Redox Capacitor to Establish Bio‐Device Redox‐Connectivity

Electronic devices process information and transduce energy with electrons, while biology performs such operations with ions and chemicals. To establish bio‐device connectivity, we fabricate a redox‐capacitor film from a polysaccharide (i.e., chitosan) and a redox‐active catechol. We report that these films are rapidly and repeatedly charged and discharged electrochemically via a redox‐cycling mechanism in which mediators shuttle electrons between the electrode and film (capacitance ≈ 40 F/g or 2.9 mF/cm²). Further, charging and discharging can be executed under bio‐relevant conditions. Enzymatic‐charging is achieved by electron‐transfer from glucose to the film via an NADPH‐mediated redox‐cycling mechanism. Discharging occurs by electron‐donation to O₂ to generate H₂O₂ that serves as substrate for peroxidase‐mediated biochemical reactions. Thus, these films offer the capability of inter‐converting electrochemical and biochemical inputs/outputs. Among potential applications, we anticipate that catechol–chitosan redox‐capacitor films could serve as circuit elements for molecular logic operations or for transducing bio‐based chemical energy into electricity.     

Empowering simulation analysis with data-management tools

When engineers engage in simulation studies, they first go through a modeling phase, i.e., the development of a computerized model, and then proceed to an analysis phase, i.e., the repeated execution of the computerized model for a variety of parameters. Since the advent of desktop computing, most simulation studies have relied on processing in interactive mode rather than in batch mode. This paper illustrates how batch processing of analysis activities allows the engineer to focus on drawing conclusions from the simulation experiments instead of wasting time in interactively setting up and conducting the analysis. It is concluded that since batch processing requires additional control capabilities, the analysis power of simulation can be fully realized only when simulation programs are integrated with data management tools     

Biomimetic Approach to Confer Redox Activity to Thin Chitosan Films

Electron transfer in biology occurs with individual or pairs of electrons, and is often mediated by catechol/o‐quinone redox couples. Here, a biomimetic polysaccharide‐catecholic film is fabricated in two steps. First, the stimuli‐responsive polysaccharide chitosan is electrodeposited as a permeable film. Next, the chitosan‐coated electrode is immersed in a solution containing catechol and the electrode is biased to anodically‐oxidize the catechol. The oxidation products covalently graft to the chitosan films as evidenced by electrochemical quartz crystal microbalance (EQCM) studies. Cyclic voltammetry (CV) measurements demonstrate that the catechol‐modified chitosan films are redox‐active although they are non‐conducting and cannot directly transfer electrons to the underlying electrode. The catechol‐modified chitosan films serve as a localized source or sink of electrons that can be transferred to soluble mediators (e.g., ferrocene dimethanol and Ru(NH₃) ₆Cl₃). This electron source/sink is finite, can be depleted, but can be repeatedly regenerated by brief (30 s) electrochemical treatments. Further, the catechol‐modified chitosan films can i) amplify currents associated with the soluble mediators, ii) partially‐rectify these currents in either oxidative or reductive directions (depending on the mediator), and iii) switch between regenerated‐ON and depleted‐OFF states. Physical models are proposed to explain these novel redox properties and possible precedents from nature are discussed.     

A rapid-response, high-sensitivity nanophase humidity sensor for respiratory monitoring

An ionic-type humidity sensor based on a plasma-deposited nanophase Si thin film was developed. Detection of relative humidity cycles between 20% and 90% was possible in /spl les/0.2 s with /spl sim/5 orders of magnitude variation in conductance. Such superior performance is attributable to the unique arrayed column-void network structure and ultrafine thickness (e.g., 50 nm) of the Si film as well as to the lateral electrode configuration. Our sensor can be miniaturized, integrated with signal processing circuits, and fabricated on plastics. A crucial implementation, where our sensor would be very suitable and beneficial, is respiratory monitoring.     

