Scalable Manufacturing Technology Research Articles

Scalable Fabrication of Flexible Supercapacitor Electrodes Using Sustainable Water‐Based Onion‐like Carbon Inks

AbstractThe increasing usage of electrical energy storage solutions demands for cost effective, scalable and sustainable manufacturing technologies. Deposition of functional inks, carrying electrochemically active materials is a suitable technique as it delivers material with selected properties only to required locations. However, the production of stable dispersions featuring high concentrations of active material ‐ necessary for effective deposition ‐ is challenging. Here we present an approach to print supercapacitor electrodes with onion‐like carbon as active material, using a simple, cost‐effective process as well as a water‐based ink. The ink is highly stable and can be deposited by spray and inkjet techniques. The fabricated electrodes offer a capacitance of up to 14 mF cm−2 (27 F g−1) and retained 97 % of their initial capacitance after 5000 cycles, demonstrating excellent performance and stability of the coating.

Biomimetic Structural Design of Fabric for Low‐Cost, Scalable, and Highly Efficient Off‐Grid Solar‐Driven Water Purification

AbstractInterfacial solar‐vapor generation (ISVG) is an emerging technology for water purification. However, high cost, low evaporation rate, clogging issues, and limited solar utilization under natural condictions greatly hinder its practical application. Herein, inspired by the aligned microstructure of dragonfly wings, a 3D microarray structure composed of vertically aligned hierarchical and hydrophilic carbon fibers (CFs) is constructed using a scalable fiber manufacturing technology. The microarray structure of the high‐thermal‐conductivity CFs with nanocapillaries contributes to the fast mass (steam and salt ions) and heat transfer as well as high omnidirectional light absorption. More importantly, due to the strong multiscale capillary effect, the formed 3D water evaporation surface containing abundant micro‐meniscuses and nanoscale thin water layers in the CFs arrays effectively reduces the evaporation enthalpy and creates more water/air interfaces, leading to the significant increasing evaporation rate. As a result, a high evaporation rate of 2.21 kg m−2 h−1 under one‐sun irradiation can be achieved. Moreover, the off‐grid water treatment device assembled with multiple 3D CFs‐based customized spherical evaporators can obtain a high pure water collection of 10.71 kg m−2 per day without salt accumulation under real environmental conditions. This work demonstrates a high‐efficiency, cost‐effective, and scalable strategy for high‐performance ISVG.

Roll-to-roll solvent-free manufactured electrodes for fast-charging batteries

Roll-to-roll solvent-free manufactured electrodes for fast-charging batteries

Organ-on-a-Chip Platform with an Integrated Screen-Printed Electrode Array for Real-Time Monitoring Trans-Epithelial Barrier and Bubble Formation.

Cellular tight junctions play a key role in establishing a barrier between different compartments of the body by regulating the selective passage of different solutes across epithelial and endothelial tissues. Over the past decade, significant efforts have been conducted to develop more clinically relevant "organ-on-a-chip" models with integrated trans-epithelial electrical resistance (TEER) monitoring systems to help better understand the fundamental underpinnings of epithelial tissue physiology upon exposure to different substances. However, most of these platforms require the use of high-cost and time-consuming photolithography processes, which limits their scalability and practical implementation in clinical research. To address this need, we have developed a low-cost microfluidic platform with an integrated electrode array that allows continuous real-time monitoring of TEER and the risk of bubble formation in the microfluidic system by using scalable manufacturing technologies such as screen printing and laser processing. The integrated printed electrode array exhibited excellent stability (with less than ∼0.02 Ω change in resistance) even after long-term exposure to a complex culture medium. As a proof of concept, the fully integrated platform was tested with HMT3522 S1 epithelial cells to evaluate the tight barrier junction formation through TEER measurement and validated with standard immunostaining procedures for Zonula occludens-1 protein. This platform could be regarded as a stepping stone for the fabrication of disposable and low-cost organ and tissue-on-a-chip models with integrated sensors to facilitate studying the dynamic response of epithelial tissues to different substances in more physiologically relevant conditions.

