A PCB-based electronic ELISA system for rapid, portable infectious disease diagnosis

In this paper an amperometric electrochemical detection method is demonstrated and implemented using exclusively Printed Circuit Board (PCB)-based technologies. A portable, reconfigurable, multichannel amperometric data-acquisition board has been designed and fabricated, dedicated to the measurement of current-input signals delivered by the PCB-based biosensor. The electronic read-out circuit is able to provide constant biasing voltages to the amperometric sensor, measure in real-time the sensor's output currents, digitise them using high-accuracy Analog-to-Digital Converters (ADCs) and send the binary data to the user either through a USB2.0 interface or via an on-board TFT touch-screen. In order to validate the robustness and accuracy of the combined system, proof-of-concept amperometric experiments have taken place using our custom-made PCB-based system and standard electrochemical substrates. The results obtained have been cross-validated by means of standard colorimetric analysis and their differences have been highlighted and analyzed

Towards a smartphone-aided electronic ELISA for real-time electrochemical monitoring

This paper details the design and fabrication of a portable, smartphone-integrated electronic platform, tailored to read-out electronic ELISA (eELISA) data from printed circuit board (PCB)-based sensors. The instrument features eight independent, re-configurable current input channels, each consisting of a low-noise transimpedance amplifier (TIA) and filtering stage coupled to low-noise switch ICs for automatic current range detection. A bipolar, 16-bit resolution voltage-input analog-to-digital converter (ADC) has been employed for digitisation of converted current values received from the analogue front-end. In addition, a bipolar, 12-bit resolution digital-to-analog converter (DAC) combined with standard three-electrode potentiostats provides wide range biasing voltages to the amperometric sensors. The resulting digital data is transmitted via serial interface to an Android-based smartphone, where an ergonomic user interface guides the operator through the detection process. The customised Android application (App) provides real-time monitoring of the electrochemical cell and stores returned biochemical data on the device once measurement is complete

A dual switched-capacitor integrator architecture for versatile, real-time amperometric biosensing

In this paper, a versatile, re-programmable, current-input bioinstrumentation board is presented for electrochemical amperometric measurements. The proposed instrument has been fabricated on a six layer printed circuit board (PCB) and exploits dual switched-capacitor (SC) integration and sample-and-hold (SH) techniques. It comprises off-the-shelf switch and amplifier ICs and a commercially available FPGA-based DSP unit for digital signal control and synchronisation. It features eight amperometric channels, has a dynamic current range of 100dB, can be powered-up by a USB port or a 5V battery and is portable, with dimensions of 110×110 mm2. An onboard digital-to-analog converter (DAC) combined with standard three-electrode potentiostats can provide precise, programmable biasing voltages to eight amperometric biosensors simultaneously. Validation of the robustness and accuracy of the proposed system is demonstrated by proof-of-concept amperometric measurements using a high-precision Keithley 6221 current source and NaCI solution on a PCB-based sensor

An Assay System for Point-of-Care Diagnosis of Tuberculosis using Commercially Manufactured PCB Technology

Rapid advances in clinical technologies, detection sensitivity and analytical throughput have delivered a significant expansion in our knowledge of prognostic and diagnostic biomarkers in many common infectious diseases, such as Tuberculosis (TB). During the last decade, a significant number of approaches to TB diagnosis have been attempted at Point-of-Care (PoC), exploiting a large variation of techniques and materials. In this work, we describe an electronics-based Enzyme-Linked ImmunoSorbent Assay (eELISA), using a Lab-on-a-Printed Circuit Board (LoPCB) approach, for TB diagnosis based on cytokine detection. The test relies upon an electrochemical (amperometric) assay, comprising a high-precision bioinstrumentation board and amperometric sensors, produced exclusively using standard PCB manufacturing processes. Electrochemical detection uses standard Au and Ag electrodes together with a bespoke, low-power, multichannel, portable data-acquisition system. We demonstrate high-performance assay chemistry performed at microfluidic volumes on Au pads directly at the PCB surface with improved limit of detection (~10 pg/mL) over standard colorimetric ELISA methods. The assay has also been implemented in plasma, showing the utility of the system for medical applications. This work is a significant step towards the development of a low-cost, portable, high-precision diagnostic and monitoring technology, which once combined with appropriate PCB-based microfluidic networks will provide complete LoPCB platforms

A Novel Microfluidic Point-of-Care Biosensor System on Printed Circuit Board for Cytokine Detection

Point of Care (PoC) diagnostics have been the subject of considerable research over the last few decades driven by the pressure to detect diseases quickly and effectively and reduce healthcare costs. Herein, we demonstrate a novel, fully integrated, microfluidic amperometric enzyme-linked immunosorbent assay (ELISA) prototype using a commercial interferon gamma release assay (IGRA) as a model antibody binding system. Microfluidic assay chemistry was engineered to take place on Au-plated electrodes within an assay cell on a printed circuit board (PCB)-based biosensor system. The assay cell is linked to an electrochemical reporter cell comprising microfluidic architecture, Au working and counter electrodes and a Ag/AgCl reference electrode, all manufactured exclusively via standard commercial PCB fabrication processes. Assay chemistry has been optimised for microfluidic diffusion kinetics to function under continual flow. We characterised the electrode integrity of the developed platforms with reference to biological sampling and buffer composition and subsequently we demonstrated concentration-dependent measurements of H₂O₂ depletion as resolved by existing FDA-validated ELISA kits. Finally, we validated the assay technology in both buffer and serum and demonstrate limits of detection comparable to high-end commercial systems with the addition of full microfluidic assay architecture capable of returning diagnostic analyses in approximately eight minutes