title: Sensitivity comparison of vapor trace detection of explosives based on chemo-mechanical sensing with optical detection and capacitive sensing with electronic detection.
abstract: The article offers a comparison of the sensitivities for vapour trace detection of Trinitrotoluene (TNT) explosives of two different sensor systems: a chemo-mechanical sensor based on chemically modified Atomic Force Microscope (AFM) cantilevers based on Micro Electro Mechanical System (MEMS) technology with optical detection (CMO), and a miniature system based on capacitive detection of chemically functionalized planar capacitors with interdigitated electrodes with a comb-like structure with electronic detection (CE). In both cases (either CMO or CE), the sensor surfaces are chemically functionalized with a layer of APhS (trimethoxyphenylsilane) molecules, which give the strongest sensor response for TNT. The construction and calibration of a vapour generator is also presented. The measurements of the sensor response to TNT are performed under equal conditions for both systems, and the results show that CE system with ultrasensitive electronics is far superior to optical detection using MEMS. Using CMO system, we can detect 300 molecules of TNT in 10(+12) molecules of N2 carrier gas, whereas the CE system can detect three molecules of TNT in 10(+12) molecules of carrier N2.
authors: Faculty for Electrical Engineering, University of Ljubljana, Tržaška 25, Ljubljana 1000, Slovenia. drago.strle@fe.uni-lj.si.
authors: Drago
authors: D
authors: Strle
authors: Faculty for Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, Ljubljana 1000, Slovenia. bogdan.stefane@fkkt.uni-lj.si.
authors: Bogdan
authors: B
authors: Štefane
authors: Institute Jozef Stefan, Jamova 39, Ljubljana 1000, Slovenia. erik.zupanic@ijs.si.
authors: Erik
authors: E
authors: Zupanič
authors: Faculty for Electrical Engineering, University of Ljubljana, Tržaška 25, Ljubljana 1000, Slovenia. mario.trifkovic@fe.uni-lj.si.
authors: Mario
authors: M
authors: Trifkovič
authors: Faculty for Electrical Engineering, University of Ljubljana, Tržaška 25, Ljubljana 1000, Slovenia. marijan.macek@fe.uni-lj.si.
authors: Marijan
authors: M
authors: Maček
authors: Faculty for Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, Ljubljana 1000, Slovenia. gregor.jaksa@ijs.si.
authors: Gregor
authors: G
authors: Jakša
authors: Institute Jozef Stefan, Jamova 39, Ljubljana 1000, Slovenia. ivan.kvasic@ijs.si.
authors: Ivan
authors: I
authors: Kvasič
authors: Institute Jozef Stefan, Jamova 39, Ljubljana 1000, Slovenia. igor.musevic@ijs.si.
authors: Igor
authors: I
authors: Muševič
mesh_terms: D001272:Atmosphere / Q000032:analysis / Q000737:chemistry*; D003217:Conductometry / Q000295:instrumentation*; D025802:Electric Capacitance; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D053834:Explosive Agents / Q000032:analysis*; D005740:Gases / Q000032:analysis*; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation*; D008832:Microchemistry / Q000295:instrumentation; D018625:Microscopy, Atomic Force / Q000295:instrumentation*; D014303:Trinitrotoluene / Q000032:analysis*
chemical_list: D053834:Explosive Agents; D005740:Gases; D014303:Trinitrotoluene