Portable self-powered electrochemical aptasensor for ultrasensitive and real-time detection of microcystin-RR based on hydrovoltaic-photothermal coupling effect.

Coupling different energy harvesting technologies to obtain an excellent output signal is essential for the development of high-performance self-powered electrochemical sensors. Herein, a novel hydrovoltaic-photothermal coupling self-powered electrochemical aptasensing platform was designed for sensitive detection of microcystin (MC-RR) with a digital multimeter as a direct visual readout strategy. The straightforward ultrasonic method was employed to synthesize polyaniline (PANI) and bismuth oxybromide (BiOBr) nanosheets, which were then integrated as active components in a hydrovoltaic device. The unique layer structure of two-dimensional (2D) nanomaterials BiOBr can create flexible interlayer spaces to accommodate various ions and water molecules, which was beneficial to construct evaporation-driven channels. Meanwhile, the exceptional photothermal characteristics of polyaniline could accelerate the water evaporation rate, consequently boosting the migration speed of charge carriers and increasing output signal. Moreover, a digital multimeter was connected to the constructed sensor for real-time displaying the output signal. With the assistance of aptamer, a novel self-powered electrochemical aptasensing platform was constructed for sensitive detection of MC-RR. Under optimum conditions, the output signal of the hydrovoltaic-photothermal coupling cell was linearly related to the logarithm of MC-RR concentration in the range of 1 fM to 1 nM with a detection limit of 0.31 fM (S/N = 3). Furthermore, this sensor also exhibited many advantages such as high selectivity, good repeatability and portability. Such novel strategy not only offers a completely new general approach to construct high-performance self-powered devices for the detection of MC-RR, but also provides a new strategy for advancing the miniaturization and field application of self-powered electrochemical sensors.