Conductive polylactic-acid filament for dose monitoring in syringe-less wearable infusion pump

摘要

Graphical abstractDisplay OmittedHighlights•We demonstrated the use of conductive PLA filament as a low cost and disposable dose monitoring method.•Dose monitoring is achieved via the combined impedance change of the conductive PLA filament/liquid medium column.•It allows syringe-less dispensing methods to be used in wearable infusion pumps.•Size profile limitation by the use of syringe-based dispensing methods is circumvented.•Contributes to the realization of ultra-low size profile insulin pumps.AbstractWe have demonstrated the use of conductive polylactic acid (PLA) filament for dose monitoring in a syringe-less wearable infusion pump. A channel reservoir is inlaid with conductive PLA filament. As the liquid medium is dispensed via gas pressurization by an built-in electrolysis chamber, the effective impedance of the conductive PLA filament/liquid medium column changes as well. This allows the dispensed volume to be monitored via the output voltage across a series resistor. Using 5V sinusoidal input voltage, the output voltage decreased from ∼1.3 to ∼0.13V as the dispensed volume of 0.1mol/L PBS increased from 0 to 1000μL. Similarly, the output voltage for insulin analog decreased from ∼0.64 to 0.126V for the same volume displaced. Repeated dispensing runs with 0.1mol/L PBS showed good consistency (standard deviation less than 10mV). The rate of change of the output voltage with elapsed time varied accordingly for the different flow rates (0.25–1.00mL/h or ∼4–17μL/min). At electrolysis voltages of 1.5 and 5V, the respective output voltage were 1.04 and 0.33V. These corresponded to flow rates of ∼3 and 10mL/h (∼50 and 160μL/min).