Rapid functionalization of cantilever array sensors by inkjet printing

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The controlled deposition of functional layers is the key to converting nanomechanical cantilevers into chemical or biochemical sensors. Here, we introduce inkjet printing as a rapid and general method to coat cantilever arrays efficiently with various sensor layers. Self-assembled monolayers of alkanethiols were deposited on selected Au-coated cantilevers and rendered them sensitive to ion concentrations or pH in liquids. The detection of gene fragments was achieved with cantilever sensors coated with thiol-linked single-stranded DNA oligomers on Au. A selective etch protocol proved the uniformity of the monolayer coatings at a microscopic level. A chemical gas sensor was fabricated by printing thin layers of different polymers from dilute solutions onto cantilevers. The inkjet method is easy to use, faster and more versatile than coating via microcapillaries or the use of pipettes. In addition, it is scalable to large arrays and can coat arbitrary structures in non-contact.