Page 205 - Organic Electronics in Sensors and Biotechnology

182 Chapter Five

8
Bacteria + 1 mM glucose
30 Bacteria + 1 mM glucose + 250 μM Cu-mb
Bacteria + 1 mM glucose + 500 μM Cu-mb
6
25
1/τ (ms –1 ) 20 4 DO concentration (ppm)

2
15

10 0
0 5 10 15 20 25 30 35
Time (min)
FIGURE 5.14 The effect of Cu-mb on the respiration and survival of
~5 mg/mL B. subtilis bacteria.

of DO reached a constant level smaller than 2 ppm in ~15 min. In the
presence of 500 μM Cu-mb, the level of DO reached a constant level of
~4 ppm after ~10 min. These constant, non-zero DO levels, which
remain in the solution, indicate obliteration of the bacteria by Cu-mb;
this process is faster with increasing Cu-mb concentration, as expected,
with a higher remaining level of DO.
The foregoing initial results on monitoring the state of B. subtilis
cultures using an OLED-based DO sensor demonstrate the potential
power of a wide network of autonomous remote-controlled OLED-
based DO sensors, which would monitor foodborne pathogens and
food spoilage at key processing, transport, and distribution points of
the food industry.

5.4 OLED Sensing Platform Benefits and Issues
The foregoing review demonstrated the promise of the OLED-based
platform for monitoring oxygen and other analytes that can be moni-
tored via oxygen. The advantages of the OLED arrays include their
high brightness, design flexibility, and compatibility with glass or plas-
tic substrates and consequently with microfluidic architectures as well.
Moreover, their fabrication is facile, and their integration with the sens-
ing elements is uniquely simple. Hence, they should eventually yield
low-cost, miniaturized, field-deployable multianalyte sensor arrays for
monitoring a wide variety of analytes. The continuing advances in
OLED performance and their expanding commercialization will facili-
tate the realization of the OLED-based sensor platform.