Electronic-free and low-cost wireless sensor tag for monitoring fish freshness

Real-time monitoring of fish products throughout the supply chain is critically important for proper tracking of fish quality and spoilage to eliminate food waste. However, most of the existing food freshness monitoring technologies are based on complex and costly sensors that lack specificity to direct biomarkers of product quality rendering them impractical for scalable low-cost production and integration into standard food packaging products. To address these issues, we present an electronic-free wireless sensor tag that can selectively monitor hypoxanthine (HX) as a specific biomarker to indicate the spoilage of fish products. The sensor tag is composed of a working and reference coil in a self-calibrating, dual-resonator configuration. The working coil is covered with a stimuli-responsive bilayer polymer structure that degrades only when high levels of HX are produced in spoiled fish products, resulting in a discernible change in the resonant characteristics of the coil. Detecting this change with respect to the reference antenna using a contactless external reader provides a differential mode of sensing to avoid environmental noise and enhance accuracy. The sensor fabrication process takes advantage of scalable and cost-effective manufacturing technologies including laser processing of metalized films and solution casting approaches. Systematic design of resonant coils and optimization of functional HX responsive coatings were performed to identify structures that provided the required spoilage detection threshold of (>2.25 mM HX) which is an indicator of fish spoilage in package products. As a proof of concept, the sensor tag’s performance was validated in a commercially packaged fish product, highlighting its ability to effectively differentiate spoiled products from fresh products in refrigerated conditions. The high selectivity exhibited by this technology puts forth a new platform that merges stimuli-responsive sensing with electronic-free wireless telemetry to develop biomarker-specific sensors for a wide range of intelligent food packaging applications.

Pulsed Electrophoretic Deposition of Nanocarbons and Their Optical, Thermal, and Electrical Applications

Electrophoretic deposition (EPD) is a well-established, scalable industrial manufacturing technology for depositing a wide variety of coatings across a broad range of substrates, geometries and sizes. Conventional electrophoretic deposition (EPD) is the migration of small, suspended particles in a liquid driven by a constant electrical potential difference. As a subset of electrodeposition, EPD has been used to deposit layers on various conducting and semiconducting surfaces from polar, aqueous, and non-polar suspensions. On the other hand, state of the art developments within nanoscience and nanotechnology has opened a new vista for the field of nanocarbon materials. Nanostructured carbon materials, such as carbon nanotubes, graphene, carbon quantum dots, etc., exhibit excellent physical and chemical properties, and have been gaining attention in both fundamental research and technological applications.In this invited presentation, Faraday Technology will discuss an innovative electrophoretic deposition (EPD) manufacturing process, based on the use of pulsed electric fields, for controlled, reproducible, scalable deposition of a wide variety of nanocarbon based coatings across a broad range of substrates, geometries and sizes (Figure 1). The effects of waveforms, electrolytes, substrates, etc. on the formation of robust and uniform coating will be discussed in this talk. The optical and electrical properties, and environmental survivability of nanocarbon coatings will be demonstrated via a variety of testing or characterizations. Faraday will also introduce their applications ranging from low-reflective coatings, solar absorber, high emissivity coatings, to thin film electrodes for energy storage.In summary, a scalable EPD manufacturing process for fabricating nanocarbon based coatings have been developed at Faraday for various applications ranging from optical, thermal, to electrical fields. Acknowledgements: The financial support from NASA SBIR program through contracts No. 80NNSC18P2062 & 80NSSC19C0177, DOD DMEA STTR program through grant No. HQ0727-21-P-0029, DARPA SBIR program through grant No. W31P4Q-22-C-0014, DOD MDA STTR program through grant No. HQ0147-19-C-7065, DOD Air Force SBIR program through grant No. FA9453-19-P-0573, NASA SBIR program through contracts No. 80NSSC20C0287 are acknowledged. Figure 1

Halloysite nanotubes strengthened electrospinning composite nanofiber membrane for on-skin flexible pressure sensor with high sensitivity, good breathability, and round-the-clock antibacterial activity

