Automatic smartphone-based microfluidic biosensor system at the point of care

Alternating Current Voltammetry at a Bipolar Electrode with Smartphone Luminescence Imaging for Point‐of‐Need Sensing

“…While bipolar electrodes (BPEs) have been applied to many sensing motifs, their sensitivity and specificity are limited by the lack of diversity in voltammetric methods that have been developed for these wireless electrodes. In this study, electrochemiluminescence (ECL) from the co-oxidation of Ru(bpy) 3 2 + and tripropylamine (TPA) is evaluated as a reporting reaction for alternating current voltammetry (ACV) on a BPE at frequencies of 1.0 Hz and 5.0 Hz. We observe sinusoidal alternating luminescence that follows a similar trend to that of the simultaneously monitored current -a plot of the amplitude versus potential approximates a bellshaped curve.…”

“…[2] A growing body of work is dedicated to adapting smartphones as PON tools because of their low cost, portability, and accessibility. [3][4][5][6][7][8][9] Detection of colorimetric, [5] fluorescent, [5] electrochromic, [4] and luminescent [6][7][8][9] signals with a smartphone have been demonstrated, and there are several examples of smartphone detection of reporting reactions on BPEs in the literature. [7,9] However, some of the most sensitive and information-rich voltammetric methods employ an alternating sinusoidal or square-wave potential, which are currently not developed for BPEs.…”

“…[18][19][20][21][22][23] Of these, few have explored alternating current. Of note is the Shannon group's use of a square wave potential to drive ferricyanide reduction, and separately for DNA sensing, at the cathode of a Au BPE with an ECL readout at the anode, using Ru(bpy) 3 2 + and sodium oxalate in aqueous solution. [18] The ECL response to a 0.5 Hz square wave signal was recorded and averaged over several oscillations to improve the signal-to-noise ratio.…”

“…[24] The results of these studies indicate that the ECL response to an AC potential is faster, [24] more efficient, [24] and more sustained [25] than that obtained with a DC potential. However, the response of aqueous ECL of Ru(bpy) 3 2 + with co-reactant tripropylamine (TPA) to a sinusoidal AC potential has not been evaluated for similar features.…”

“…In the present study, we evaluate the fidelity of the light intensity emitted by ECL, arising from the co-oxidation of Ru (bpy) 3 2 + and TPA in an aqueous environment, to the magnitude of faradaic current obtained during ACV at a pyrolyzed photoresist film (PPF) electrode. [27] In contrast to previous work, we report on an AC voltammetric technique, not an amperometric technique, and at an applied frequency of 5.0 Hz, a higher frequency than previously demonstrated on BPEs.…”