Wireless electrochemiluminescent biosensors: Powering innovation with smartphone technology

Energy supply and sensor response acquisition can be performed wirelessly, enabling biosensors as Internet of Thing (IoT) tools by linking wireless power supply and electrochemical sensors. Here, we used the electromagnetic induction method to clarify the conditions under which electrochemiluminescence is induced by a simple potential modulation circuit without an integrated circuit on the electrode chip that receives the power. Initially, the potential waveform obtained in a circuit with inductance and capacitance components that resonate with the transmission frequency and a diode for rectification was investigated to clarify the conditions inducing an electrochemiluminescence reaction at the printed electrode. A high-sensitivity complementary metal-oxide semiconductor camera built into the smartphone wirelessly detected the luminescence generated on the electrode chip. The images were quantitatively evaluated using open-source image analysis software which determine the sensitivity of detecting hydrogen peroxide. Glucose oxidase (GOD) encapsulated in a matrix of chitosan polymers and photocrosslinkable polymers was immobilized on a mass-producible and inexpensive printed electrode to maintain high activity. The immobilized membrane suppressed luminescence when immobilized on the working electrode; therefore, the enzyme was immobilized on the counter electrode for glucose measurement over a wide concentration. Thus, luminol electrochemiluminescence was induced on the electrode chip by wireless power supply from a smartphone. Human serum and artificial sweat samples were tested and indicated possibility for actual applications. In this way a fully wireless biosensor was developed with potential as an IoT biosensor.