Solution‐Based Silicon in Thin‐Film Solar Cells

Solution‐based semiconductors give rise to the next generation of thin‐film electronics. Solution‐based silicon as a starting material is of particular interest because of its favorable properties, which are already vastly used in conventional electronics. Here, the application of a silicon precursor based on neopentasilane for the preparation of thin‐film solar cells is reported for the first time, and, for the first time, a performance similar to conventional fabrication methods is demonstrated. Because three different functional layers, n‐type contact layer, intrinsic absorber, and p‐type contact layer, have to be stacked on top of each other, such a device is a very demanding benchmark test of performance of solution‐based semiconductors. Complete amorphous silicon n‐i‐p solar cells with an efficiency of 3.5% are demonstrated, which significantly exceeds previously reported values.     

A modified magnetic resonance wireless power transfer system for capsule endoscopy

Background: The current study presents a fully planar wireless power transfer (WPT) scheme with the aim of providing enough power for capsule endoscopy performance. The method’s implementation on patients is more convenient than that of the previous conventional WPT plans in which a cylindrical wire coil is placed around the patient’s body. In addition to this, while using the present printed power receiver structure, the capsule’s internal space of opens up for other components such as the image sensors and data transmitting components. To improve the efficiency, a two-layer printed coil has been used as the transmitter, a two-layer printed coil as the receiver and a power coil on the transmitter side excited at 13.56 MHz.Results: Applying this method, the efficiency has increased to more than 2% for the proposed structure. Moreover, the effect of the body tissue on power efficiency has been simulated and measured and the maximum specific absorption rate (SAR) value considered for the desired system. Conclusions: The obtained results indicate that the proposed system meets the medical standards requirements.     

Amperometric, screen-printed, glucose biosensor for analysis of human plasma samples using a biocomposite water-based carbon ink incorporating glucose oxidase

This paper describes the optimisation of a screen-printing water-based carbon ink containing cobalt phthalocyanine (CoPC) and glucose oxidase (GOD) for the fabrication of a glucose biosensor. To optimise the performance of the biosensor, the loadings of the electrocatalyst (CoPC) and enzyme (GOD) were varied. It was found that the maximum linear range was achieved with a CoPC loading of 20% (m/m, relative to the mass of carbon) and a GOD loading of 628 U per gram of carbon. In our studies we chose to employ chronoamperometry, as this technique is commonly used for commercial devices. The optimum operating applied potential was found to be +0.5 V, following an incubation period of 60 s. The optimum supporting electrolyte was found to be 0.05 M phosphate buffer at pH 8.0, which resulted in a linear range of 0.2-5 mM, the former represents the detection limit. The sensitivity was 1.12 microA mM(-1). The effect of temperature was also investigated, and it was found that 40 degrees C gave optimal performance. The resulting amperometric biosensors were evaluated by measuring the glucose concentrations for 10 different human plasma samples containing endogenous glucose and also added glucose. The same samples were analysed by a standard spectrophotometric method, and the results obtained by the two different methods were compared. A good correlation coefficient (R(2) = 0.95) and slope (0.98) were calculated from the experimental data, indicating that the new devices hold promise for biomedical studies.     

Following the Morphology Formation In Situ in Printed Active Layers for Organic Solar Cells

The device performance of organic polymer:fullerene bulk heterojunction solar cells strongly depends on the interpenetrating network of the involved donor and acceptor materials in the active layer. Since morphology formation depends on the conditions of film preparation, the final morphology varies for different deposition methods. In order to understand and optimize industrial coating processes and, therefore, the performance of the solar cells produced, a deeper understanding of structure formation is important. In situ measurements of slot‐die printed polymer:fullerene active layers are presented that reveal insights into the evolution of the structure. Polymer crystallization and ordering is monitored by in situ grazing incidence wide angle X‐ray scattering (GIWAXS), and in situ grazing incidence small‐angle X‐ray scattering (GISAXS). The development of the morphology exhibits five stages independent of the drying conditions. Two growth rates are observed, an initial slow formation of poly(3‐hexylthiophene‐2,5‐diyl) crystallites in well‐aligned edge‐on orientation followed by a rapid crystal growth. By combining the GIWAXS and GISAXS measurements, a five‐stage growth and assembly process is found and described in detail along with a proposed model of the structural evolution. The findings are an important step in tailoring the assembly process.     

