Nanoenabled microelectromechanical sensor for volatile organic chemical detection

Abstract

A nanoenabled gravimetric chemical sensor prototype based on the large scale integration of single-stranded DNA (ss-DNA) decorated single-walled carbon nanotubes (SWNTs) as nanofunctionalization layer for aluminum nitride contour-mode resonant microelectromechanical (MEM) gravimetric sensors has been demonstrated. The capability of two distinct single strands of DNA bound to SWNTs to enhance differently the adsorption of volatile organic compounds such as dinitroluene (simulant for explosive vapor) and dymethyl-methylphosphonate (simulant for nerve agent sarin) has been verified experimentally. Different levels of sensitivity (17.3 and 28 KHz μm2/fg) due to separate frequencies of operation (287 and 450 MHz) on the same die have also been shown to prove the large dynamic range of sensitivity attainable with the sensor. The adsorption process in the ss-DNA decorated SWNTs does not occur in the bulk of the material, but solely involves the surface, which permits to achieve 50% recovery in less than 29 s.

Nanoscaled piezoelectric aluminum nitride contour-mode resonant sensors

“…The use of CNTs as adhesion layer for the attachment of two strands of ss-DNA to CMR-S has been investigated [30,31] and has shown promising results in terms of selectivity. Currently, the direct attachment of the DNA strands to the top gold electrode of the resonator is being explored as a simpler and more manufacturable technique.…”

“…ss-DNA offers this capability since it practically forms a very thin (few nm) equivalent layer. Refresh times in the order of few 10s of seconds have been recorded [31] when the sensor is exposed to a flow of pure nitrogen. It is important to note that a fast refresh time is generally associated with a poor level of affinity to selected VOCs and a compromise between refresh speed and selectivity has to be made.…”

Ultra-thin-film AlN contour-mode resonators for sensing applications

“…High performance AlN Contour-Mode Resonant Sensors (CMR-S) with multiple frequencies of operation on the same chip and capable of detecting multiple VOCs have been previously demonstrated by our group [6]. In this work, the unique capability of CMR-S to decouple resonance frequency from mass sensitivity is investigated.…”

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

“…The capability of single stranded DNA to selectively enhance the adsorption of volatile organic compounds such as dymethyl-methylphosphonate (DMMP, a simulant for nerve agent sarin) and 2,6 dinitroluene (DNT, a simulant for explosive vapors) has been recently demonstrated by our group. Single wall carbon nanotube (SWNTs) directly grown on the top surface of a CMR-S [4] were functionalized by the DNA strands. In this work, in order to enhance the sensor affinity for the adsorption of volatile organic chemicals, the top gold electrode of the device was directly functionalized (without any SWNT interface layer) with a thiol-terminated ss-DNA sequence.…”

“…These issues have been recently overcome by AlN Contour-Mode Resonant Sensors (CMR-S) [4,5,6]. In fact, this technology enables the fabrication of ultra-sensitive nanoscaled devices that can be piezoelectrically actuated and sensed directly on chip [5].…”