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In this paper we report an acid-modulated strategy for novel peptide microarray production on biosensor interfaces. We initially selected a controlled pore glass (CPG) as a support for solid-phase peptide synthesis (SPPS) to implement a chemistry that can be performed at the interface of multiple field effect transistor (FET) sensors, eventually to generate label-free peptide microarrays for protein screening. Our chemistry uses a temporary protection of the N-terminal amino function of each amino acid building block with a tert-butyloxycarbonyl (Boc) group that can be removed after each SPPS cycle, in combination with semi-permanent protection of the side chains of trifunctional amino acid residues. Such a protection scheme with a well-proven record of application in conventional, batchwise SPPS has been fine-tuned for optimal performance on CPG and, from there, translated to SPR chips that allow layer-by-layer monitoring of amino acid coupling. Our results validate this acid-modulated synthesis as a feasible approach for producing peptides in high yields and purity on flat glass surfaces, such as those in bio-FETs.

Zinc oxide rod structures are synthetized and subsequently modified with Au, Fe2O3, or Cu2O to form nanoscale interfaces at the rod surface. X-ray photoelectron spectroscopy corroborates the presence of Fe in the form of oxide-Fe2O3; Cu in the form of two oxides-CuO and Cu2O, with the major presence of Cu2O; and Au in three oxidation states-Au3+, Au+, and Au-0, with the content of metallic Au being the highest among the other states. These structures are tested towards nitrogen dioxide, ethanol, acetone, carbon monoxide, and toluene, finding a remarkable increase in the response and sensitivity of the Au-modified ZnO films, especially towards nitrogen dioxide and ethanol. The results for the Au-modified ZnO films report about 47 times higher response to 10 ppm of nitrogen dioxide as compared to the non-modified structures with a sensitivity of 39.96% ppm(-1) and a limit of detection of 26 ppb to this gas. These results are attributed to the cumulative effects of several factors, such as the presence of oxygen vacancies, the gas-sensing mechanism influenced by the nano-interfaces formed between ZnO and Au, and the catalytic nature of the Au nanoparticles.

The sensing properties of (3-aminopropyl)triethoxysilane modified tungsten oxide nanowires (APTES@WO3-x) based sensors towards several gases and vapors are reported in this work. The developed sensors show high sensitivity to ethanol and nitrogen dioxide under UV-irradiation at room temperature (24 °C). Gas sensing results demonstrate enhanced sensing properties for the APTES@WO3-x compared to non-modified WO3-x sensors, with the APTES@WO3-x sensors showing approximately 17 and 20 times more sensitivity to ethanol and nitrogen dioxide, respectively, compared to the non-modified WO3-x sensors. The APTES@WO3-x sensors also display improved selectivity to nitrogen dioxide (oxidizing gas) and ethanol (among other reducing gases including acetone, toluene, hydrogen, and carbon monoxide). These results are attributed to the presence of the reactive amino group at the APTES@WO3-x sensors, which facilitates the chemical interaction with nitrogen dioxide and ethanol and the electron transfer towards/from WO3-x under UV-light excitation.

Gas microsensors based on zinc oxide structures with rod- and needle-like morphology, both integrated via a non-catalyzed vapor-solid mechanism enabled using aerosol-assisted chemical vapor deposition, are developed. Analyses of the films via SEM, TEM, XPS, and water contact angle indicate a higher concentration of oxygen vacancies, higher aspect ratio and higher roughness factor for the needles than for the rods. Gas sensing tests towards hydrogen and carbon monoxide demonstrate reduced humidity-interference, and higher responses to the analytes for the needle-based systems compared to the rods. These results are attributed to the morphology of the sensitive materials, which not only affects the surface-area-to-volume-ratio of the films but also their surface chemistry. These findings indicate that a thorough optimization of morphology, structure and surface properties of gas sensitive metal oxides could allow for more reliable sensor operation in humid conditions.

Chemoresistive gas microsensors with highly hydrogen sensitive zinc oxide rods dominated by exposed {100} surfaces are fabricated. The hexagonal rod structures are integrated into micromachined transducing platforms without the need for substrate pre-treatment, via a vapor-solid mechanism enabled using an aerosol-assisted chemical vapor deposition method. The microsensors demonstrate an enhanced functionality towards hydrogen, with greater sensor responses (between 200% and 1800%) compared to other gases including ethanol, carbon monoxide, acetone, and toluene, and with low interferences among these reductive gases. The improved functionality of these systems towards hydrogen is attributed to the formation of an accumulation layer at the zinc oxide rods after hydrogen exposure, which includes a mechanism not only dominated by the oxygen vacancies, but also by the formation of intermediate energy levels for the transfer of charge from hydrogen to the zinc oxide conduction band.

Gas microsensors based on ZnO structures grown via aerosol-assisted chemical vapor deposition are fabricated. The photoactivated and thermoactivated gas sensing properties of these systems toward CO are presented. Results demonstrate photoactivated responses at room temperature with improved characteristics, which include 35 % higher response and 7% faster response times, compared to the thermoactivated response of the sensors at 250 °C. This characteristic becomes significantly advantageous as it allows for the sensor to operate without integrated heaters minimizing the power consumption of the system.

This paper reports and discusses the design and ground tests of a CubeSat payload which allows to measure, in-situ and in real time, the degradation of a polymer of electronic interest due to atomic oxygen etching in LEO. It provides real-time information on how the degradation occurs, eliminating the need to work with samples recovered once the mission has finished. The polymer, TIPS-Pentacene, is deposited on the surface of a microelectromechanical (MEMS) cantilever, which works as a resonator embedded in a Pulsed Digital Oscillator circuit. The mass losses in the polymer due to atomic oxygen corrosion produce variations in the resonant frequency of the MEMS, which is continuously sensed by the circuit and transmitted to the ground. This way, polymer mass losses around 10-12 kg can be detected during the mission. The payload is a part of the 3Cat-1 mission, a nano-satellite aimed at carrying out several scientific experiments., Peer Reviewed, Postprint (author's final draft)

The aerosol assisted chemical vapor deposition of Fe2O3 nanoparticle-tunctionalized tungsten oxide nanoneedles and their gas sensing properties are presented here. Material analysis demonstrates the incorporation of 4 to 15 nm Fe2O3 nanoparticles at the surface of the tungsten oxide nanoneedles. Gas sensing tests show improved tungsten oxide sensitivity, to toluene, ethanol and hydrogen, with the highest sensitivity (six-fold) to toluene, due to its fonctionalization with Fe2O3. This enhancement is nearly similar to the enhancement obtained when fonctionalizing tungsten oxide with platinum, suggesting that the sensing performance of tungsten oxide could be improved to a same extent using second-phase nanoparticles of metal oxides, which are less expensive and more abundant than precious metals such as Pt., Zde jsou prezentovány depozice chemickými výpary s pomocí aerosolu na výrobu nanojehel z oxidu wolframu funkciolizované nanočásticemi oxidu železitého a jejich schopnost detekce plynu. Analýza materiálu dokazuje začlenění 4 až 15 nm nanočástic Fe2O3 na povrchu nanojehel oxidu wolframu. Testy detekce plynu ukazují zlepšenou citlivost oxidu wolframu na toluen , ethanol a vodík , s nejvyšší citlivostí ( šestinásobnou ) na toluenu , v důsledku jeho funkcionalizace s Fe2O3. Toto zvýšení je podobné u oxidu wolframu funcionalizovaného platinou , což naznačuje, že detekční schopnost oxidu wolframu lze dále zlepšit za použití nanočástice oxidů kovů , které jsou méně nákladné a hojnější než drahé kovy jako například Pt.