Poly(U)-Agarose Affinity Chromatography: Specific,Sensitivity Selectivity,and Affinity of Binding

These studie s were done to determine four basic intrinsic properties of poly(U)-agarose affinity columns. Specificity of binding studies demonstrated that binding to these columns is highly specific with >90% complementary binding and 3% noncomplementary binding. Sensitivity of binding studies indicated that a minimum sequence of 10 adenylates is required for detectable complementary binding. Selectivity of binding studies revealed that nonsequential adenylates in native RNAs and randomly distribut edadenylates in synthetic poly(A)-poly(C) co-polymers did not bind to poly(U)-agarose affinity columns. Whereas, affinity of binding studies demonstrated that A=U complementary base pairing is independent of chain-lengths of 25 a denylates and dependent of chain-lengths of <25 adenylates. Thus the data demonstrates that poly(U)-agarose affinity chromatography is scientifically sound and expedient for thedetection and isolation of poly(A)-containing cellular and viral RNAs.     

Scalable,Self‐Aligned Printing of Flexible Graphene Micro‐Supercapacitors

Graphene micro‐supercapacitors (MSCs) are an attractive energy storage technology for powering miniaturized portable electronics. Despite considerable advances in recent years, device fabrication typically requires conventional microfabrication techniques, limiting the translation to cost‐effective and high‐throughput production. To address this issue, we report here a self‐aligned printing process utilizing capillary action of liquid inks in microfluidic channels to realize scalable, high‐fidelity manufacturing of graphene MSCs. Microstructured ink receivers and capillary channels are imprinted on plastic substrates and filled by inkjet printing of functional materials into the receivers. The liquid inks move under capillary flow into the adjoining channels, allowing reliable patterning of electronic materials in complex structures with greatly relaxed printing tolerance. Leveraging this process with pristine graphene and ion gel inks, miniaturized all‐solid‐state graphene MSCs are demonstrated to concurrently achieve outstanding resolution (active footprint: <1 mm², minimum feature size: 20 µm) and yield (44/44 devices), while maintaining a high specific capacitance (268 µF cm^–2) and robust stability to extended cycling and bending, establishing an effective route to scale down device size while scaling up production throughput.     

Electrochemical Performance Enhancement of 3D Printed Electrodes Tailored for Enhanced Gas Evacuation during Alkaline Water Electrolysis

A zero-gap cell with porous electrodes is a promising configuration for alkaline water electrolysis. However, gas evacuation becomes a challenge in that case, as bubbles can get trapped within the electrode's 3D structure. This work considers a number of 3D printed electrode geometries with so-called triply periodic minimal surfaces (TPMS). The latter is a mathematically defined structure that repeats itself in three dimensions with zero mean curvature, and can therefore be expected to be particularly well-suited to enhance gas evacuation. Another advantage as compared to other state-of-the-art 3D electrodes like foams or felts lies in the fact that their porosity, which determines the available surface area, and their pore size or flow channel dimensions, which determines the degree of bubble entrapment, can be varied independently. By a combined experimental and modeling approach, this work then identifies the structural parameters that direct the performance of such 3D printed TPMS geometries toward enhanced gas evacuation. It is demonstrated that an optimal combination of these parameters allows, under a forced electrolyte flow, for a reduction in cell overpotential of more than 20%. This indicates that efforts in optimizing the electrode's geometry can give a similar electrochemical performance enhancement as optimizing its electro-catalytic composition.     

Photosystem II-based biosensors for the detection of pollutants

Photosystem II (PSII) is the supramolecular pigment–protein complex in the chloroplast, which catalyses the light-induced transfer of electrons from water to plastoquinone (PQ) in a process that evolves oxygen. The PSII complex is also known to bind some groups of (photosynthetic) herbicides, heavy metals and other chemical substances that affect its activity. The objective of this study is to provide an overview of the systems available for the bioassay of pollutants using biosensors that are based on the photochemical activity of PSII. Some applications of the PSII-based biosensors including herbicide, heavy metal monitoring and the detection of radiation in space experiments are reported.     

