Miniature sono-electrochemical platform enabling effective and gentle electrode biofouling removal for continuous sweat measurements

Abstract

• Sono-electrochemical lab-on-a-chip device with gigahertz bulk acoustic resonator. • Acoustic actuation in-situ releasing fouled electrode′s electrochemical activity. • Non-invasiveness to intrinsic film electrode and the decorated nanoparticles. • Continuous and repeatedly electrochemical measurements to human sweat. Developing miniature smart electrochemical sweat sensors to perform continuous and noninvasive health diagnosis at molecule level is in the spotlight. Sensor's biofoulings hinder the targets' approaching, decreasing the detection sensitivity over time and further limiting the accurate analysis. Effective cleaning to remove biofoulings on electrochemical sensors is a main challenge and needs to overcome urgently for such purpose. We propose a miniature sono-electrochemical platform utilizing submillimeter gigahertz acoustic resonator to effectively clean away the biofoulings and release sensors inherent electrochemical activities. Resonator induced super strong fluid streaming can completely and repeatedly remove sweat biofoulings from gold electrode surface, leading to 100% recovery of sensor’s activities for continuous reliable measurements. Compared with common sensor renewal strategies, such as acidic or basic solution cleaning, mechanical polishing, traditional low frequency ultrasound treatment, this electrode surface renewal technique is stable, mathematically predictable, effective and gentle so that it does not cause any destructions to inherent electrode surface, and therefore the sensed electrochemical signals on raw and cleaned electrodes are comparable and improvable with no unexpectable deviation. Together with submillimeter size of the resonator, it shows potential to be integrated within wearable electroanalytical microfluidics for developing smart device to carry out continuous health diagnosis.