Protein Based Localized Surface Plasmon Resonance Gas Sensing

We apply the localized surface plasrnon resonance （LSPR） of gold nanoparticles （GNPs） covalently coupled with cytochrorne c （cyt c） to create a nanobiosensor for detecting hydrogen sulfide （H2S） in the range of 15 lOOppb. Monolayer formation of GNPs on glass surface functionalized with 3-aminopropyltrirnethoxysilane （APTMS） is performed for fabricating a chip-based format of the optical transducer. By chemical introduction of short-chain thiol derivatives on cyt c protein shell via its lysine residues, a very fast self-assembled rnonolayer （SAM） of cyt c is formed on the GNPs. Significant shifts in the LSPR peak （△λLSPR） are observed by reacting H2S with cyt c. Results show a linear relationship between △λLSPR and H2S concentration. Furthermore, shifts in the LSPR peak are reversible and the peak positions return to their pre-exposure values once the H2S is removed. The experirnental results strongly indicate that the protein based LSPR chip can be successfully used as a simple, fast, sensitive and quantitative sensor for H2S detection.

Development of two-port surface acoustic wave resonator with Al/Au electrodes for gas sensing

Simple and efficient surface acoustic wave （SAW） two-port resonators with low insertion loss and high Q-values on ST-X quartz substrate using a corrosion-proof A1/Au-stripe electrode structure are developed for gas sensing. It was composed of two shorted grating reflectors and adjacent intedigital transducers （IDT）, and an active metal film in the cavity between the IDTs for the sensitive film coating. The devices are expected to provide good protection towards metal electrode for gas sensors application in chemically reactive environments. Excellent device performance as low insertion loss, high Q factor and single-mode are achieved by carefully selecting the metallic electrode thickness, cavity length and acoustic aperture. Prior to fabrication, the coupling of modes （COM） model was performed for device simulation to determine the optimal design parameters. The fabricated single-mode SAW resonator at operation frequency of 300 MHz range exhibits matched insertion loss of ~6.5 dB and loaded Q factor in the 3000 range. Using the fabricated resonator as the feedback element, a duaresonator-oscillator with excellent frequency stability （0.1 ppm） was developed and evaluated experimentally, and it is significant for performance improvement of SAW gas sensor.

Solution-phase synthesis of ordered mesoporous carbon as resonant-gravimetric sensing material for room-temperature H2S detection

H2S can cause multiple diseases and poses a great threat to human health.However,the precise detection of extremely toxic H2S at room temperature is still a great challenge.Here,a facile solvent evaporation induced aggregating assembly(EIAA)method has been applied for the production of ordered mesoporous carbon(OMCs)in an acidic THF/H2 O solution with high-molecular-weight poly(ethylene oxide)-b-polystyrene(PEO-b-PS)copolymers as the structure-directing agent,formaldehyde and resorcinol as carbon precursors.Along with the continuous evaporation of THF from the mixed solution,cylindrical micelles are formed in the solution and further assemble into highly ordered mesostructure.The obtained OMCs possesses a two-dimensional(2 D)hexagonal mesostructure with uniform and large pore diameter(~19.2 nm),high surface area(599 m2/g),and large pore volume(0.92 cm3/g).When being used as the resonant cantilever gas sensor for room-temperature H2S detection,the OMCs has delivered not only a superior gas sensing performance with ultrafast re s ponse(14 s)and recovery(21 s)even at low concentration(2 ppm)but also an excellent selectivity toward H2S among various common interfering gases.Moreover,the limit of detection is better than 0.2 ppm,indicating its potential application in environmental monitoring and health protection.