Improvement of decompression unit in autonomous drug release system for blood sugar control

Improvement of the decompression unit “Organic engine” that can generate kinetic energy from the chemical energy of chemicals such as glucose has been proposed and tested. The organic engine was fabricated by separating a cylindrical cell into a top-cell for gas-phase and a bottom-cell for liquid-phase, which separated by glucose oxidase immobilized membrane. Decompression was generated by catalysis of glucose oxidation. However, the concentration of glucose to actuate the system was 100 mmol/L that is too high compared to the human blood glucose concentration to apply it for artificial pancreas-like devices. In order to increase decompression rate, methods to enlarge area of the enzyme membrane per volume of the gas chamber were proposed and evaluated. Decompression rate in modified cell on 25 mmol/L glucose solution was equal to that of in conventional cell (-7.2 Pa・cm/s) on 100 mmol/L glucose solution. As a result, three times higher output was enable to actuate on low glucose concentration close to blood sugar.