3D Printable Ceramic–Polymer Electrolytes for Flexible High‐Performance Li‐Ion Batteries with Enhanced Thermal Stability

This study establishes an approach to 3D print Li‐ion battery electrolytes with controlled porosity using a dry phase inversion method. This ink formulation utilizes poly(vinyldene fluoride) in a mixture of N‐methyl‐2‐pyrrolidone (good solvent) and glycerol (weak nonsolvent) to generate porosity during a simple drying step. When a nanosized Al₂O₃ filler is included in the ink, uniform sub‐micrometer pore formation is attained. In other words, no additional processing steps such as coagulation baths, stretching, or etching are required for full functionality of the electrolyte, which makes it a viable candidate to enable completely additively manufactured Li‐ion batteries. Compared to commercial polyolefin separators, these electrolytes demonstrate comparable high rate electrochemical performance (e.g., 5 C), but possess better wetting characteristics and enhanced thermal stability. Additionally, this dry phase inversion method can be extended to printable composite electrodes, yielding enhanced flexibility and electrochemical performance over electrodes prepared with only good solvent. Finally, sequentially printing this electrolyte ink over a composite electrode via a direct write extrusion technique has been demonstrated while maintaining expected functionality in both layers. These ink formulations are an enabling step toward completely printed batteries and can allow direct integration of a flexible power source in restricted device areas or on nonplanar surfaces.     

In Situ Probing the Crystallization Kinetics in Gas-Quenching-Assisted Coating of Perovskite Films

The pursuit of commercializing perovskite photovoltaics is driving the development of various scalable perovskite crystallization techniques. Among them, gas quenching is a promising crystallization approach for high-throughput deposition of perovskite films. However, the perovskite films prepared by gas-quenching assisted blade coating are susceptible to the formation of pinholes and frequently show inferior crystallinity if the interplay between film coating, film drying, and crystallization kinetics is not fully optimized. That arguably requires a thorough understanding of how single processing steps influence the crystallization kinetics of printed perovskite films. Here, in situ optical spectroscopies are integrated into a doctor-blading setup that allows to real-time monitor film formation during the gas-quenching process. It is found that the essential role of gas quenching treatment is in achieving a smooth and compact perovskite film by controlling the nucleation rate. Moreover, with the assistance of phase-field simulations, the role of excessive methylammonium iodide is revealed to increase grain size by accelerating the crystal growth rate. These results show a tailored control of crystal growth rate is critical to achieving optimal film quality, leading to fully printed solar cells with a champion power conversion efficiency of 19.50% and mini solar modules with 15.28% efficiency are achieved.     

Scaling Printable Zn–Ag2O Batteries for Integrated Electronics

Printed batteries are an emerging solution for integrated energy storage using low‐cost, high accuracy fabrication techniques. While several printed batteries have been previously shown, few have designed a battery that can be incorporated into an integrated device. Specifically, a fully printed battery with a small active electrode area (<1 cm²) achieving high areal capacities (>10 mAh cm^?2) at high current densities (1–10 mA cm^?2) has not been demonstrated, which represents the minimum form‐factor and performance requirements for many low‐power device applications. This work addresses these challenges by investigating the scaling limits of a fully printed Zn–Ag₂O battery and determining the electrochemical limitations for a mm²‐scale battery. Processed entirely in air, Zn–Ag₂O batteries are well suited for integration in typical semiconductor packaging flows compared to lithium‐based chemistries. Printed cells with electrodes as small as 1 mm² maintain steady operating voltages above (>1.4 V) at high current densities (1–12 mA cm^?2) and achieve the highest reported areal capacity for a fully printed battery at 11 mAh cm^?2. The findings represent the first demonstration of a small, packaged, fully printed Zn–Ag₂O battery with high areal capacities at high current densities, a crucial step toward realizing chip‐scale energy storage for integrated electronic systems.     

