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 0.00432mM and 0.00603mM, respectively. Based on the luminol/H₂O₂ ECL system, the CMCA-μTADs are further applied for the glucose measurement, with the detection limit of 0.0205mM. 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.