Mobeyes: smart mobs for urban monitoring with a vehicular sensor network

Vehicular sensor networks are emerging as a new network paradigm of primary relevance, especially for proactively gathering monitoring information in urban environments. Vehicles typically have no strict constraints on processing power and storage capabilities. They can sense events (e.g., imaging from streets), process sensed data (e.g., recognizing license plates), and route messages to other vehicles (e.g., diffusing relevant notification to drivers or police agents). In this novel and challenging mobile environment, sensors can generate a sheer amount of data, and traditional sensor network approaches for data reporting become unfeasible. This article proposes MobEyes, an efficient lightweight support for proactive urban monitoring based on the primary idea of exploiting vehicle mobility to opportunistically diffuse summaries about sensed data. The reported experimental/analytic results show that MobEyes can harvest summaries and build a low-cost distributed index with reasonable completeness, good scalability, and limited overhead     

基于智能手机平台的计算光学显微成像技术研究综述

计算光学显微成像技术将光学编码和计算解码相结合,通过光学操作和图像算法重建来恢复微观物体的多维信息,为显微成像技术突破传统成像能力提供了强大的助力。这项技术的发展得益于现代光学系统、图像传感器以及高性能数据处理设备的优化,同时也被先进的通信技术和设备的发展所赋能。智能手机平台作为高度集成化的电子设备,具有先进的图像传感器和高性能的处理器,可以采集光学系统的图像并运行图像处理算法,为计算光学显微成像技术的实现创造了全新的方式。进一步地,作为可移动通信终端,智能手机平台开放的操作系统和多样的无线网络接入方法,赋予了显微镜灵活智能化操控能力与丰富的显示和处理分析功能,可用于实现各种复杂环境下多样化的生物学检测应用。文中从四个方面综述了基于智能手机平台的计算光学显微成像技术,首先综述了智能手机平台作为光学成像器件的新型显微成像光路设计,接下来介绍了基于智能手机平台先进传感器的计算光学高通量显微成像技术,然后介绍了智能手机平台的数据处理能力和互联能力在计算显微成像中的应用,最后讨论了这项技术现存在的一些问题及解决方向。     

Exploiting edge capability for wireless sensor networking

As considerable progress is being made in wireless sensor networking, it is envisioned that sensor nodes will be on the cubic millimeter scale, posing stringent constraints on the processing, communication, and storage capabilities of sensor nodes. While it is important to continue pursuing novel algorithms and protocols to squeeze the most out of the existing design space (sensor nodes), it is equally important to explore a new design paradigm for future sensor networks to reduce the complexity burden on sensor nodes. We propose to exploit capabilities at the network edge (i.e., an edge-based approach). We overview existing approaches to this end and present a novel edge-based routing protocol, called BeamStar, as a case study. We show that exploiting edge capability provides a new dimension of freedom for wireless sensor networking, and is effective in relieving the processing, communication, and storage requirements of sensor nodes.     

Comparison of I-V, CV, and chemical datafor quality control studies of SiOxNy films on Si

Capacitance-voltage (CV) and current-voltage (I- V) measurements for SiO_xN_y films are compared with chemical data in order to provide some diagnostic capabilities in relating aberrant electrical characteristics with contaminants incorporated in the insulator film structure. In-process monitoring of film quality (utilizing electrical characteristics and chemical data) is especially critical in very large-scale integration (VLSI) processing control where the films are utilized both as an integral part of specific semiconductor device processing steps or as part of the semiconductor device structure     

Engineered Metal-Loaded Biohybrids to Promote the Attachment and Electron-Shuttling between Enzymes and Carbon Electrodes

The inorganic content and the catalytic performance pose metal-loaded enzyme nanoflowers as promising candidates for developing bioelectrodes capable of functioning without the external addition of a redox mediator. However, these protein-inorganic hybrids have yet to be successfully applied in combination with electrode materials. Herein, the synthesis procedure of these bionanomaterials is reproposed to precisely control the morphology, composition, and performance of this particular protein-mineral hybrid, formed by glucose oxidase and cobalt phosphate. This approach aims to enhance the adherence and electron mobility between the enzyme and a carbon electrode. The strategy relies on dressing the protein in a tailored thin nanogel with multivalent chemical motifs. The functional groups of the polymer facilitate the fast protein sequence-independent biomineralization. Furthermore, the engineered enzymes enable the fabrication of robust cobalt-loaded enzyme inorganic hybrids with exceptional protein loads, exceeding 90% immobilization yields. Notably, these engineered biohybrids can be readily deposited onto flat electrode surfaces without requiring chemical pre-treatment. The resulting bioelectrodes are robust and exhibit electrochemical responses even without the addition of a redox mediator, suggesting that cobalt complexes promote electron wiring between the active site of the enzyme and the electrode.     

