Chien-Ying Tsai

Room Temperature Operation of a Coulomb Blockade Sensor Fabricated by Self-Assembled Gold Nanoparticles using Deoxyribonucleic Acid Hybridization

Molecules of 3-mercaptopropyltrimethoxysilane react with gold nanoparticles to form a gold monolayer on a silicon dioxide substrate. The 12-mer capture Deoxyribonucleic acid (DNA) self-assembles with the nanometer-sized gold particles. Prior to DNA hybridization, a capture DNA produced via hybridization of the target and probe oligonucleotides is covalently bonded to the gold particles. In addition, the probe oligonucleotide containing a thiol group can self-assemble with additional gold nanoparticles, and multilayered structures are thereby fabricated. The device, assembled only with gold nanoparticles and without DNA immobilization, has no quantum effect conductivity, while a DNA sensor assembled from 4 nm gold nanoparticles and oligonucleotides exhibits Coulomb blockade. The measurement of the tunneling current as a function of applied voltage for the Coulomb blockade DNA sensor is reproducible. Using 14 nm gold nanoparticles instead, the Coulomb blockade for the DNA sensor only occurs at temperatures below 150 K.

A CMOS Biochip for Electrical Detection of DNA with an Embedded Current Amplifier Circuit

This paper presents a CMOS biochip for DNA detection with an embedded current amplifier circuit by using self-assembly multilayer gold nanoparticles (AuNPs). The biochip is fabricated by a TSMC 0.35 mum 2P4M standard CMOS process and post-CMOS micromachining processes. On each measuring spot, there is a pair of electrodes with a gap distance of 350 nm. Through a self-assembly process between suspended gold nanoparticles and the thiol-modified end of probe oligonucleotide strand, multilayer AuNPs on the nanogap surface can be established. An approximate 1000-fold increase in electric current between the nanogap of multilayer AuNPs over monolayer AuNPs is an indication of the presence of target oligonucleotide strand. After integrating the electrodes with an embedded current amplifier, the electric current of multilayer AuNPs can be amplified to the level of 1 mA and it is easily measured by a commercial Volt-ohm-Milliammeter without any expensive and complex instruments