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.
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Zevenbergen, M.A.G.; Wolfrum, B.L.; Goluch, E.D.; Singh, P.S.; Lemay, S.G. Fast electron transfer kinetics probed in nanofluidic channels. J. Am. Chem. Soc. 2009, 131, 11471–11477.
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Mathwig, K.; Mampallil, D.; Kang, S.; Lemay, S.G. Detection of Sub-Picoliter-per-Minute Flows by Electrochemical Autocorrelation Spectroscopy. In Proceedings of the 16th International Conference on Miniaturized Systems for Chemistry and Life Sciences (MicroTAS), Okinawa, Japan, 28 October–1 November 2012; pp. 28–30.
