SS-DNA functionalized ultra-thin-film ALN Contour-mode Resonators with self-sustained oscillator for volatile organic chemical detection

This paper reports on the design and experimental verification of a new class of nanoscale gravimetric sensors based on ultra-thin-film AlN contour-mode resonant sensor (CMR-S) functionalized with ss-DNA and connected to a chip-based self-sustaining oscillator loop (fabricated in the ON semiconductor 0.5 ¿m CMOS process) for direct frequency read-out. The 220 MHz oscillator based on the ultra-thin AlN CMR-S exhibits an Allan Variance of ~20 Hz for 100 ms gate time. The sensor affinity for the adsorption of volatile organic chemicals such as 2,6 dinitroluene (DNT, a simulant for explosive vapors) is enhanced by functionalizing the top gold electrode of the device with a thiol-terminated single stranded DNA sequence (Thiol - 5' CTT CTG TCT TGA TGT TTG TCA AAC 3') enabling the detection of concentrations as low as 1.5 part per billion (ppb).