Wide-range humidity sensing and monitoring applications including instrumentation, agriculture, meteorology, biomedicine, and food processing have attracted long-standing interests, where recently substantial progress is made in both sensing-material science and microfabrication technologies to achieve portable, reliable and low-cost humidity sensing instruments. Due to their high sensitivity, enormous miniaturization potential, and welldeveloped high-volume microfabrication technologies, microelectromechanical systems (MEMS)-based piezoresistive cantilever devices covered by large-surface-area nanostructures of hygroscopic materials offer an ideal platform for highly sensitive humidity detection.Since resonant gravimetric sensing is the dominant humidity sensing technique in recent research works, in this paper, resonant actuation principles for microcantilevers (i.e. the dynamic operation mode) are addressed and compared with respect to the quality of the amplitude and phase signals, as required for on-line frequency tracking using a phase-locked loop circuit. Parasitic feedthrough effects are considered between the resonance-mode (f 0 ) excitation element and the piezoresistive detection circuit, which can lead to a reduction of stop-band attenuation, the generation of a parallel resonance in close vicinity of f 0 , a hardly detectable 90° phase jump, and a long-term drift of resonance frequency and phase shift. Methods for eliminating these parasitic feedthrough effects have been considered, including de-embedding of the motional signal by later data processing and the integration of a reference cantilever or circuit.Then, different concepts of environmental sensing using microcantilevers are described, including detection of particulate matter and gas molecules/volatile organic compounds. Depending on the condition of the cantilever during sensing operation, two different modes have been used to sense the target analyte (i.e. static and dynamic modes). In a static operation mode, mass change of the cantilever, surface stress, or swelling of a layer on top related to the uptake and binding of particles or molecules on the cantilever are detectable via a deformation of the cantilever (i.e. by deflection or strain), which can be sensed by an integrated

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In this study, we investigate the performance of two piezoresistive micro-electro-mechanical system (MEMS)-based silicon cantilever sensors for measuring target analytes (i.e., ultrafine particulate matters). We use two different types of cantilevers with geometric dimensions of 1000 × 170 × 19.5 µm3 and 300 × 100 × 4 µm3, which refer to the 1st and 2nd types of cantilevers, respectively. For the first case, the cantilever is configured to detect the fundamental in-plane bending mode and is actuated using a resistive heater. Similarly, the second type of cantilever sensor is actuated using a meandering resistive heater (bimorph) and is designed for out-of-plane operation. We have successfully employed these two cantilevers to measure and monitor the changes of mass concentration of carbon nanoparticles in air, provided by atomizing suspensions of these nanoparticles into a sealed chamber, ranging from 0 to several tens of µg/m3 and oversize distributions from ~10 nm to ~350 nm. Here, we deploy both types of cantilever sensors and operate them simultaneously with a standard laboratory system (Fast Mobility Particle Sizer, FMPS, TSI 3091) as a reference.

It is currently uncertain to what extent genetic transformations of strategic crops (targeting diverse traits) have improved their N use efficiency (NUE), and what the key factors affecting their NUE are. Based on data collected from 130 publications, the effect sizes of genetic transformations and the key factors influencing NUE for three major cereal crops (rice, maize, and wheat), were investigated using a meta-analysis approach. Genetic transformations increased yield, shoot biomass, N uptake efficiency (NUpE), and partial factor productivity of N (PFPN) in the crops, but decreased shoot NUE (SNUE) and grain NUE (GNUE). Transporter genes improved yield and NUE parameters more efficiently, than did the other gene types. The effect sizes for some NUE parameters varied according to crop species and experimental conditions but did not differ between the overexpression and ectopic expression methods. Most effect sizes did not correlate with gene overexpression levels. These results indicate a promising potential of genetic transformations approaches for improving certain NUE parameters.

Organic−inorganic hybrids are ideal for gas detection, considering their selectivity and sensitivity to single gas species under moderate working conditions. However, the poor surface-to-volume ratio and low electron density of organic materials hinder their application in high-performance resistive gas sensors. Instead herein, a gravimetric sensor is realized on the basis of an in-plane self-actuating and self-reading piezoresistive microcantilever-chip (PMC), which is patterned with an (inorganic) 3D framework of ZnO nanorods on a Si-nanopillar array (3D ZnO-NRs@Si-NPLs) and functionalized by a thin (organic) self-assembled monolayer (SAM, (3-aminopropyl)trimethoxysilane (APTES)) for interacting with NO 2 . For stable adsorption/desorption rates of NO 2 , this SAM-on-3D ZnO-NRs@Si-NPL PMC (S3-PMC) was exposed to constant light illumination by an LED (wavelength: 530 nm, intensity: 10 mW/cm 2 ), realizing a limit of detection (LOD) of about 2 parts per billion by volume (ppbv) for NO 2 at room temperature, together with fast response and complete recovery within times of 42.1 ± 6.6 s and 112 ± 17.4 s, respectively, to NO 2 concentrations ranging up to 1000 ppbv. Moreover, the sensor shows reliable stability under both short-and long-time (31 days) exposure to NO 2 , where resonance frequency-shift deviations of merely at most ±5% and ±9%, respectively, are observed. These unprecedented results indicate an enormous potential of the S3-PMC for portable gas sensor arrays in high-resolution real-time-monitoring applications.