Tin oxide nanosensor fabrication using AC dielectrophoretic manipulation of nanobelts

Nanobelts are a new class of semiconducting metal oxide nanowires. The ribbon-like nanobelts are chemically pure and structurally uniform single crystals, with clean, sharp, smooth surfaces, and rectangular cross-sections. Positive and negative dielectrophoresis (DEP) was demonstrated for the first time on semiconducting oxide nanobelts. This effect was then used for the fabrication of a nanodevice, which consisted of SnO₂ nanobelts attached to castellated gold electrodes defined on a glass substrate, and covered by a microchannel. The SnO₂ nanobelts (width ∼ 100-300 nm, thickness ∼ 30-40 nm) were suspended in ethanol and introduced into the microchannel. An alternating (AC) voltage of ∼9.8 V peak to peak, with variable frequency, was applied between the electrodes (minimum electrode gap ∼ 20 μm), which corresponds to an average electric field strength of less than 2.5 × 10⁵ V/m. In the 10 Hz-1 kHz range, repulsion between the nanobelts and the electrodes occurred, while in the 1-10 MHz range, attraction was observed. Once the nanobelts touched the electrodes, those that were sufficiently long bridged the electrode gaps. The device was characterized and can potentially be used as a nanosensor.     

纳米技术——传感器发展的新契机

纳米技术给传感器的发展提供了新的机遇。讨论了纳米技术和纳米传感器对未来社会的巨大影响以及其潜在的、令人鼓舞的发展前景。     

A novel graphene-like titanium carbide MXene/Au–Ag nanoshuttles bifunctional nanosensor for electrochemical and SERS intelligent analysis of ultra-trace carbendazim coupled with machine learning

A new bifunctional intelligent nanosensing platform based on graphene-like titanium carbide MXene (Ti₂C MXene)/Au–Ag nanoshuttles (NSs) for both electrochemical and surface-enhanced Raman scattering (SERS) intelligent analysis of ultra-trace carbendazim (CBZ) residues in tea and rice coupled with machine learning (ML) was successfully designed. Ti₂C MXene was synthesized by selectively etching Al layers of Ti₂AlC with hydrofluoric acid and high-temperature calcination. Ti₂C MXene/Au–Ag NSs prepared by the ultrasonic dispersion of graphene-like Ti₂C MXene into Au–Ag NSs solution under dark conditions displayed large and rough surface, enhanced conductivity, excellent electrochemical response, prominent Raman enhancement, and high stability. The ML via different algorithms such as artificial neural network, support vector machine, and relevance vector machine (RVM) for the intelligent analysis of CBZ was contrasted and discussed. RVM displayed more superiority for the electrochemical analysis of CBZ in a wide linear range of 0.006 – 9.8 μM with low limit of detection (LOD) of 0.002 μM and SERS detection of CBZ in the wide linear range of 0.033 – 10 μM with low LOD of 0.01 μM. This will provide a new bifunctional intelligent sensing platform via different ML algorithms for improving accuracy of sensor via mutual verification of two or more methods of detection and a new bifunctional nanosensing platform based on the development of graphene-like nanohybrid for food and agro-products safety.     

微型传感器及纳米传感器

综述了微型传感器及纳米传感器的发展现状，叙述了微型传感器技术的发展趋势及其关键技术，并介绍了微型传感器技术在军事领域中的应用情况。     

Properties of a single SnO2:Zn2SnO4 – Functionalized nanowire based nanosensor

Tin oxide nanowires (SnO₂ NWs) exhibit large potential for applications in sensor and detector technology. Using a flame transport synthesis method, high-quality single crystalline SnO₂ nanowires (NWs) with Zn₂SnO₄ dots functionalized surface were synthesized on a large scale. The individual SnO₂:Zn₂SnO₄ nanowire based ultraviolet photodetector and ethanol vapors nanosensors were fabricated by contacting an individual nanowire to pre-patterned Au electrodes via a FIB/SEM system. The photodetector structure exhibited excellent photoconductive performance in terms of high response to the 375 nm ultraviolet light irradiation, ultra-fast response and recovery time at different temperatures (25–300 K). It also showed a long term stability and reliability. The n-type semiconducting behavior of the SnO₂:Zn₂SnO₄, forms an excellent material for fabricating highly sensitive and rapid responding sensors, which will enable the development of high-performance multi-functional devices.     

ZeptoFarad capacitance detection with a miniaturized CMOS current front-end for nanoscale sensors

The experimental detection of capacitance variations with a resolution as low as few zeptoFarads (10⁻²¹ F) is presented. This is achieved by means of a CMOS ultra-low-noise and wide-bandwidth current sensing circuit, coupled to a lock-in amplifier to perform capacitance and conductance measurements in a frequency range from DC to 1 MHz. The adoption of an integrated implementation, based on an original circuital topology, provides miniaturization and performance improvement. The mm-sized chip can be easily integrated in extremely compact sensing setups. Resolution limits are analyzed in detail and experimentally investigated by means of a mechanical fixture that converts micrometric linear displacement into sub-aF capacitance steps. The experimental results match the theoretical expectation down to a resolution of 5 zF_rms (6 V at 100 kHz, with a 100 ms time constant). The achieved current resolution of 15 fA_rms (at ∼ms time scale) and the tracking of 40 zF capacitance steps demonstrate how the proposed read-out circuit can serve as a versatile tool for the development of nanosensors.     

IFE based nanosensor composed of UCNPs and Fe(Ⅱ)-phenanthroline for detection of hypochlorous acid and periodic acid

Oxidizing CIO^-and IO₄^-exist widely in environment and are closely related to the health of organisms.Accordingly,fast,sensitive,and direct detection of the two species is significant.Using IFE in UCNPs@PAA and Fe(Ⅱ)-phenanthroline system,an elegant ratiometric fluorescent nanosensor,without noble metal nanoparticle,was designed for the detection of CIO^-and IO₄^-.Fe(Ⅱ)-phenanthroline complex is used as fluorescent absorber,which can...