process variability issues. So a new transduction scheme was
explored that addressed this aspect by introducing a strain sensitive poly-
mer layer in a SU-8 nanomechanical cantilever sensor with reduced process
complexity and process variability. Pentacene which is a well-studied organic
