A Bio‐inspired Potassium and pH Responsive Double‐gated Nanochannel

Bio‐inspired nanochannels have emerged as an interface to mimic the functionalities of biological nanochannels. One remaining challenge is to develop double‐gated nanochannels with dual response, which can regulate the ion transport direction by alternately opening and closing the two gates. In this work, a bio‐inspired potassium and pH responsive double‐gated nanosystem is presented, constructed through immobilizing C‐quadruplex and G‐quadruplex DNA molecules onto the top and bottom tip side of a cigar‐shaped nanochannel, respectively. It is demonstrated that the two gates of the nanochannel can be opened and closed alternately/simultaneously. This phenomenon results from the attached DNA conformational transition caused by adjusting the concentrations of potassium ion and proton. This design is believed to be the first example of dual‐responsive double‐gated nanosystem, and paves a new way to investigate more intelligent bio‐inspired nanofluidic system.     

Ionic Diode Based on an Asymmetric-Shaped Carbon Black Nanoparticle Membrane

Bioinspired ionic diodes are widely explored to mimic the controllable ion transport of biological ion channels. However, due to their vertical structures, the integration of conventional ionic diodes into complex ionic circuits is still a challenge. Here, a horizontal ionic diode is developed based on an asymmetric nanochannel network membrane (NCNM) constructed from carbon black nanoparticles. The rectification of ionic current is achieved through the asymmetric concentration polarization of ions at two ends of the asymmetric NCNM. The rectification ratio of the NCNM ionic diode can be modified flexibly by changing the working fluid and the geometry of the NCNM. It is found that with the presence of cationic surfactant in the working fluid, the rectification ratio increases more than 30 times from 3.03 to 109.77. Advanced functions of the developed ionic component, including working as an ionic transistor for current switching and integrating into an ionic diode bridge on a single nanofluidic chip for rectifying alternating current signals, are also demonstrated in this paper. The horizontally arranged NCNM ionic diode possesses the advantages of easy fabrication and integration that can be practically applied in the development of ionic electronics and biocomputing.     

Multi-Control of Ion Transport in a Field-Effect Iontronic Device based on Sandwich-Structured Nanochannels

Biomimetic smart nanochannels can regulate ion transport behavior responsive to the external stimuli, having huge potential in nanofluidic devices, sensors and energy conversion. Field-effect nanofluidic diodes or transistors based on electric-responsive nanochannels are emerging owing to their advantages such as non-invasiveness, in situ, real time, and high efficiency. However, simultaneously realizing the voltage-control of the ion conductance and ion current rectification (ICR) properties is still a big challenge. Here, a field-effect iontronic device is developed based on ionomer/anodic aluminum oxide/conducting polymer sandwich-structured nanochannel to realize the multi-control of ion transport behaviors including ion conductance, ICR magnitude, and ICR direction by modulating the surface charge, wettability, and morphology of the nanochannel. The electroactive conducting polymer carries tunable surface charges responsive to the electric stimuli, leading to the regulation of ICR values. The complex three-segment structures lead to the reverse of ICR direction by reconfiguring the charge distribution along with the whole channel. The switching wettability between hydrophilic and hydrophobic results in the regulation of ion conductance. Furthermore, the field-effect iontronic device functions in a wide salinity range especially in hypersaline environment, due to the salinity-adaptive properties of the membrane. A new route is provided for designing more functional field-effect nanofluidic devices.     

Light‐Gating Titania/Alumina Heterogeneous Nanochannels with Regulatable Ion Rectification Characteristic

Bioinspired artificial nanochannels exhibiting ion transport properties similar to biological ion channels have been attracting some attention for biosensors, separation technologies, and nanofluidic diodes. Herein, an easily available artificial heterogeneous nanochannel shows both ion gating and ion rectification characteristics when irradiated by ultraviolet light. The fabrication of heterogeneous nanochannels includes the coating of an anatase TiO₂ porous layer on an alumina porous supporter, followed by a chemical modification with octadecyltrimethoxysilane (OTS) molecules. The irreversible decomposition of OTS molecules by TiO₂ photocatalysis under ultraviolet light results in a change of surface wettability and an asymmetric distribution of surface negative charges simultaneously, which contributes to the ion gating and ion rectification. The asymmetric distribution of negative charges in the TiO₂ porous layer can be controlled by the irradiation time of ultraviolet light, which regulates the ion rectification characteristic.     

