"Coating the cantilever arrays with functional sensor layers is the key to converting the micromechanical structure into nanomechanical sensors," Alexander Bietsch of the University of Basel told nanotechweb.org. "However, standard microfabrication technology using photolithography is difficult to apply on cantilever sensors. Inkjet printing is the most promising technology for functionalization because it is fast, versatile and suitable for large-scale integration."

Bietsch and colleagues claim to have proved that the inkjet technique is suitable for one-sided deposition of many functional sensor layers, such as polymers from solution, self-assembled monolayers and DNA oligomers.

The team deposited self-assembled monolayers of alkanethiols onto gold-coated cantilevers in order to sensitize them to ion concentrations or pH in liquids. Attaching thiol-linked single-stranded DNA oligomers, meanwhile, enabled the gold-coated beams to detect gene fragments.

"A remarkable finding was that chemical surface reactions that need several minutes in macroscopic solutions take place even more efficiently in tiny printed droplets that evaporated within a few seconds," said Bietsch. "This effect enables inkjet printing as a rapid process for the formation of self-assembled monolayers and DNA oligomer layers."

The scientists also made a chemical gas sensor that used eight cantilevers, each coated with a different polymer.

Nanomechanical cantilever sensors could have applications in genomics, proteomics, medical diagnostics, gas sensing, process control, environmental monitoring and the detection of explosives.

The researchers reported their work in Nanotechnology.