Tubular/helical architecture construction based on rolled-up AlN nanomembranes and resonance as optical microcavity

Aluminum nitride(AlN)has attracted a great amount of interest due to the fact that these group III–V semiconductors present direct band gap behavior and are compatible with current micro-electro-mechanical systems.In this work,three dimensional(3D)AlN architectures including tubes and helices were constructed by rolling up AlN nanomembranes grown on a silicon-on-insulator wafer via magnetron sputtering.The properties of the AlN membrane were characterized through transmission electron microscopy and X-ray diffraction.The thickness of AlN nanomembranes could be tuned via the RIE thinning method,and thus micro-tubes with different diameters were fabricated.The intrinsic strain in AlN membranes was investigated via micro-Raman spectroscopy,which agrees well with theory prediction.Whispering gallery mode was observed in AlN tubular optical microcavity in photoluminescence spectrum.A postprocess involving atomic layer deposition and R6G immersion were employed on as-fabricated AlN tubes to promote the Q-factor.The AlN tubular micro-resonators could offer a novel design route for Si-based integrated light sources.In addition,the rolled-up technology paves a new way for AlN 3D structure fabrication,which is promising for AlN application in MEMS and photonics fields.

Preparation of large,ultra-flexible and free-standing nanomembranes of metal oxide-polymer composite and their gas permeation properties

In this work,fabrication of free-standing nanomembranes of metal oxide(MO_(x))and polymers by simple spin-coating method is discussed.First,double-layer nanomembranes containing MO_(x) and epoxy resin of polyethyleneimine and poly[(o-cresyl glycidyl ether)-co-formaldehyde]were prepared.Free-standing nanomembranes were successfully prepared,but defects formed in the metal oxide nanolayer during sharp bending of the nanomembrane.To overcome fragility of MO_(x) nanolayer,poly(vinyl alcohol)nanolayers were introduced between MO_(x) nanolayers by layer-by-layer(LbL)assembly process.The LbL nanomembrane was also free-standing and was highly flexible during macroscopic membrane manipulations.Even after transfer of the LbL nanomembrane onto a porous support,it did not have apparent cracks,confirmed by scanning electron microscopy(SEM).The LbL nanomembrane sustained low gas permeance,confirming the absence of significant defects,although it shows excellent flexibility.We believe that the presented LbL nanomembrane could be a platform useful for the design of molecular nanochannels,which is the next challenge for efficient gas separation.

The Use of Exoskeletons of Shrimp(Litopenaeus vanammei)and Crab(Ucides cordatus)for the Extraction of Chitosan and Production of Nanomembrane

Chitin is widely distributed in nature, being the main structural component of the exoskeleton of crustaceans and is non-toxic, biodegradable and biocompatible. These exoskeletons once discarded become an industrial waste creating environmental pollutant. In order to find an alternative use, the present work exploits the extraction of the chitosan from chitin that is present in the exoskeletons of shrimps Litopenaeus vannamei and crabs Ucides cordatus and transforms it into high valued products, which can help solving the environmental problem as well to provide extra income to the fishermen. One example is the manufacture of nanomembranes from chitosan for the application in medical textiles. Nanomembranes using electrospinning of chitosan solutions (7% and 5wt%) with 100:0 v/v (TFA/DCM) and 70:30 v/v (TFA/DCM) were produced. Morphological properties of chitin and chitosan were studied using SEM, DRX, and thermal properties through TG/DTG and molecular structure by FTIR analysis. TG/DTG showed thermal decomposition of chitosan samples. X-ray diffraction analysis indicated the semi-crystalline structure of chitosan, and highly crystalline structure for chitin. Morphologies of the nanomembranes were also observed from scanning electron micrographs. Results showed that the nanomembranes with 5% chitosan solutions with 70:30 v/v (TFA/DCM) showed facilitation in the formation of the nanomembranes. The nanomembranes of shrimp and crab with 5% 70:30 v/v (TFA/DCM) had higher breaking tension and breaking extension. With positive results obtained, the present work will help the authorities to organize the fishermen to have consciousness in the collection of exoskeleton waste as well as helping to have a better environment.

Laser-induced forward transferred silver nanomembrane with controllable light absorption

Laser processing provides highly-controlled modification and on-demand fabrication of plasmon metal nanostructures for light absorption and photothermal convention.We present the laser-induced forward tansfer(LIFT)fabrication of silver nanomembranes in control of light absorption.By varying the hatch distance,different morphologies of randomly distributed plasmon silver nanostructures were produced,leading to well-controlled light absorption levels from 11%to 81%over broadband.The anti-reflection features were maintained below 17%.Equilibrated and plain absorptions were obtained throughout all absorption levels with a maximum intensity fluctuation of±8.5%for the 225μJ cases.The 45μJ pulse energy can offer a highly equilibrated absorption at a 60%absorption level with an intensity fluctuation of±1%.Pattern transfer was also achieved on a thin tape surface.The laser-transferred characters and patterns demonstrate a localized temperature rise.A rapid temperature rising of roughly 15℃can be achieved within 1 s.The LIFT process is highly efficiently fabricated with a typical speed value of 10^(3)to 10^(5)cm^(2)/h.The results indicated that LIFT is a well-controlled and efficient method for the production of optical films with specific absorption levels.