Bioinspired Self‐Gating Nanofluidic Devices for Autonomous and Periodic Ion Transport and Cargo Release

The biochemical oscillatory reaction induced self‐gating process of biological ion channels is essential to life processes, characterized as autonomous, continuous, and periodic. However, few synthetic nanochannel systems can achieve such excellent self‐gating property. Their gating properties work greatly depending on the frequent addition of reactants or the supply of external stimuli. Herein, a novel bioinspired self‐gating nanofluidic device that can transport mass in a continuous and periodic manner is reported. This self‐gating device is constructed by using a fully closed‐system pH oscillator to control the gating processes of the artificial proton‐gated nanochannels. With cyclic oscillation of protons inside the nanochannel induced by the oscillatory chemical reactions of the pH oscillator, surface charge density and polarity of the nanochannels can be self‐regulated, resulting in an autonomous and periodic switching of the nanochannel conductance between high and low states as well as the selectivity between cation selective and anion selective states. Moreover, by using Rhodamine B and Ruthenium(II) compound as the cationic cargoes, periodic release of these charged molecules is also observed. Therefore, this work opens up a new avenue to build self‐gating nanofluidic devices, which may not only act as ion oscillators, but potentially find applications in controlled‐release fields as well.     

Surface Charge Modification on 2D Nanofluidic Membrane for Regulating Ion Transport

2D nanofluidic membranes are capable of regulating ion transport toward various applications concerning energy and environment, which is primarily contributed by the excess charge on the interior surface of narrow nanoscale pores. However, there is still a lack of comprehensive summaries and discussions on the surface charge modification principles and strategies of 2D nanofluidic membranes, as well as the practical applications of charge-modified 2D nanofluidic membranes for regulating ion transport. In this review, the surface charge modification principles and charge modification methods of 2D nanofluidic membranes are first introduced in detail, which is of great significance for improving the ion regulation capability of membranes and realizing the design of nanochannel materials. Next, recent advances in the two typical applications of concentration cells and water treatment based on charge-modified 2D nanofluidic membranes are summarized. Finally, some challenges and prospects related to charge-modified 2D nanofluidic membranes are discussed to indicate directions for future research in this field. It is anticipated that this review will provide valuable strategies for the development of high-performance charge-modified 2D nanofluidic membranes toward energy and environment applications.     

Optical Gating of Photosensitive Synthetic Ion Channels

4‐oxo‐4‐(pyren‐4‐ylmethoxy) butanoic acid is used as a photolabile protecting group to show the optical gating of nanofluidic devices based on synthetic ion channels. The inner surface of the channels is decorated with monolayers of photolabile hydrophobic molecules that can be removed by irradiation, which leads to the generation of hydrophilic groups. This process can be exploited in the UV‐light‐triggered permselective transport of ionic species in aqueous solution through the channels. The optical gating of a single conical nanochannel and multichannel polymeric membranes is characterised experimentally and theoretically by means of current–voltage and selective permeation measurements, respectively. It is anticipated that the integration of nanostructures into multifunctional devices is feasible and can readily find applications in light‐induced controlled release, sensing, and information processing.     

Single level integrated packaging modules for high performanceelectronic systems

In this paper, we studied a novel packaging scenario that aims to integrate or eliminate the existing multilevel packaging hierarchies toward single level integration. This new approach is an extension of VLSI technology where standard IC processes were pursued in the whole fabrication sequence. Main benefits include very high performance, ultra high density, mixed-signal integration, and inexpensive. Several key technologies such as chip assembly and planarization were developed. A feasible fabrication procedure for single level integration has been established. Demonstrating modules were presented. Interconnect structures, signal and power distribution, and electrical performance were studied theoretically and experimentally for GHz off-chip operating. Properties of signal propagation and coupling from chip to chip were investigated both in frequency domain and in time domain by simulations and by high frequency measurements. The studies show that the new modules are capable of several Gb/s/pin data rate for off-chip communications. Besides, some design guidelines for best performance are obtained through the work     

A Photon‐Fueled Gate‐Like Delivery System Using i‐Motif DNA Functionalized Mesoporous Silica Nanoparticles

