Advances in developing rapid, reliable and portable detection systems for alcohol

Development of portable, reliable, sensitive, simple, and inexpensive detection system for alcohol has been an instinctive demand not only in traditional brewing, pharmaceutical, food and clinical industries but also in rapidly growing alcohol based fuel industries. Highly sensitive, selective, and reliable alcohol detections are currently amenable typically through the sophisticated instrument based analyses confined mostly to the state-of-art analytical laboratory facilities. With the growing demand of rapid and reliable alcohol detection systems, an all-round attempt has been made over the past decade encompassing various disciplines from basic and engineering sciences. Of late, the research for developing small-scale portable alcohol detection system has been accelerated with the advent of emerging miniaturization techniques, advanced materials and sensing platforms such as lab-on-chip, lab-on-CD, lab-on-paper etc. With these new inter-disciplinary approaches along with the support from the parallel knowledge growth on rapid detection systems being pursued for various targets, the progress on translating the proof-of-concepts to commercially viable and environment friendly portable alcohol detection systems is gaining pace. Here, we summarize the progress made over the years on the alcohol detection systems, with a focus on recent advancement towards developing portable, simple and efficient alcohol sensors.

Fabrication of a sub-10 nm silicon nanowire based ethanol sensor using block copolymer lithography

This paper details the fabrication of ultrathin silicon nanowires (SiNWs) on a silicon-on-insulator (SOI) substrate as an electrode for the electro-oxidation and sensing of ethanol. The nanowire surfaces were prepared by a block copolymer (BCP) nanolithographic technique using low molecular weight symmetric poly(styrene)-block-poly(methyl methacrylate) (PS-b-PMMA) to create a nanopattern which was transferred to the substrate using plasma etching. The BCP orientation was controlled using a hydroxyl-terminated random polymer brush of poly(styrene)-random-poly(methyl methacrylate) (HO-PS-r-PMMA). TEM cross-sections of the resultant SiNWs indicate an anisotropic etch process with nanowires of sub-10 nm feature size. The SiNWs obtained by etching show high crystallinity and there is no evidence of defect inclusion or amorphous region production as a result of the pattern transfer process. The high density of SiNWs at the substrate surface allowed the fabrication of a sensor for cyclic voltammetric detection of ethanol. The sensor shows better sensitivity to ethanol and a faster response time compared to widely used polymer nanocomposite based sensors.