Design and fabrication of new microfluidic experimental platform for ultrasensitive heavy metal ions (HMIs) sensing

We proposed a system that includes the thiol-based microfabricated piezoresistive sensors array with ion-selective self-assembled monolayers (SAMs) where heavy metal ions (HMIs) and thiol interaction starts bending the microcantilever and results in a change of resistance. This change of resistance is directly proportional to the mass of HMIs to be detected. In the proposed system, microcantilever has SAM coatings to test sensitivity and selectivity and to identify the suitable thiols for targeted HMI. Also, there was one without SAM coating that was used as a reference for error detection. The experimental analysis shows excellent response to the selective detection of Hg2+ ions in the presence of other HMIs. The change resistance (ΔR) is around 250-300 Ω for Hg2+ ions with homocysteine (Hcys)-pyridinedicarboxylic acid (PDCA). From the experimental results, it is clear that this technique has the potential and capability to selectively detect Hg2+ ions as low as 0.75 ng/mL (3.73 pM/mL) and outperform other methods.