A novel photon‐fueled gate‐like mesoporous silica nanoparticles (MSN)‐based delivery system is reported. In this system, the malachite green carbinol base (MGCB) is immobilized on the nanochannel wall of MSN as a light‐induced hydroxide ion emitter and i‐motif DNA is grafted on the surface of MSN as a cap. Photoirradiation with 365 nm wavelength UV light makes MGCB molecules dissociate into malachite green (MG) cations and OH^? ions, which induce the i‐motif DNA to unfold into the single‐stranded form due to the increase of the pH in the solution. Therefore, the pores are uncapped and the entrapped guest molecules are released. After the light is turned off, the MG cations recombine with the OH^? ions and return to the MGCB forms. The pH value thus decreases and the single‐stranded DNA switches back to i‐motif structure to cap the pore again. Because of the photon‐fueled MGCB‐dependent DNA conformation changes, the i‐motif DNA‐gated switch can be easily operated by turning the light on or off. Importantly, the opening/closing protocol is highly reversible and a partial cargo release can be easily achieved at will. This proof‐of‐concept may promote the application of DNA in the controlled release and can also provide a way to design various photon‐fueled controlled‐release systems using a combination of some photoirradiated pH‐jump systems and other kinds of pH‐sensitive linkers.     

Conjugated Polymers Combined with a Molecular Beacon for Label‐Free and Self‐Signal‐Amplifying DNA Microarrays

A conjugated polymer (CP) and molecular‐beacon‐based solid‐state DNA sensing system is developed to achieve sensitive, label‐free detection. A novel conjugated poly(oxadiazole) derivative exhibiting amine and thiol functional groups ( POX‐SH ) is developed for unique chemical and photochemical stability and convenient solid‐state on‐chip DNA synthesis. POX‐SH is soluble in most nonpolar organic solvents and exhibits intense blue fluorescence. POX‐SH is covalently immobilized onto a maleimido‐functionalized glass slide by means of its thiol group. Molecular beacons having a fluorescent dye or quencher molecule as the fluorescence resonance energy transfer (FRET) acceptor are synthesized on the immobilized POX‐SH layer through direct on‐chip oligonucleotide synthesis using the amine side chain of POX‐SH . Selective hybridization of the molecular beacon probes with the target DNA sequence opens up the molecular beacon probes and affects the FRET between POX‐SH and the dye or quencher, producing a sensitive and label‐free fluorescence sensory signal. Various molecular design parameters, such as the size of the stem and loop of the molecular beacon, the choice of dye, and the number of quencher molecules are systematically controlled, and their effects on the sensitivity and selectivity are investigated.     

Control and Implementation of a Real-Time Liquid Spotting System for Microarray Applications

This paper discusses the control and implementation of a real-time spotting system. It is intended for high-density high-yield microarray fabrication to facilitate diagnostic and research effort in genomics and proteomics. The method is based on a self-sensing fully automated aspiring/dispensing pin. System performance is evaluated by several batch runs with deionized water solutions of 0.3% fluorescent Cy-3 dye, which has similar physical properties to the deoxyribonucleic acid (DNA) probe materials. Experimental results show that this system is capable of fast and robust DNA/protein microarray fabrication in high volume while keeping spot size as small as 60 $muhbox{m}$ consistently. Based on the laser scanned images and experimental data of the spotted microarrays, it is also verified that this system can recognize and prevent the formation of abnormal spots.      

Soft Graphoepitaxy for Large Area Directed Self‐Assembly of Polystyrene‐block‐Poly(dimethylsiloxane) Block Copolymer on Nanopatterned POSS Substrates Fabricated by Nanoimprint Lithography

Polyhedral oligomeric silsequioxane (POSS) derivatives have been successfully employed as substrates for graphoepitaxial directed self‐assembly (DSA) of block copolymers (BCPs). Tailored POSS materials of tuned surface chemistry are subject to nanoimprint lithography (NIL) resulting in topographically patterned substrates with dimensions commensurate with the BCP block length. A cylinder forming polystyrene‐block‐polydimethylsiloxane (PS‐b‐PDMS) BCP is synthesized by sequential living anionic polymerization of styrene and hexamethylcyclotrisiloxane. The patterned POSS materials provide a surface chemistry and topography for DSA of this BCP and after solvent annealing the BCP shows well‐ordered microphase segregation. The orientation of the PDMS cylinders to the substrate plane could be controlled within the trench walls by the choice of the POSS materials. The BCP patterns are successfully used as on‐chip etch mask to transfer the pattern to underlying silicon substrate. This soft graphoepitaxy method shows highly promising results as a means to generate lithographic quality patterns by nonconventional methods and could be applied to both hard and soft substrates. The methodology might have application in several fields including device and interconnect fabrication, nanoimprint lithography stamp production, nanofluidic devices, lab‐on‐chip, or in other technologies requiring simple nanodimensional patterns.     

