Stack of BioCells Converting ATP to Electrical Power and Possible Applications

Abstract

Plant and animals convert absorbed nutrients into the most readily available form of biochemical energy in cells - Adenosine triphosphate (ATP). Ion transporter proteins in the cell membranes hydrolyze ATP and use the energy from the reaction for ion transport across cell membranes. The BioCell is an energy conversion device inspired by ion transport through cell membranes that uses a proton-sucrose cotransporter (SUT4) to convert the chemical energy in ATP into electrical energy. Experiments on a single cell demonstrated that the BioCell behaves like a constant current power source with 10 - 22 kΩ internal resistance. The single cell developed a peak power of 0.7 μW per cm² of bilayer lipid membrane (BLM) area reconstituted with 1 mg of SUT4 and 1 μl of ATP-ase at 10 kΩ load in the external circuit. The actual peak power output from the cell was 160 nW for a BLM area of 0.079 cm² carrying 0.2 mg of SUT4 and 15 μl of ATP-ase. The 160 nW of electrical power that could be sourced from the cell with a 10 kΩ load (41 mV and 4 μA) is not sufficient to run a low power electronic device and needs to be scaled up to few microwatts. This article discusses our experimental results from stacking a BioCell in series and parallel to develop higher stack voltage and current. We observe that the cell voltage adds linearly by connecting the BioCells in series and a 10-cell stack developed a peak power of 750 nW (500 mV @ 2.5 μA observed at 265 kΩ. The peak power from the stack by connecting the cells in parallel was 1.4 μW (125 mV and 11.2 μA) at 1kΩ. The experimental results demonstrate that the power from a single cell can be scaled by connecting them in series and in parallel without appreciable losses. A survey of electronic devices indicated that a minimum of 20 μW will be required to run a demonstration application from a stack and also gives us the direction to scale the power output from a single cell.