Highly sensitive three-dimensional interdigitated microelectrode biosensors embedded with porosity tunable hydrogel for detecting proteins

This study focused on fabricating a target-specific electrical biosensor with high sensitivity and dynamic range by embedding a hydrogel, that incorporated a much larger number of antibodies in the reaction region of the sensor, allowing all biomolecules except the target molecules to be filtered off. The biosensor is comprised of a three-dimensional interdigitated microelectrode (3D IMEs) with much higher aspect ratios than conventional IMEs and a hydrogel with a 3D mesh structure. The hydrogel increases the number of antibodies in the reaction region of the 3D IMEs by approximately 1,000-fold and enhances the impedance change induced by the specific binding of biomolecules. The hydrogel density is altered according to the target biomolecules. The impedance change by Aβ₄₂ binding was maximized to approximately 12.135 ± 0.903% in the 3D IMEs with a ‘dense’ hydrogel. The change by prostate-specific antigen (PSA) binding was maximized in the 3D IMEs with a ‘loose’ hydrogel. Thus, the dynamic range and sensitivity for detecting Aβ₄₂ were enhanced by a maximum of two orders and by approximately 2.58-fold compared to planar IMEs. These results demonstrate the high performance of the hydrogel-embedded 3D IMEs and its applicability for biological fluid-based diagnosis.