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Papers by Joshua Sunday
Electrochemical power sources have motivated intense research efforts in the development of alter... more Electrochemical power sources have motivated intense research efforts in the development of alternative
‘green’ power sources for ultra-low powered bioelectronic devices. Biofuel cells employ immobilized
enzymes to convert the available chemical energy of organic fuels directly into electricity. However,
biofuel cells are limited by short lifetime due to enzyme inactivation and frequent need to incorporate
mediators to shuttle electrons to the final electron acceptor. In this context, other electrochemical power
sources are necessary in energy conversion and storage device applications. Here we report on the
fabrication and characterization of a membrane-free aluminium/phosphate cell based on the activation
of aluminium (Al) using ZnO nanocrystal in an Al/phosphate cell as a ‘green’ alternative to the traditional
enzymatic biofuel cells. The hybrid cell operates in neutral phosphate buffer solution and physiological
saline buffer. The ZnO modifier in the phosphate rich electrolyte activated the pitting of Al resulting in
the production of hydrogen, as the reducing agent for the reduction of H2PO4
ions to HPO3 2 ions at a
formal potential of 0.250 V vs. Ag/AgCl. Specifically, the fabricated cell operating in phosphate buffer
and physiological saline buffer exhibit an open-circuit voltage of 0.810 V and 0.751 V and delivered a
maximum power density of 0.225 mW cm2 and 1.77 mW cm2, respectively. Our results demonstrate
the feasibility of generating electricity by activating Al as anodic material in a hybrid cell supplied with
phosphate rich electrolyte. Our approach simplifies the construction and operation of the electrochemical
power source as a novel “green” alternative to the current anodic substrates used in enzymatic
biofuel cells for low power bioelectronics applications.
A simple energy harvesting strategy has been developed to selectively catalyze glucose in the pre... more A simple energy harvesting strategy has been developed to selectively catalyze glucose in the presence of
oxygen in a glucose/O2 fuel cell. The anode consists of an abiotic catalyst Al/Au/ZnO, in which ZnO seed
layer was deposited on the surface of Al/Au substrate using hydrothermal method. The cathode is
constructed from a single rod of platinum with an outer diameter of 500 mm. The abiotic glucose fuel cell
was studied in phosphate buffer solution (pH 7.4) containing 5 mM glucose at a temperature of 22 C. The
cell is characterized according to its open-circuit voltage, polarization profile, and power density plot.
Under these conditions, the abiotic glucose fuel cell possesses an open-circuit voltage of 840 mV and
delivered a maximum power density of 16.2 mW cm2 at a cell voltage of 495 mV. These characteristics
are comparable to biofuel cell utilizing a much more complex system design. Such low-cost lightweight
abiotic catalyzed glucose fuel cells have a great promise to be optimized, miniaturized to power bioimplantable
devices.
Glucose oxidase was immobilized using a poly (hydroxyethylmethacrylate)-based hydrogel composite ... more Glucose oxidase was immobilized using a poly
(hydroxyethylmethacrylate)-based hydrogel composite material
containing polyethylene glycol and cross-linked with
tetraethyleneglycol diacrylate onto a ZnO-modified microdiamond
biosensor. The ZnO-modified biosensor was grown by
hydrothermal decomposition on array of gold patterned microdiamonds
with an electroactive area of 18.8 mm2. The morphology
of the ZnO-modified electrode was characterized by scanning
electron microscope. A potential of +0.7 V versus Ag/AgCl
reference electrode was applied to the biosensor. The hydrogel
composite ZnO-modified microdiamond biosensor exhibited a
linear dynamic range from 0.01 to 15 mM and a reproducible
sensitivity of 31.4 μA/mM cm2. The experimental detection limit
was 0.01 mM with a rapid response time of <2 s.
Electrochemical power sources have motivated intense research efforts in the development of alter... more Electrochemical power sources have motivated intense research efforts in the development of alternative
‘green’ power sources for ultra-low powered bioelectronic devices. Biofuel cells employ immobilized
enzymes to convert the available chemical energy of organic fuels directly into electricity. However,
biofuel cells are limited by short lifetime due to enzyme inactivation and frequent need to incorporate
mediators to shuttle electrons to the final electron acceptor. In this context, other electrochemical power
sources are necessary in energy conversion and storage device applications. Here we report on the
fabrication and characterization of a membrane-free aluminium/phosphate cell based on the activation
of aluminium (Al) using ZnO nanocrystal in an Al/phosphate cell as a ‘green’ alternative to the traditional
enzymatic biofuel cells. The hybrid cell operates in neutral phosphate buffer solution and physiological
saline buffer. The ZnO modifier in the phosphate rich electrolyte activated the pitting of Al resulting in
the production of hydrogen, as the reducing agent for the reduction of H2PO4
ions to HPO3 2 ions at a
formal potential of 0.250 V vs. Ag/AgCl. Specifically, the fabricated cell operating in phosphate buffer
and physiological saline buffer exhibit an open-circuit voltage of 0.810 V and 0.751 V and delivered a
maximum power density of 0.225 mW cm2 and 1.77 mW cm2, respectively. Our results demonstrate
the feasibility of generating electricity by activating Al as anodic material in a hybrid cell supplied with
phosphate rich electrolyte. Our approach simplifies the construction and operation of the electrochemical
power source as a novel “green” alternative to the current anodic substrates used in enzymatic
biofuel cells for low power bioelectronics applications.
A simple energy harvesting strategy has been developed to selectively catalyze glucose in the pre... more A simple energy harvesting strategy has been developed to selectively catalyze glucose in the presence of
oxygen in a glucose/O2 fuel cell. The anode consists of an abiotic catalyst Al/Au/ZnO, in which ZnO seed
layer was deposited on the surface of Al/Au substrate using hydrothermal method. The cathode is
constructed from a single rod of platinum with an outer diameter of 500 mm. The abiotic glucose fuel cell
was studied in phosphate buffer solution (pH 7.4) containing 5 mM glucose at a temperature of 22 C. The
cell is characterized according to its open-circuit voltage, polarization profile, and power density plot.
Under these conditions, the abiotic glucose fuel cell possesses an open-circuit voltage of 840 mV and
delivered a maximum power density of 16.2 mW cm2 at a cell voltage of 495 mV. These characteristics
are comparable to biofuel cell utilizing a much more complex system design. Such low-cost lightweight
abiotic catalyzed glucose fuel cells have a great promise to be optimized, miniaturized to power bioimplantable
devices.
Glucose oxidase was immobilized using a poly (hydroxyethylmethacrylate)-based hydrogel composite ... more Glucose oxidase was immobilized using a poly
(hydroxyethylmethacrylate)-based hydrogel composite material
containing polyethylene glycol and cross-linked with
tetraethyleneglycol diacrylate onto a ZnO-modified microdiamond
biosensor. The ZnO-modified biosensor was grown by
hydrothermal decomposition on array of gold patterned microdiamonds
with an electroactive area of 18.8 mm2. The morphology
of the ZnO-modified electrode was characterized by scanning
electron microscope. A potential of +0.7 V versus Ag/AgCl
reference electrode was applied to the biosensor. The hydrogel
composite ZnO-modified microdiamond biosensor exhibited a
linear dynamic range from 0.01 to 15 mM and a reproducible
sensitivity of 31.4 μA/mM cm2. The experimental detection limit
was 0.01 mM with a rapid response time of <2 s.