Emerging Technologies for the Electrochemical Detection of Bacteria

Infections are a huge economic liability to the health care system, although real‐time detection can allow early treatment protocols to avoid some of this cost and patient morbidity and mortality. Pseudomonas aeruginosa (PA) is a drug‐resistant gram‐negative bacterium found ubiquitously in clinical settings, accounting for up to 27% of hospital acquired infections. PA secretes a vast array of molecules, ranging from secondary metabolites to quorum sensing molecules, of which many can be exploited to monitor bacterial presence. In addition to electrochemical immunoassays to sense bacteria via antigen–antibody interactions, PA pertains a distinct redox‐active virulence factor called pyocyanin (PYO), allowing a direct electrochemical detection of the bacteria. There has been a surge of publications relating to the electrochemical tracing of PA via a myriad of novel biosensing techniques, materials, and methodologies. In addition to indirect methods, research approaches where PYO has been sensitively detected using surface modified electrodes are reviewed and compared with conventional PA‐sensing methodologies. This review aims at presenting indirect and direct electrochemical methods currently developed using various surface modified electrodes, materials, and electrochemical configurations on their electrocatalytic effects on sensing of PA and in particular PYO.     

Instructions for Authors

<正>Aims and scope SCIENCE CHINA Life Sciences(Sci China Life Sci)is a journal published monthly in English by the Chinese Academy of Sciences,and co-sponsored by the National Natural Science Foundation of China.It is published in both printed and electronic forms by Science China Press and Springer.The journal publishes high-quality papers from a wide range of areas in life sciences,including biology,medicine,and agriculture and ecology.Six categories of papers are published:Review,Research Paper,CUSBEA Article Series,Insight,Letter to the Editor,and News and Views.     

Instructions for Authors

<正>Aims and scope SCIENCE CHINA Life Sciences(Sci China Life Sci)is a journal supervised by the Chinese Academy of Sciences,and co-sponsored by the Chinese Academy of Sciences and National Natural Science Foundation of China.It is published in both printed and electronic forms by Science China Press and Springer.     

Instructions for Authors

<正>Aims and scope SCIENCE CHINA Life Sciences(Sci China Life Sci)is a journal published monthly in English by the Chinese Academy of Sciences,and co-sponsored by the National Natural Science Foundation of China.It is published in both printed and electronic forms by Science China Press and Springer.     

Electrochemical assay for the determination of nitric oxide metabolites using copper(II) chlorophyllin modified screen printed electrodes

This work presents a novel electrochemical assay for the collective measurement of nitric oxide (NO) and its metabolites nitrite (NO₂⁻) and nitrate (NO₃⁻) in volume miniaturized sample at low cost using copper(II) chlorophyllin (CuCP) modified sensor electrode. Zinc oxide (ZnO) incorporated screen printed carbon electrode (SPCE) was used as a host matrix for the immobilization of CuCP. The morphological changes of the ZnO and CuCP modified electrodes were investigated using scanning electron microscopy. The electrochemical characterization of CuCP–ZnO–SPCE exhibited the characteristic quasi-reversible redox peaks at the potential +0.06 V versus Ag/AgCl. This biosensor electrode showed a wide linear range of response over NO concentrations from 200 nM to 500 μM with a detection limit of 100 nM and sensitivity of 85.4 nA μM⁻¹. Furthermore, NO₂⁻ measurement showed linearity of 100 nM to 1 mM with a detection limit of 100 nM for NO₂⁻ and sensitivity of 96.4 nA μM⁻¹. Then, the concentration of NO₃⁻ was measured after its enzymatic conversion into NO₂⁻. Using this assay, the concentrations of NO, NO₂⁻, and NO₃⁻ present in human plasma samples before and after beetroot supplement were estimated using suitable membrane coated CuCP–ZnO–SPCE and validated with the standard Griess method.     

Organic charge transfer complex based printable biosensor

This paper describes the preparation of an organic charge transfer complex (CTC) based printable enzyme electrode. CTC crystals were prepared by mixing TCNQ powder with TTF solution (in acetonitrile). Glucose oxidase (GOD) was adsorbed at the CTC crystal surface in a monolayer. A printable paste was prepared by mixing GOD-adsorbed crystals with a binder and a solvent. This paste was applied to an electrode cavity and vacuum dried. A thin layer of gelatin was cast on the paste filled dried electrode, and cross-linked with glutaraldehyde in the dry condition. The sensors were fixed in a flow injection system, and continuously polarized at 0·15 V and 37°C, and the samples were automatically injected every 30 min. The developed sensors produced a huge response curren with an extended linear range of detection (0–100 mM) and the response was unaffected by the presence of normal oxygen in the buffer solution. The sensor showed excellent stability. The performance of the sensors was significantly influenced by the binder used.