Design of potentiostat and fluidic chamber for biosensing application

Abstract

The World Health Organization (WHO) identifies dengue as one of the top ten threats to global health. Statistics in Malaysia show a 148.4 % rise in dengue cases in 2022. Delay in dengue diagnosis may affect severity and mortality of the patient. Early and rapid dengue diagnosis is critical for clinical management, epidemiological strategies and appropriate patient care. There are limitations in both conventional and modern dengue diagnostics. Currently, Rapid Test Kits (RTK) produce fast results and can be used for detection of dengue but cannot detect the patient’s susceptibility to dengue haemorrhagic fever and dengue shock syndrome. Reverse Transcription Polymerase Chain Reaction (RT-PCR) tests can distinguish different dengue variants but are time consuming and costly. In this work, an alternative technique using an Integrated Electrochemical Quartz Crystal Microbalance (IEQCM) biosensor with a potentiostat. This rapid and early detection method senses NS1 antigen, provides electronic readouts, and has the potential to identify different dengue variants. Potentiostats have been widely used for electrochemical detection but some of them are bulky, expensive and not suitable for Point-of-Care applications. For this work a portable and flexible potentiostat has been proposed. Unlike traditional rigid potentiostats, this design was fabricated on a flexible printed circuit board. The fabricated potentiostat can perform Cyclic Voltammetry (CV) measurements and experimental results produced ΔEp of 0.132 V, which is similar to the voltage produced by a commercial potentiostat, EmStat Pico. Next, Electrochemical Impedance Spectroscopy (EIS) measurements were done on the IEQCM sensor to detect NS1 dengue antigen. This detection was performed using EmStat Pico and it measures biological reactions between the biorecognition element (NS1 antibody) and NS1 antigen of dengue samples. The EIS measurement showed the lowest Limit of Detection (LoD) is 2.31 ng/mL and Limit of Quantitation (LoQ) is 6.99 ng/mL. When compared with previous work, with an absolute error of ~ 5 %. This indicates that the design potentiostat is a viable tool for dengue diagnosis.