Abstract
We have already developed a new vessel access type glucose sensor, which can automatically measure blood glucose levels up to 700mg/dl without sampling and diluting blood. A proportional controll type closed-loop artificial β-cell system has been constructed of the sensor, a micro insulin infusion pump and the controll circuits which have an integrator, a comparator and a pulse generator to supply the power for the pump. The system has been examined in dogs.
In this system, the infusion interval of the pump is controlled by the sensor output current. When the B. G. L. is normal, the infusion pump is operated and infuses about 14μl every 5 minutes. If the sensor output becomes higher, i. e. higher B. G. L., the infusion rate becomes faster to fall the B. G. L.
The system was checked by an in vitro test using high Meg-ohm resisters instead of the sensor, and showed good results.
In vivo, this system has performed so well that the reciprocal of infusion interval showed a fairly analogous profile to one of the sensor out put, and the infusion volume of insulin per every 5 minutes also showed the same profile.
The assembled system, therefore, may be promising as a closed-loop artificial β-cell.
