Microfabricated Alumina Nano Pore Membranes used for Impedance Sensing of DNA Immobilization and Hybridization

Congratulations to Dr. Songmei Wu from LMIS-1 and LMIS-4 who has published a new scientific paper in the field of Impedance sensing of DNA immobilization and hybridization by means of microfabricated alumina nano pore membranes.

In this work we demonstrate microfabricated thin alumina nanopore membranes as a platform for impedance sensing of DNA immobilization and hybridization. We develop a wafer-scale fabrication of free-standing alumina nanopore membranes with well controlled thickness, pore diameter and overall pore density. One 1 cm × 1 cm single chip contains an array of 69 membranes. Each membrane is 100 um × 100 um large and 2 um thick, with pore diameter of 120 nm. With low pore density of ∼6 pores/um 2 , nanopore resistance and membrane capacitance can be recognized clearly in the electrochemical impedance spectrum from 100 to 1 MHz. The total surface area can be further increased by the coating of silica nanoparticles with ∼20 nm in diameter. During the immobilization of probe ssDNA to (3-glycidoxypropyl) trimethoxysilane functionalized surface, the nanopore resistance drops significantly by 80%, whereas the membrane capacitance increases less than 2%. After hybridization with complementary DNA, the nanopore resistance increases up to 10%. Non-complementary ssDNA has no obvious effect. The detection limit is 12.5 nM in phosphate-buffered saline (PBS) solution.