title: Low-cost gas sensors produced by the graphite line-patterning technique applied to monitoring banana ripeness.
abstract: A low-cost sensor array system for banana ripeness monitoring is presented. The sensors are constructed by employing a graphite line-patterning technique (LPT) to print interdigitated graphite electrodes on tracing paper and then coating the printed area with a thin film of polyaniline (PANI) by in-situ polymerization as the gas-sensitive layer. The PANI layers were used for the detection of volatile organic compounds (VOCs), including ethylene, emitted during ripening. The influence of the various acid dopants, hydrochloric acid (HCl), methanesulfonic acid (MSA), p-toluenesulfonic acid (TSA) and camphorsulfonic acid (CSA), on the electrical properties of the thin film of PANI adsorbed on the electrodes was also studied. The extent of doping of the films was investigated by UV-Vis absorption spectroscopy and tests showed that the type of dopant plays an important role in the performance of these low-cost sensors. The array of three sensors, without the PANI-HCl sensor, was able to produce a distinct pattern of signals, taken as a signature (fingerprint) that can be used to characterize bananas ripeness.
authors.affiliation: National Nanotechnology Laboratory for Agribusiness (LNNA), Embrapa Instrumentation, São Carlos, SP, Brazil. alexandra@cnpdia.embrapa.br
authors.forename: Alexandra
authors.initials: A
authors.lastname: Manzoli
authors.forename: Clarice
authors.initials: C
authors.lastname: Steffens
authors.forename: Rafaella T
authors.initials: RT
authors.lastname: Paschoalin
authors.forename: Alessandra A
authors.initials: AA
authors.lastname: Correa
authors.forename: William F
authors.initials: WF
authors.lastname: Alves
authors.forename: Fábio L
authors.initials: FL
authors.lastname: Leite
authors.forename: Paulo S P
authors.initials: PS
authors.lastname: Herrmann
mesh_terms: D000042:Absorption; D000814:Aniline Compounds / Q000032:analysis; D001557:Benzenesulfonates / Q000032:analysis; D002164:Camphor / Q000032:analysis; D004867:Equipment Design; D005030:Ethylenes / Q000032:analysis; D005638:Fruit; D005740:Gases; D006108:Graphite / Q000032:analysis*; D008698:Mesylates / Q000032:analysis; D028521:Musa; D011108:Polymers / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013451:Sulfonic Acids / Q000032:analysis
chemical_list: D000814:Aniline Compounds; D001557:Benzenesulfonates; D005030:Ethylenes; D005740:Gases; D008698:Mesylates; D011108:Polymers; D013451:Sulfonic Acids; C416807:polyaniline; C045880:methanesulfonic acid; D002164:Camphor; D006108:Graphite; C036216:ethylene; C029501:4-toluenesulfonic acid