Biomedical Engineering Reference
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(a)
e
-
R
Hydrogel
matrix
Glucose
H
+
C
6
H
12
O
6
Carbon
C
6
H
12
O
7
e
-
Oxygen
Platinum
catalyst
Anode detail
Anode
Membrane
(glucose permeable)
O
2
-Selectice
cathode
Impermeable
surface
(b)
Anode:
C
6
H
12
O
6
+ H
2
O
→
C
6
H
12
O
7
+ 2 H
+
+ 2 e
-
Cathode:
1/2 O
2
+ 2H
+
+ 2 e
-
→
H
2
O
Overall:
C
6
H
12
O
6
+ 1/2 O
2
→
C
6
H
12
O
7
FIGURE 13.1
(a) A schematic of an abiotic biofuel cell powered by glucose using an oxygen-
selective air electrode as a cathode (positive electrode) and a hydrogel matrix
embedded with carbon-supported Pt catalyst to oxidize glucose to gluconic
acid to harness electricity and power a small implant, (b) the electrochemical
reactions occur in the cell. (Reprinted from Kerzenmacher, S., Ducree, J.,
Zengerle, R., and von Stetten, F.,
J. Power Sour.,
182, 2008. With permission
from Elsevier.)
Potential merits of these enzymatic or microbial systems may include
(anticipated low) cost and almost unlimited supply of biocatalytic species
that can be regenerated through reproduction, less requirements for fuel purity
due to better selectivity but also avoidance to intermediate poisoning (such
as the CO poisoning on Pt-based catalysts), fuel flexibility (from hydrogen
to carbohydrates), adaptability to improved performance by bioengineering,
and possibility of self-assembly to allow
in situ
fabrication (on unique elec-
trode surfaces). The foundation of many biosensors, bioreactors, and biofuel
cells is established on bioelectrocatalysis, an important concept that couples
enzymatic reactions with electrochemical ones. A recent review by Ikeda and
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