Electro-fluidic timer for event control in paper-based devices

Abstract

In this paper, we present a simple yet smart electro-fluidic platform that enables automatic time control in a very affordable and simple manner. The system is based on the electric detection of a fluid front when it crosses a particular area of a paper strip. The detection can be used to trigger the sequential activation or deactivation of different electronic modules (heating of molecular diagnostics, time interval detection, or readout of test results) with an accuracy within the range of minutes. The whole system is implemented with a few number of discrete electronic components such as transistors, resistors and capacitors that, if required, can be totally fabricated using printed electronics technology. This platform opens new possible applications for paper-based point-of care (POC) diagnostic devices and enables the possibility of these devices to introduce time control functions without the need for any external instrumentation and human action.