Biomedical Engineering Reference
In-Depth Information
Silica glass
ITO coating
Conductive epoxy
Polyester spacer
bR thin film
ITO coating
Silica glass
FIGURE 5.4
The ITO electrode/bR film/ITO electrode structure of the dried bR-based photocell.
Lipid
between
molecules
ITO electrode
Output
C
1
R
1
C
M
Complete bR
film
R
M
R
S
+
−
E
ph
(
t
)
ITO electrode
Oriented bR
molecule
FIGURE 5.5
Schematic diagram of the physical bR photocell and equivalent RC circuit for the photovoltage generated.
nm (blue) to 568 nm (red) (Melles Griot, 35KAP431-220). The output power for individual
wavelength can be tuned over a wide range. Furthermore, it was observed that the bR
photocells can response to extremely small change of light intensity (46,47).
To illustrate how a neural network can adaptively determine a multivariate calibration
function, consider the example of the bR-based photocell described above. Recall that the
photovoltage response of the device is proportional to both the wavelength and intensity
of the incident light source. For biosensor calibration purposes, the RBF network is used
to model the relationship between photovoltage and light intensity of the bR-based pho-
tocell for five wavelengths 476, 488, 520, 530, and 568 nm. The input-output dataset is first