Programmable “Semismart” Sensor: Relevance to Monitoring Antipsychotics

Mental health disorders are complex and poorly understood but would benefit from real‐time chemical analysis capable of assessing a patient's current status, personalizing a therapeutic action, and monitoring compliance. Here, an electrochemical sensor is reported for detecting the antipsychotic drug clozapine which is one of the most effective but under‐utilized drugs for managing schizophrenia. This sensor employs a composite film of multiwalled carbon nanotubes (CNTs) embedded within a matrix of the aminopolysaccharide chitosan. Chitosan allows programmable assembly of the composite film at an electrode address while the CNTs confer electrocatalytic activities that displace interfering serum peaks from the voltage region where clozapine oxidation occurs. Using differential pulse voltammetry, high sensitivities (limit of detection 0.05 × 10^–6m ) are demonstrated for clozapine analysis in buffer. In serum, clozapine sensitivity is reduced by an order of magnitude but still sufficient for clinical analysis. Finally, the detection of clozapine from the serum of a schizophrenia patient is demonstrated without the need for serum pretreatment. In the long term, it is envisioned that the CNT‐chitosan coated electrode could be integrated within a small array of other sensor types to enhance information‐extraction to allow mental health disorders to be better managed and better understood.     

Non-Monotonic Capacitance Change of Layered Ti3C2Tx MXene Film Structures under Increasing Compressive Stress

The progress in advanced electronic devices has imposed a great demand for developing flexible electrochemical power devices, which requires a comprehensive understanding of the mechanical–electrochemical coupling behavior of various energy storage materials. Unlike a monotonic capacitance increase of carbon-based double-layer supercapacitors, MXene-based flexible supercapacitors demonstrate a non-monotonic, i.e., “increase-then-decrease” capacitance behavior under the pressure range of 8488 kPa. This non-monotonic capacitance response to pressure is intrinsic to the MXene film as its charge storage is primarily determined by the surface activity, which can be readily affected by pressure-induced dissociation of functionalities, as well as the charge transporting kinetics as limited by the inherent layered structure. The findings described in this study not only expand the knowledge of mechanical–electrochemical coupling to layered MXenes under pressure, but also give a vital design guideline for flexible/stretchable MXene-based energy storage devices or other electronics.     

Hydrogel Patterning with Catechol Enables Networked Electron Flow

Reduction–oxidation (redox) reactions provide a distinct modality for biological communication that is fundamentally different from the more-familiar ion-based electrical modality. Biology uses these two modalities for communication through different systems (immune versus nervous), and uses different mechanisms to control the flow of the charge carriers: the flow of soluble ions is controlled using structural barriers (i.e., membranes) and gates (e.g., membrane-spanning protein channels), while the flow of insoluble electrons is controlled using redox-reaction networks. Here, a simple electrochemical approach to pattern catechols onto a flexible polysaccharide hydrogel is reported and it is demonstrated that the patterned catechol regions serve as nodes for the mediated flow of electrons through redox reactions. Electron flow through this node involves the switching of binary redox states (oxidized and reduced) and this node's redox state can be detected (i.e., “read”) by passively observing its optical absorbance, or actively switching its redox-state electrochemically. Further, this catechol node can be switched through biological mechanisms, and this enables the fabricated catechol node to be embedded within biochemical redox reaction networks to facilitate the spanning of bio-electronic communication. Thus, it is envisioned that catechols can emerge as a molecular equivalent to a transistor for miniaturize-able, deployable and sustainable redox-linked bioelectronics.     