Assessing bioactivity of environmental water samples filtered using nanomembrane technology and mammalian cell lines

This project reports on the use of a novel nanomembrane filtering technology to isolate and analyze the bioactivity of microplastic(MP)-containing debris from Lake Ontario water samples.Environmental MPs are a complex mixture of polymers and sorbed chemicals that are persistent and can exhibit a wide range of toxic effects.Since human exposure to MPs is unavoidable,it is necessary to characterize their bioactivity to assess potential health risks.This work seeks to quantify MP presence in the nearshore waters of Lake Ontario and begin to characterize the bioactivity of the filtrate containing MPs.We utilized silicon nitride(SiN)nanomembrane technology to isolate debris sized between 8 and 20μm from lake water samples collected at various times and locations.MPs were identified with Nile red staining.Cell-based assays were conducted directly on the filtered debris to test for cell viability,aryl hydrocarbon receptor(AhR)activity,and interleukin 6(IL-6)levels as a measure of proinflammatory response.All samples contained MPs.None of the isolated debris impacted cell viability.However,AhR activity and IL-6 levels varied over time.Additionally,no associations were observed between the amount of plastic and bioactivity.Observed differences in activity are likely due to variations in the physiochemical properties of debris between samples.Our results highlight the need for increased sampling to fully characterize the bioactivity of MPs in human cells and to elucidate the role that sample physiochemical and spatiotemporal properties play in this activity.

Artificial neuron synapse transistor based on silicon nanomembrane on plastic substrate

Silicon nanomembrane（SiNM）transistors gated by chitosan membrane were fabricated on plastic substrate to mimic synapse behaviors.The device has both a bottom proton gate（BG）and multiple side gates（SG）.Electrical transfer properties of BG show hysteresis curves different from those of typical SiO2 gate dielectric.Synaptic behaviors and functions by linear accumulation and release of protons have been mimicked on this device：excitatory post-synaptic current（EPSC）and paired pulse facilitation behavior of biological synapses were mimicked and the paired-pulse facilitation index could be effectively tuned by the spike interval applied on the BG.Synaptic behaviors and functions,including short-term memory and long-term memory,were also experimentally demonstrated in BG mode.Meanwhile,spiking logic operation and logic modulation were realized in SG mode.

Epidermal radio frequency electronics for wireless power transfer

Epidermal electronic systems feature physical properties that approximate those of the skin,to enable intimate,long-lived skin interfaces for physiological measurements,human–machine interfaces and other applications that cannot be addressed by wearable hardware that is commercially available today.A primary challenge is power supply;the physical bulk,large mass and high mechanical modulus associated with conventional battery technologies can hinder efforts to achieve epidermal characteristics,and near-field power transfer schemes offer only a limited operating distance.Here we introduce an epidermal,farfield radio frequency(RF)power harvester built using a modularized collection of ultrathin antennas,rectifiers and voltage doublers.These components,separately fabricated and tested,can be integrated together via methods involving soft contact lamination.Systematic studies of the individual components and the overall performance in various dielectric environments highlight the key operational features of these systems and strategies for their optimization.The results suggest robust capabilities for battery-free RF power,with relevance to many emerging epidermal technologies.

Foldable-circuit-enabled miniaturized multifunctional sensor for smart digital dust

Smart dust,which refers to miniaturized,multifunctional sensor motes,would open up data acquisition opportunities for Internet of Things(IoT)and Environmental protection applications.However,critical obstacles remain challenging in the integration of high-density sensors,further miniaturization of device platforms,and reduction of cost.Here,we demonstrate the concept of smart digital dust to address these problems,the results of which combine the benefit of(i)maturity of complementary metal-oxide semiconductor(CMOS)processing approaches and(ii)unique form factors of emerging flex-ible electronics.As a prototype for smart digital dust,we present a millimeter-scale multifunctional optoelectronic sensor platform con-sisting of high-performance optoelectronic sensor cores and commer-cially available integrated-circuit components.The smart material-assisted optoelectronic sensing mechanism enables real-time,high-sensitivity hydrogen,temperature,and relative humidity(RH)sens-ing based on a single chip with ultralow power consumption.Such a microsystem presented here introduces a viable solution to the multi-functional sensing need of IoT and could serve as a building block for the rapidly evolving future framework of smart dust.

High-finesse Fabry-Perot cavities with bidimensional Si_(3)N_(4) photonic-crystal slabs

Light scattering by a two-dimensional photonic-crystal slab(PCS)can result in marked interference effects associated with Fano resonances.Such devices offer appealing alternatives to distributed Bragg reflectors and filters for various applications,such as optical wavelength and polarization filters,reflectors,semiconductor lasers,photodetectors,bio-sensors and non-linear optical components.Suspended PCS also have natural applications in the field of optomechanics,where the mechanical modes of a suspended slab interact via radiation pressure with the optical field of a high-finesse cavity.The reflectivity and transmission properties of a defect-free suspended PCS around normal incidence can be used to couple out-of-plane mechanical modes to an optical field by integrating it in a free-space cavity.Here we demonstrate the successful implementation of a PCS reflector on a high-tensile stress Si_(3)N_(4) nanomembrane.We illustrate the physical process underlying the high reflectivity by measuring the photonic-crystal band diagram.Moreover,we introduce a clear theoretical description of the membrane scattering properties in the presence of optical losses.By embedding the PCS inside a high-finesse cavity,we fully characterize its optical properties.The spectrally,angular-and polarization-resolved measurements demonstrate the wide tunability of the membrane’s reflectivity,from nearly 0 to 99.9470±0.0025%,and show that material absorption is not the main source of optical loss.Moreover,the cavity storage time demonstrated in this work exceeds the mechanical period of low-order mechanical drum modes.This so-called resolved-sideband condition is a prerequisite to achieve quantum control of the mechanical resonator with light.