Flexible pressure sensors that can in real-time detect and monitor external stimuli and physiological signals accurately and continuously are highly desirable. However, it is still challenging to prepare stretchable, breathable, and antibacterial substrates that can be served in on-skin flexible pressure sensors. Herein, a stretchable and breathable on-skin flexible pressure sensor with high sensitivity and round-the-clock antibacterial activity is fabricated by integrating silver phosphate nanoparticles modified halloysite nanotubes (Hal@Ag3PO4) into thermoplastic polyurethane (TPU) matrix via electrospinning. The sensor is constructed by using the Hal@Ag3PO4 decorated TPU electrospinning nanofiber membrane as flexible substrates and using silver nanowires/TPU nanofiber composites as dielectric layer. The introduction of Hal@Ag3PO4 nanofillers significantly improves the sensitivity and the mechanical properties of the sensor. In terms of pressure sensing, the device exhibits high sensitivity (6.7 kPa−1), fast response time (60 ms), low detection limit (4.8 Pa), good air permeability (130 mm/s) and well stability of 3000 cycles without fatigue. Importantly, it shows the round-the-clock antibacterial activity for Escherichia coli and Staphylococcus aureus, benefitting for the continuous detection and monitoring by wearing onto human skin. Except that, we build a sensor array that can clearly recognize the pressure location. Thus, this strategy that combines electrospinning TPU nanofiber membranes with Hal@Ag3PO4 antibacterial nanofillers demonstrates a low-cost and scalable manufacturing technology for on-skin flexible pressure sensors with promising applications in electronic skin and smart wound dressing.

Damage location sensing in carbon fiber composites using extrusion printed electronics

Structural Health Monitoring (SHM) uses sensors in advanced engineering structures to evaluate integrity and detect damage or deformation affecting structural performance, e.g. cracks, holes, or corrosion. Carbon fiber (CF) textile composites are commonly used to reinforce structures such as aircraft, vehicles, or bridges due to their high tensile strength to weight ratio, chemical resistance, and thermal and electrical conductivity. Printing electronics on textiles is a scalable manufacturing technology combining the physical properties of textile materials with the added functionality of electronic elements making them self-sensing. Extrusion printing is a contactless digital printing method to print electrical conductors and passive circuit elements. This paper proposes to combine conventional CF composite manufacturing processes with printed conductors to create self-sensing CF textile composites. Damage is sensed by measuring resistance changes in a CF sheet. Contacts are extrusion printed directly on woven CF sheets using silver flake ink. A multiplexed Kelvin Double Bridge circuit is the read-out interface. This allows small resistance changes due to damage to be measured in a four-point configuration. The circuit is connected to the printed contacts on the CF sheet through multiplexers to detect damage in different locations. This 2D digital sensor can detect the location and size of damage holes for SHM. The resolution of the sensor is controlled by the location and spacing of the silver electrodes, which were studied experimentally and by simulation. The resolution is 26 mm in the current direction and 16 mm in the orthogonal direction. The threshold of detectable damage is 4 mm2. Simulation of the sensor as an isotropic 2D conductor shows good agreement with experimental results for the orthotropic fabric. The resultant sensing device could be integrated into many composite structures as one of its layers or simply printed on the surface to create smart structures.

Research progress on the cathode and anode of aqueous zinc ion battry

Electrochemical energy storage problems become a worldwide research direction. Now Lithium-ion batteries (LIBs) are the most common battery product. However, LIBs still has many shortcomings such as, safety problems, a scarcity of lithium, and high price. Rechargeable aqueous-based zinc ion batteries (AZIBs) with lower costs, fewer safety risks as well as abundant zinc reserves have attracted extensive research interest. For the current electrode materials of AZIBs, for example, Mn-based materials, V-based materials and metallic zinc, scientists have done in-depth research to develop the performance of the materials, but complex processes are still inevitable. As a result, sustainable and scalable manufacturing technology and electrode materials with high capacity and the longer service life is the research direction.

Scalability comparison between 50 and 500 liter stirred tank bioreactor for production of rAAV viral vector