Electrical Writing onto a Dynamically Responsive Polysaccharide Medium: Patterning Structure and Function into a Reconfigurable Medium

Historically, paper is the medium to write information. Here, the concept of writing is expanded from the addition of mass (i.e., ink) onto a static polysaccharide medium (i.e., paper), to the addition of electrical energy to a dynamically reconfigurable polysaccharide medium. Specifically, a dual‐responsive interpenetrating polysaccharide network is used as a dynamic medium. Electrical writing is achieved using an electrode pen to locally perform the cathodic electrolysis reactions that generate high‐pH regions that neutralize the interpenetrating chitosan chains and induce their self‐assembly into crystalline regions. Surprisingly, the gradients in structure induced by cathodic writing are stable even after the pH gradient has dissipated. Molecular modeling indicates that this stability results from structure‐induced changes in chitosan's pK_a. Various experimental approaches demonstrate that the changes in structure generated by cathodic writing alter the medium's mechanical, chemical, and biological properties. Importantly, the structure and information imparted into the film is reversible allowing the medium to be erased and new information to be written. Broadly, this work demonstrates the use of top‐down electrical inputs to induce bottom‐up structural changes in a biopolymer‐based medium and these structural changes fundamentally alter how this medium interacts chemically and biologically with its environment.     

Applications and design issues for mobile agents in wireless sensor networks

Recently, research interest has increased in the design, development, and deployment of mobile agent systems for high-level inference and surveillance in a wireless sensor network (WSN). Mobile agent systems employ migrating codes to facilitate flexible application re-tasking, local processing, and collaborative signal and information processing. This provides extra flexibility, as well as new capabilities to WSNs in contrast to the conventional WSN operations based on the client-server computing model. In this article we survey the potential applications of mobile agents in WSNs and discuss the key design issues for such applications. We decompose the agent design functionality into four components, that is, architecture, itinerary planning, middleware system design, and agent cooperation. This taxonomy covers low-level to high-level design issues and facilitates the creation of a component-based and efficient mobile agent system for a wide range of applications. With a different realization for each design component, it is expected that flexible trade-offs (e.g., between energy and delay) can be achieved according to specific application requirements.     

A multiresolution 100-GOPS 4-Gpixels/s programmable smart vision sensor for multisense imaging

This paper presents a multiresolution general-purpose high-speed machine vision sensor with on-chip image processing capabilities. The sensor comprises an innovative multiresolution sensing area, 1536 A/D converters, and a SIMD array of 1536 bit-serial processors with corresponding memory. The sensing area consists of an area part with 1536 /spl times/ 512 pixels, and a line-scan part with a set of rows with 3072 pixels each. The SIMD processor array can deliver more than 100 GOPS sustained and the on-chip pixel-analysing rate can be as high as 4Gpixels/s. The sensor is ideal for high-speed multisense imaging where, e.g., color, greyscale, internal material light scatter, and 3-D profiles are captured simultaneously. When running only 3-D laser triangulation, a data rate of more than 20 000 profiles/s can be achieved when delivering 1536 range values per profile with 8 bits of range resolution. Experimental results showing very good image characteristics and a good digital to analog noise isolation are presented.     

Tuning Interfacial Energy Barriers in Heterojunctions for Anti-Interference Sensing

Analytes with similar redox properties are normally difficult to distinguish through classic electrochemical methods. This becomes especially true for the on-site detection in seawater where the high salinity and complex chemical components can impose severe interference. Hereby introducing numerous nanoscale heterojunctions in the Cu/CuO/reduced graphene oxide (rGO)/polypyrrole (PPy) and Cu/CuO/rGO/chitosan electrochemical sensors, tunable interfacial energy barriers to exponentially regulate the electrochemical signal can be constructed. Importantly, these energy barriers are independent to redox but closely related to the electrostatic interaction from absorbed charged analytes such as Hg²⁺ and Cu²⁺. Moreover, the similar sensing principle is also valid for the energy barriers in p-n junctions as demonstrated in the Ni/NiO/ZnO/PPy sensor. The good anti-interference properties and ultrahigh sensitivity of this sensing mode offers new opportunities in trace analyte detection in harsh environments such as seawater.     

