K. Mathwig and S. G. Lemay
Pushing the Limits of Electrical Detection of Ultralows Flows in Nanofluidic Channels
Micromachines 4 (2013) 138.
Special Issue Selected papers from 1st International Conference on Microfluidic Handling Systems.
This paper presents improvements in flow detection by electrical cross-correlation spectroscopy. This new technique detects molecular number fluctuations of electrochemically active analyte molecules as they are transported by liquid flow through a nanochannel. The fluctuations are used as a marker of liquid flow as their time of flight in between two consecutive transducers is determined, thereby allowing for the measurement of liquid flow rates in the picoliter-per-minute regime. Here we show an enhanced record-low sensitivity below 1 pL/min by capitalizing on improved electrical instrumentation, an optimized sensor geometry and a smaller channel cross section. We further discuss the impact of sensor geometry on the cross-correlation functions.