Electronic Nose Based on Multipatterns of ZnO Nanorods on a Quartz Resonator with Remote Electrodes

Abstract

An electrodeless monolithic multichannel quartz crystal microbalance (MQCM) sensor was developed via the direct growth of ZnO nanorod patterns of various sizes onto an electrodeless quartz crystal plate. The patterned ZnO nanorods acted as independent resonators with different frequencies upon exposure to an electric field. The added mass of ZnO nanostructures was found to significantly enhance the quality factor (QF) of the resonator in electrodeless QCM configuration. The QF increased with the length of the ZnO nanorods; ZnO nanorods 5 μm in length yielded a 7-fold higher QF compared to the QF of a quartz plate without ZnO nanorods. In addition, the ZnO nanorods offered enhanced sensitivity due to the enlarged sensing area. The developed sensor was used as an electronic nose for detection of vapor mixtures with impurities.

Polarity Index Dependence of M13 Bacteriophage-based Nanostructure for Structural Color-based Sensing

“…Innovative structures fabricated using M13 bacteriophage have been used to produce piezoelectric nanostructures, virusbased full-color pixels, and highly effective surface plasmon resonance (SPR) sensors [1][2][3][4][5][6][7][8][9][10]. Furthermore, in less than a decade, M13 bacteriophage-based color sensor systems have shown great potential for the detection of cancer cells and various target chemicals, such as TNT, antibiotics, and endocrine-disrupting chemicals (EDCs) [11][12][13][14][15][16][17][18][19].…”

Communication: Anti-icing characteristics of superhydrophobic surfaces investigated by quartz crystal microresonators

“…The resonance frequency of a quartz crystal is sensitive to changes in mass and viscous damping only in the vicinity of its surface (∼1 µm) because the acoustic wave decays rapidly with the distance from the surface, 27,28 which enables the sensitive evaluation of anti-icing performance. We synthesized anodic aluminum oxide (AAO) or ZnO nanorods directly onto gold-coated quartz crystal substrates and rendered their surfaces hydrophobic or superhydrophobic via chemical modifications with octyltrichlorosilane (OTS), octadecyltrichlorosilane (ODS), or octadecanethiol (ODT).…”

“…31 The temperature-dependent changes in the resonance frequency and Q-factor of the quartz crystal were monitored in situ by connecting the electrodes to a custom-built PC-based conductance measurement system. 28 The resonance frequencies and Q-factors were calculated from Lorentzian fits of the conductance spectra. The water contact angle of each nanostructure surface was measured by using a goniometer (SmartDrop, Femtofab, Korea) with a 2 µl water droplet.…”

Highly stable superhydrophobic surfaces under flow conditions

“…Most studies, however, have focused on the fabrication of superhydrophobic surfaces and only a few have reported their stability in water. [13][14][15][16] Lee and Yong used a video camera to investigate the influence of hydrostatic pressure on the stability of W 18 O 49 nanowire-grown superhydrophobic surfaces with various surface chemistries. 15 The total reflection of white light between the water layer and the air pockets produced images of silvery surfaces, and the numbers of white and black pixels was converted to the surface areas of the nonwetted and wetted regions of the surface, respectively.…”

“…The acoustic wave generated by a vibrating quartz crystal decays rapidly with the distance from the crystal surface, so the decay length is just $250 nm in water at room temperature, which means that the QCM is sensitive to changes in mass or viscous damping only near the surface (i.e., surface wetting). [17][18][19] We utilized this advantage of QCMs to investigate the influence of water flow rates on the stability of superhydrophobicity.…”