Kan Shoji

Biofuel cell backpacked insect and its application to wireless sensing

This study investigated an enzymatic biofuel cell (BFC) which can be backpacked by cockroaches. The BFC generates electric power from trehalose in insect hemolymph by the trehalase and glucose dehydrogenase (GDH) reaction systems which dehydrogenate β-glucose obtained by hydrolyzing trehalose. First, an insect-mountable BFC (imBFC) was designed and fabricated with a 3D printer. The electrochemical reaction of anode-modified poly-L-lysine, vitamin K3, diaphorase, nicotinamide adenine dinucleotide, GDH and poly(sodium 4-styrenesulfonate) in the imBFC was evaluated and an oxidation current of 1.18 mAcm(-2) (at +0.6 V vs. Ag|AgCl) was observed. Then, the performance of the imBFC was evaluated and a maximum power output of 333 μW (285 μW cm(-)(2)) (at 0.5 V) was obtained. Furthermore, driving of both an LED device and a wireless temperature and humidity sensor device were powered by the imBFC. These results indicate that the imBFC has sufficient potential as a battery for novel ubiquitous robots such as insect cyborgs.

Diffusion refueling biofuel cell mountable on insect

This paper reports an insect mountable biofuel cell (imBFC) which generates electric power from trehalose found in insect hemolymph and refuel trehalose from insect hemolymph by diffusion automatically. First, we designed and fabricated the imBFC consisted of a connector, two chambers, a dialysis membrane and electrodes. Then, we evaluated the power density and life-time of the imBFC. The maximum power of 50.2 μW (42.9 μW/cm2) was obtained. The power output of the imBFC was maintained at more than 10 μW for 3 h. Finally, we connected a light-emitting diode (LED) device to the imBFC and succeeded to driving the LED device. The results indicate that the imBFC is a promising micro battery to power environmental monitoring micro-tools.

Insect-mountable biofuel cell with self-circulation system

This paper reports the potentiality of a semi-permanent integrated power source mounted on an insect and using trehalose, the main sugar of insect hemolymph. A self-circulation system of cockroach hemolymph powered by the dorsal vessel of a cockroach was developed for self-refueling of an insect-mountable biofuel cell (BFC) and connected to a cockroach with a tube and a check-valve. The flow rate of about 457 nL/s was obtained. Furthermore, the electrochemical reaction of the anode of the insect BFC was confirmed to take place when the chamber was mounted onto the cockroach. Finally, the insect-mountable system consisting of a flow channel, a dialysis membrane, a chamber and insect BFC was fabricated.

Biofuel cells with trehalose leading to an insect-implanted power source

This paper reports the first demonstration of a biofuel cell (BFC) using trehalose found in insect hemolymph. The analysis results by liquid chromatography-mass spectrometry (LC-MS) showed that trehalose concentration included in cockroach hemolymph (CHL) was high enough to utilize as a source of power generation. The maximum power density of 6.07 µW/cm2 was obtained from CHL with added trehalase (Tre) and mutarotase (Mut). To prevent the open-circuit voltage decrease by adsorption of proteins in the CHL, the electrodes were protected by a dialysis membrane. As a result, the open-circuit voltage was constantly kept around 300 mV for more than 30 min. Furthermore, the maximum power density was increased to 10.5 µW/cm2 by using an air diffusion biocathode.

Autonomous environmental monitoring by self-powered biohybrid robot

This paper reports the first demonstration of a self-powered environmental monitoring robot which backpacked a biofuel cell (BFC) and a micro wireless sensor module on insect. Electric power was generated from blood sugar in its hemolymph by using the BFC and temperature and humidity around it was monitored by using the wireless sensor module. Furthermore, the robot moves autonomously by the intention of insect. First, the BFC which can be backpacked cockroaches was fabricated with a 3D printer. The electrochemical reaction of the anode in the insect-mountable BFC (imBFC) was evaluated and an oxidation current of 1.18 mA/cm2 (at +0.6 V vs. Ag|AgCl) was observed. Then, the performance of the imBFC was evaluated and a maximum power output of 333 μW (at 0.5 V) was obtained. Furthermore, a wireless temperature and humidity sensor was successfully driven by the imBFC. Finally, the imBFC and the micro wireless sensor module were mounted on the insect and environmental monitoring was done by the insect. These results indicate that the insect which backpacked the self-powered battery and micro wireless sensors has sufficient potential as microrobots for environmental monitoring and searching in disasters.

Trehalose biofuel cells using insect hemolymph for insect robots

This paper repots a demonstration of an IC driving by a trehalose biofuel cell (BFC) mounted on insects. First, we evaluated a trehalose oxidized anode. Then, we fabricated an insect-mountable BFC (imBFC) and the maximum power density of 42.9 μW/cm2 was obtained from the imBFC. Finally, we demonstrated to flash a LED by the imBFC. These results showed the possibility for developing a power source integrated with insects for insect cyborgs.

Microfluidic Formation of Double-Stacked Planar Bilayer Lipid Membranes by Controlling the Water-Oil Interface

This study reports double-stacked planar bilayer lipid membranes (pBLMs) formed using a droplet contact method (DCM) for microfluidic formation with five-layered microchannels that have four micro guide pillars. pBLMs are valuable for analyzing membrane proteins and modeling cell membranes. Furthermore, multiple-pBLM systems have broadened the field of application such as electronic components, light-sensors, and batteries because of electrical characteristics of pBLMs and membrane proteins. Although multiple-stacked pBLMs have potential, the formation of multiple-pBLMs on a micrometer scale still faces challenges. In this study, we applied a DCM strategy to pBLM formation using microfluidic techniques and attempted to form double-stacked pBLMs in micro-meter scale. First, microchannels with micro pillars were designed via hydrodynamic simulations to form a five-layered flow with aqueous and lipid/oil solutions. Then, pBLMs were successfully formed by controlling the pumping pressure of the solutions and allowing contact between the two lipid monolayers. Finally, pore-forming proteins were reconstituted in the pBLMs, and ion current signals of nanopores were obtained as confirmed by electrical measurements, indicating that double-stacked pBLMs were successfully formed. The strategy for the double-stacked pBLM formation can be applied to highly integrated nanopore-based systems.

Stacked biofuel cells separated by artificial lipid bilayers

This paper reports stacked biofuel cells (SBFC) separated by artificial lipid bilayers which are bimolecular membranes and several nm membranes. First, we designed and fabricated SBFCs with a screen printer and a 3D printer. Then, we evaluated electrochemical reaction of electrodes of the SBFC and measured the output voltages of single, double, triple and quad SBFCs. Finally, we demonstrated to drive a digital clock powered by the quad SBFC. These results indicate the potentially for developing the high voltage BFC implanted in living organisms.