Accuracy Evaluation of a Novel Reusable Patch Pump Prototype.

A prototype of an insulin patch pump that operates with a double pump mechanism was tested. Accuracy of bolus delivery of 0.2 U and 1.0 U, and a basal rate of 1.0 U/h were evaluated with a microgravimetric method. In addition, occlusion detection time at basal rates of 0.1 U/h and 1.0 U/h was assessed. Mean deviation from target was lower than 2% for both bolus sizes. Regarding basal rate accuracy, mean deviation over 72 hours was lower than 1%. Occlusion detection occurred in less than 30 minutes with both basal rates. Our study results suggest that the tested pump prototype provides delivery accuracy and occlusion detection that is similar or even better compared to all commercially available pumps tested with a similar experimental approach.

Size-selective diffusion in nanoporous but flexible membranes for glucose sensors.

A series of nanoporous membranes prepared from polyethylene-block-polystyrene were applied for size-selective diffusion of glucose and albumin molecules. Millimeter-sized test cells for characterization of such molecular diffusions were designed assuming an implantable glucose sensor. The prepared nanoporous membrane exhibits excellent flexibility and toughness compared to conventional nanoporous membranes of brittle alumina. Pore size of the membranes could be controlled from 5 to 30 nm by varying preparation conditions. All of these nanoporous membranes prepared in this study let glucose pass through, indicating a continuous pore connection through the entire thickness of the membrane in a few tens of micrometers. In contrast, membranes prepared under optimum conditions could perfectly block albumin permeation. This means that these vital molecules having different sizes can be selectively diffused through the nanoporous membranes. Such a successful combination of size selectivity of molecular diffusion in nanoscale and superior mechanical properties in macroscale is also beneficial for other devices requesting down-sized manufacture.