Integrated optical refractometer based on waveguide bend loss

This paper reports on a refractometer, which is based on measuring the throughput of a bent channel waveguide. A new type of channel waveguide, designed in SiON technology makes the throughput strongly dependent on the refractive index of a measurand fluid. This new waveguide can be designed for any measurand refractive index range between 1.00-5 in an aqueous solution with a refractive index of n=1.37. The sensor characteristics, make this simple sensor very interesting for controlling a chemical concentration during chemical processes, e.g., in the food and beverages industry     

Functional Polymer Brushes on Diamond as a Platform for Immobilization and Electrical Wiring of Biomolecules

For the biofunctionalization of electronic devices, polymer brushes can provide a route which allows combining the advantages of other commonly used approaches, such as immobilization of functional biomolecules via self assembled monolayers or coated polymer matrices: high stability and loading capacity, efficient electron transport, and excellent biocompatibility. In the work presented here, poly(methacrylic acid) brushes are prepared by self‐initiated photografting and photopolymerization on diamond electrodes. In this straightforward process no prior grafting of initiators is required since the initiation of the polymerization can be conveniently controlled by the hydrogen or oxygen termination of the diamond surface. Boron doped nanocrystalline diamond as an electrode material provides extreme chemical inertness and stability, inherent biocompatibility, and superior electrochemical properties, such as the large accessible potential window and low background currents. As a proof of concept we demonstrate the amperometric detection of glucose by polymer brushes covalently modified with the redox enzyme glucose oxidase and aminomethyl ferrocene as electron mediator. Characterization by X‐ray photoelectron spectroscopy and atomic force microscopy both indicate a high loading of the ferrocene mediator. Consistently, electrochemical cyclic voltammetry shows a multilayer equivalent loading of ferrocene and highly efficient electron transfer throughout the polymer film. Overall, functionalized polymer brushes can provide a promising platform for the immobilization and electrical wiring of biomolecules for bioelectronic and biosensing applications.     

Protein Rebinding to a Surface‐Confined Imprint

A novel strategy to prepare a selective ultrathin molecularly imprinted polymer (MIP) film directly on the gold‐based transducer surface for the peptide and protein detection in aqueous solution is demonstrated using a combination of epitope‐ and electrochemical surface imprinting approach. The synthetic peptide derived from the surface‐exposed C‐terminus of cytochrome c (Cyt c, residues 96–104) is selected as the template for the imprinting. It is labeled with a fluorescent dye in order to quantitatively evaluate all stages of the imprinting process in terms of changes in mean fluorescence intensity. The labeled peptide template is first chemisorbed on the gold surface as an oriented submonolayer through an additional C‐terminal cysteine. After electropolymerization, the template is stripped off electrochemically. To allow the imprinted sites to be confined to the surface, the film thickness is controlled to be comparable to the thickness of the peptide layer. This is achieved by the electropolymerization of scopoletin. Recognition capabilities of the films are characterized and the resulting MIP film is able to selectively capture the template peptide and the corresponding target protein. In case of the peptide recognition, the MIP film can discriminate even the single amino acid mismatched sequences of the target peptide.     

Paper‐Like,Thin, Foldable,and Self‐Healable Electronics Based on PVA/CNC Nanocomposite Film

The facile fabrication of thin and foldable self‐healing electronics on a poly(vinyl alcohol)/cellulose nanocrystal (PVA/CNC) composite film is reported. The self‐healing property of the PVA/CNC nanocomposite film can be activated by spraying water on the film surface, via dynamic formation of hydrogen bonding. The self‐healing efficiency of PVA/CNC is influenced by the content of CNC in the film, pH of the spraying solution, and the temperature. Via vacuum filtration and pattern transfer techniques, both a supercapacitor and a temperature sensor are fabricated on the same PVA/CNC film using gold nanosheet (AuNS) and polyaniline/multiwalled nanotube (PANI/MWCNT) electrodes. The fabricated supercapacitor with a gel‐type electrolyte exhibits a high electrochemical performance, and the thermoresistive temperature sensor shows a linear sensitivity with a fast response. Both devices exhibit superior mechanical stability and self‐healing property over 100 repetitive folding and five repetitive healing cycles, respectively, retaining the device performance owing to the percolated network of the conductive materials. This work demonstrates that our paper‐like thin PVA/CNC film‐based self‐healable devices can serve as highly durable and deformable electronics with longevity.