Bipolar electrochemiluminescence on thread: A new class of electroanalytical sensors

This paper introduces a new and simple concept for fabricating low-cost, easy-to-use capillary microchannel (CMC) assisted thread-based microfluidic analytical devices (CMCA-μTADs) for bipolar electrochemiluminescence (BP-ECL) application. The thread with patterns of carbon screen-printed electrodes and bare thread zones (BTZs) is embedded into a CMC. Such CMCA-μTADs can produce a strong and stable BP-ECL signal, and have an extremely low cost ($0.01 per device). Interestingly, the CMCA-μTADs are ultraflexible, and can be bent with a 135° bending angle at the BTZ or with a 150° bending angle at the middle of bipolar electrode (BPE), with no loss of analytical performance. Additionally, the two commonly-used ECL systems of Ru(bpy)32+/TPA and luminol/H2O2 are applied to demonstrate the quantitative ability of the BP-ECL CMCA-μTADs. It has been shown that the proposed devices have successfully fulfilled the detection of TPA and H2O2, with detection limits of 0.00432 mM and 0.00603 mM, respectively. Based on the luminol/H2O2 ECL system, the CMCA-μTADs are further applied for the glucose measurement, with the detection limit of 0.0205 mM. Finally, the applicability and validity of the CMCA-μTADs are demonstrated for the measurements of H2O2 in milk, and glucose in human urine and serum. The results indicate that the proposed devices have the potential to become an important new tool for a wide range of applications.