Fabrication, assembly, and characterization of molecular electronic components

One of the ultimate miniaturizations in nanotechnology is molecular electronics, where devices will consist of individual molecules. There are many complications associated with the use of molecules in electronic devices, such as the electronic perturbations in the molecule associated with being bonded to an electrode, how electrons traverse the metal-molecule junction, and the difficulty of macroscopically addressing single to very few molecules. Whether fabricating a test structure or a usable device, the use of self-assembly is fundamental to the fabrication of molecular electronic devices. We will discuss how to fabricate self-assembled monolayers into test assemblies and how to use intermolecular interactions to direct molecules into desired positions to create nanostructures and to connect functional molecules to the outside world. These assemblies serve as test structures for measurements on single or bundled molecules. The development of several experimental techniques, including various scanning probes, mercury drop junctions, break junctions, nanopores, crossed wires, and other techniques using nanoparticles have enabled the ability to test these structures and make reproducible measurements on single molecules. Many of these methods have been developed to test molecules with potential for integration into devices such as oligo (phenylene-ethynylene) molecules and other /spl pi/-conjugated molecules, in ensemble or single-molecule measurements.     

微流控聚合物链式反应芯片的多色荧光检测

为了实现微流控芯片上多目标DNA片段的同时检 测,建立了基于光棒匀光结构的微流控芯片多色 荧光检测系统。根据微流控芯片中的聚合物链式反应(PCR)反应腔的特点,设计了基于超亮 白光LED模组、光棒、二向色镜 和CCD的正交型荧光检测系统。CCD可一次采集微流控芯片上所有PCR反应腔中的荧光信号 ,通过滤光 片轮组合的变换,可实现多种荧光标记物的同时检测。采用荧光素钠溶液对激发光的均匀性 进行了测试, 激发产生的荧光图像均匀度达到93.99%,可满足微流控芯片上多反应 腔同时检测的需求。同时,以pUC-18人工质粒DNA作为标准品,开展了微流控荧光PCR生物实验,对系统性能进行验证。实验结 果表明:微 流控PCR反应腔的 DNA浓度变化与荧光信号的变化相一致,pUC-18样品的检测限达到0.05pg/uL,扩增 效率为97.28%,熔解曲线显示无引物二聚体产生,特异性好,达到了 商业化仪器的水平。     

基于8051F330的音频信号发生器的设计与实现

MMC/SD卡以其优越的性能,在单片机嵌入式设备中得到广泛应用.将MMC/SD卡作为外部掉电存储介质应用于音频信号发生器中,通过8051F330单片机上的SPI接口,实现单片机-MMC/SD卡的存储扩展,设计了此硬件平台上的MMC/SD卡的单片机驱动程序,并给出了相应的程序代码,满足音频信号发生器的大容量存储要求.     

Ionotronics Based on Horizontally Aligned Carbon Nanotubes

Controlled ion transport through ion channels of cell membranes regulates signal transduction processes in biological systems and has also inspired the thriving development of ionic electronics (ionotronics or iontronics) and biocomputing. However, for constructing highly integrated ionic electronic circuits, the integration of natural membrane‐spanning ion channel proteins or artificial nanomembrane‐based ionic diodes into planar chips is still challenging due to the vertically arranged architecture of conventional nanomembrane‐based artificial ionic diodes. Here, a new design of ionic diode is reported, which allows chip‐scale integration of ionotronics, based on horizontally aligned nanochannels made from multiwalled carbon nanotubes (MWCNTs). The rectification of ion transport through the MWCNT nanochannels is enabled by decoration of oppositely charged polyelectrolytes on the channel entrances. Advanced ionic electronic circuits including ionic logic gates, ionic current rectifiers, and ionic bipolar junction transistors (IBJT) are demonstrated on planar nanofluidic chips by stacking a series of ionic diodes fabricated from the same bundles of MWCNTs. The horizontal arrangement and facile chip‐scale fabrication of the MWCNT ionic diodes may enable new designs of complex but monolithic ionotronic systems. The MWCNT ionic diode may also prove to be an excellent platform for investigation of electrokinetic ion transport in 1D carbon materials.     

