Towards a VOCS Sensing Array via Batch-Compatible Post-CMOS Thiol Functionalization on CMOS-MEMS Monolithic Resonators

This paper presents monolithically integrated CMOS-MEMS resonators, dip-cast functionalized with three self-assembled organothiols, to develop a VOC multi-sensor array for breath pattern recognition in non-invasive disease diagnosis. The mechanical structures were fabricated using a commercial <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.35-\mu \mathrm{m}$</tex> CMOS technology followed by an in-house post-CMOS process. The main novelty of this approach relies on adopting a fully batch-compatible self-assembly solution-cast functionalization in line with emerging technological trends for Lab-on-Chip CMOS-compatible devices. Organothiols provide wide design flexibility enabling the extension of this fabrication method to other functional groups with similar anchoring properties. Experimental results demonstrate cross-reactive sensing of acetone, ethanol, hexane and toluene, with unique dynamic and static imprint characteristics.