Development of Arduino-based portable systems for electroanalytical detection

This work presents the development of a multi-mode electroanalytical detection system based on Arduino microcontroller board. First, a multichannel impedance readout system is designed for alternating current electrokinetics (ACEK) based capacitive sensing. ACEK phenomena on 100μm interdigitated electrodes are observed via fluorescent particles as well as bioparticles, which illustrate the mechanisms of ACEK target enrichment for the capacitive sensing method. I2C multiplexer is applied to allow multiple impedance converters to work together providing continuous AC signals for ACEK capacitive sensing. Second, an electronic nose composed of three modules including a gas sensor array, a circuit for signal acquisition integrated with Arduino microcontroller board, and a PC for signal analysis is designed. A backpropagation neural network with one hidden layer and one output layer is trained to classify gas samples from binary and ternary mixtures of acetone, ethanol, and isopropyl alcohol. Three features are extracted from transient signals in a short time (as compared to steady-state signals), and the classification is done within 1 minute after gas reached the surface of the sensors. Third, a low-cost portable potentiometric sensing system for the detection of heavy metals in water is developed and assessed by testing with hand-fabricated all-solid-state Pb²⁺ and Cd²⁺ ion-selective electrodes (ISEs). To avoid the use of a multimeter, an extended-gate metal-oxide-semiconductor field-effect transistor (MOSFET) is applied to the readout circuit and integrated with an Arduino microcontroller board. ALD1106 matched MOSFET pair is chosen for differential sensing to overcome the possible drift problem of ISEs. With a threshold voltage of 0.7 V while operating at the subthreshold region, the MOSFET could be biased via a potentiometer to avoid the use of a voltage source. Last, the three different analytical detections are integrated into one multi-mode system in the design.