Fabrication and characterization of SPR chips with the modified bovine serum albumin

A facile surface plasmon resonance (SPR) chip is developed for small molecule determination and analysis. The SPR chip was prepared based on a self assembling principle, in which the modified bovine serum albumin (BSA) was directly self-assembled onto the bare gold surface. The surface morphology of the chip with the modified BSA was investigated by atomic force microscopy (AFM) and its optical properties were characterized. The surface binding capacity of the bare facile SPR chip with a uniform morphology is 8 times of that of the bare control SPR chip. Based on the experiments of immune reaction between cortisol antibody and cortisol derivative, the sensitivity of the facile SPR chip with the modified BSA is much higher than that of the control SPR chip with the un-modified BSA. The facile SPR chip has been successfully used to detect small molecules. The lowest detection limit is 5 ng/mL with a linear range of 5—100 ng/mL for cortisol analysis. The novel facile SPR chip can also be applied to detect other small molecules.     

Methods for passive fiber chip coupling of integrated opticaldevices

A useful technique for high precision passive coupling of single mode optical fibers to integrated optical devices is crucial for cost effective packaging especially in multiport devices like switches (N×N) and other WDM components. These devices were fabricated on two different material bases, silicon on insulator (SOI) and polymers. In both cases the waveguides are based on the oversized rib waveguide concept and utilize silicon as a substrate. Two possible fabrication processes for this passive fiber chip coupling IN or ON silicon are presented and compared. The first approach involves a technology similar to flip chip fabrication using a sub- and superstrate, that allows separate processing of v-grooves for fiber alignment and the integrated optical devices. The self aligned mounting of the chip is achieved by a v-shaped rib-groove combination created by wet chemical etching, where the rib is the exact negative of the groove so that the flip chip is put on precisely defined crystal planes rather than on sensitive edges, which would be the case when using rectangular alignment ribs. The second approach utilizes the same chip for waveguides and fiber alignment structures which makes it possible to define both in the same lithographic step and thereby eliminating any vertical displacement. Processing difficulties arise primarily from completely different processing requirements of fiber aligning v-grooves and integrated waveguides. The need to define patterns of the size of only several microns (μm) in the proximity to deep grooves makes the use of an electrophoretic photoresist necessary that is deposited via galvanic means on the extremely nonplanar surface. Both processes allow for fiber chip alignment precisions in the sub-μm range which was also experimentally verified with coupling losses as low as 0.7 dB per end-face. The fabrication processes along with experimental and theoretical results are presented     

Nanomaterial‐Based Fluorescent DNA Analysis: A Comparative Study of the Quenching Effects of Graphene Oxide,Carbon Nanotubes,and Gold Nanoparticles

A variety of nanomaterials have shown extraordinarily high quenching ability toward a broad range of fluorophores. Recently, there has been intense interest in developing new tools for fluorescent DNA analysis in solution or inside the cell based on this property, and by exploiting interactions between these nanoscale “superquenchers” and DNA molecules in the single‐stranded (ss‐) or double‐stranded (ds‐) forms. Here, a comparative study on the nanoqueching effects is performed by using a series of nanomaterials with different dimensions, i.e., gold nanoparticles (AuNPs, 0D), carbon nanotubes (CNTs, 1D), and graphene oxide (GO, 2D). The quenching efficiency, kinetics, differentiation ability, and influencing factors such as concentration and ionic strength are studied. Interestingly, GO exhibits superior quenching abilities to the other two materials in both the quenching efficiency and kinetics. As a result, a GO‐based fluorescent sensor, designed in a simple mix‐and‐detect format, can detect concentrations of DNA as low as 0.2 nM , which is better than either CNTs or AuNPs by an order of magnitude. This sensor can also differentiate single‐base mismatches much better than either CNTs‐ or AuNPs‐ based sensors. This study paves the way to better choice of nanomaterials for bioanalysis and elaborate design of biosensors for both in vitro diagnosis and in vivo bioimaging.     

A fluorescent porous silicon-based biosensor for small molecule detection

Fluorescent porous silicon was prepared as a stable biosensor chip substrate. The aminopropyltriethoxysilane (APTES) molecules are attached in the pores of the porous silicon with a crosslink method, and when the molecules are added into the chip, the fluorescence intensity is reduced according to the concentration of the APTES. Controlled experiments are also presented with the small molecule that cannot be covalently coupled, and the results show that this kind of sensor chip has better specificity. Compared with other conventional methods, this method is simple, quick and label-free.