Biosupercapacitors for powering oxygen sensing devices

•3 biofuel cells in a series were used to power a minipotentiostat/oxygen sensor device•3 biofuel cells connected in a series give OCP of 2 V and power 2 mW.•Supercapacitive materials — carbon nanotubes and nanocellulose/polypyrrole composite allowed charge-storage in the cell.•Pulsed mode including power supply and charge regeneration steps was advantageous for long term powering of sensing device.

A biofuel cell comprising electrodes based on supercapacitive materials — carbon nanotubes and nanocellulose/polypyrrole composite was utilized to power an oxygen biosensor. Laccase Trametes versicolor, immobilized on naphthylated multi walled carbon nanotubes, and fructose dehydrogenase, adsorbed on a porous polypyrrole matrix, were used as the cathode and anode bioelectrocatalysts, respectively. The nanomaterials employed as the supports for the enzymes increased the surface area of the electrodes and provide direct contact with the active sites of the enzymes. The anode modified with the conducting polymer layer exhibited significant pseudocapacitive properties providing superior performance also in the high energy mode, e.g., when switching on/off the powered device. Three air–fructose biofuel cells connected in a series converted chemical energy into electrical giving 2 mW power and open circuit potential of 2 V. The biofuel cell system was tested under various externally applied resistances and used as a powering unit for a laboratory designed two-electrode minipotentiostat and a laccase based sensor for oxygen sensing. Best results in terms of long time measurement of oxygen levels were obtained in the pulse mode − 45 s for measurement and 15 min for self-recharging of the powering unit.