photo: DNA
The researchers performed experiments
with pieces of DNA; © SXC

The nanopore sensor, made by drilling a tiny hole through a thin film of aluminum oxide, could ultimately prove capable of performing DNA analysis with a single molecule, offering tremendous possibilities for personalized medicine and advanced diagnostics.

"Solid-state nanopore sensors have shown superior chemical, thermal and mechanical stability over their biological counterparts, and can be fabricated using conventional semiconductor processes," said Rashid Bashir, a Bliss Professor of electrical and computer engineering and bioengineering, and the director of the university's Micro and Nanotechnology Laboratory.

"The aluminum-oxide nanopore sensors go a step further," Bashir said, "exhibiting superior mechanical properties, enhanced noise performance and increased lifetime over their silicon-oxide and silicon-nitride counterparts."

To make the sensor, the researchers begin by using a technique called atomic layer deposition to produce a very thin film of aluminum oxide on a silicon substrate.

Next, the central portion of the substrate is etched away, leaving the film as a suspended membrane. An electron beam is then used to create a very tiny hole – a nanopore – in the membrane.

The nanopore sensors had pore diameters ranging in size from 4 to 16 nanometers, and a film thickness of approximately 50 nanometers. Thinner membranes are possible with atomic layer deposition, Bashir said, and would offer higher resolution of the detection.

To demonstrate the functionality of the aluminum-oxide nanopores, the researchers performed experiments with pieces of DNA containing approximately 5,000 base pairs. Bashir's team verified the detection of single molecules, with a signal-to-noise performance comparable to that achieved with other solid-state nanopore technology.; Source: University of Illinois