Viral vectors are a new class of biologics which facilitate gene transfer and modification in living cells, potentially treating a multitude of conditions with genetic causes. Scalable manufacturing technologies are critical to ensuring these cutting-edge medicines can be produced in sufficient quantities to meet the needs of process development, clinical trials, and ultimately commercial manufacturing Mol. Ther. 2016; 3: 15049." data-url="http://dx.doi.org/10.1038/mtm.2015.49">[1]Ayuso E. Manufacturing of recombinant adeno-associated viral vectors: new technologies are welcome. Mol. Ther. 2016; 3: 15049.Ayuso E. Manufacturing of recombinant adeno-associated viral vectors: new technologies are welcome. Mol. Ther. 2016; 3: 15049.Ayuso E. Manufacturing of recombinant adeno-associated viral vectors: new technologies are welcome. Mol. Ther. 2016; 3: 15049.. As viral vector-based products have only relatively recently received regulatory approval, public information on scalable optimization of these processes is very limited. Abeona Therapeutics is a gene therapy company developing novel gene replacement therapies for rare inherited diseases. These conditions can impact development and limit both quality of life and/or life expectancy et al. Estimation of impact of RPE65-mediated inherited retinal disease on quality of life and the potential benefits of gene therapy. Br. J. Ophthalmol. 2019; 103(11): 1610–14. " data-url="http://dx.doi.org/10.1136/bjophthalmol-2018-313089">[2]Lloyd A, Piglowska N, Ciulla T et al. Estimation of impact of RPE65-mediated inherited retinal disease on quality of life and the potential benefits of gene therapy. Br. J. Ophthalmol. 2019; 103(11): 1610–14. . These transformative medicines can be used to replace a defective gene with a functional copy, silence a defective gene or even directly edit genes Nat. Rev. Drug Discov. 2019; 18(5): 358–78. " data-url="http://dx.doi.org/10.1038/s41573-019-0012-9">[3]Wang D, Tai PWL, Gao G. Adeno-associated virus vector as a platform for gene therapy delivery. Nat. Rev. Drug Discov. 2019; 18(5): 358–78. , J. Virol. 1999; 73(5): 3994–4003. " data-url="http://dx.doi.org/10.1128/jvi.73.5.3994-4003.1999">[4]Xiao W, Chirmule N, Berta SC, McCullough B, Gao G, Wilson JM. Gene therapy vectors based on adeno-associated virus type 1. J. Virol. 1999; 73(5): 3994–4003. . We evaluated the Pall Allegro™ STR bioreactor family as an rAAV vector production platform and evaluated the scalability of the PEI-mediated transfection manufacturing process for rAAV at the 50 L and 500 L working volume. Process scalability was evaluated based on cell growth, metabolic profile, and vector production. This testing demonstrates that control of key process parameters enables a scalable vector production process between the 50 L and 500 L scale using Allegro STR single use bioreactors.

Developing Activated Carbon Veil Electrode for Sensing Salivary Uric Acid.

The paper describes the development of a carbon veil-based electrode (CVE) for determining uric acid (UA) in saliva. The electrode was manufactured by lamination technology, electrochemically activated and used as a highly sensitive voltammetric sensor (CVEact). Potentiostatic polarization of the electrode at 2.0 V in H2SO4 solution resulted in a higher number of oxygen and nitrogen-containing groups on the electrode surface; lower charge transfer resistance; a 1.5 times increase in the effective surface area and a decrease in the UA oxidation potential by over 0.4 V, compared with the non-activated CVE, which was confirmed by energy dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, chronoamperometry and linear sweep voltammetry. The developed sensor is characterized by a low detection limit of 0.05 µM and a wide linear range (0.09–700 µM). The results suggest that the sensor has perspective applications for quick determination of UA in artificial and human saliva. RSD does not exceed 3.9%, and recovery is 96–105%. UA makes a significant contribution to the antioxidant activity (AOA) of saliva (≈60%). In addition to its high analytical characteristics, the important advantages of the proposed CVEact are the simple, scalable, and cost-effective manufacturing technology and the absence of additional complex and time-consuming modification operations.

Monolithic wood biochar as functional material for sustainability

AbstractTrees are crucial to humankind's survival, releasing the oxygen we breathe, growing the fruits we eat, and supplying wood to build and warm our shelters. Heating wood at 300°C‐800°C with little or no oxygen creates wood biochar, a carbonaceous product. Wood biochar monoliths have a continuous carbon matrix and morphological features that resemble anatomical elements in a tree, including xylem and phloem, which transport water from the root and deliver sugars from leaves to individual cells. Structurally and chemically, monolithic wood biochar belongs to nanoporous carbons (NPCs) consisting of carbon nanotubes arrays and integrated graphene sheets. Researchers have extensively explored NPCs as functional materials for applications essential to sustainability, including electrical energy storage, water purification, and CO2 capture. However, the lack of scalable manufacturing technology continues to hinder the large‐scale utilization of NPCs despite their demonstrated superiority in enhancing materials performance. Derived from abundant woody biomass with simple processes, wood biochar monoliths offer a new opportunity for overcoming this limitation. This review documents recent progress in applying wood biochar monoliths in areas critical to sustainability, focusing on electrical energy storage and water purification. This progress has revealed the potential of monolith wood biochar as a greener, more cost‐effective, and scalable NPC in enhancing sustainability and opened the door to a new field that is both exciting and relevant. The review concludes with a perspective on the future research direction.

Printed and hybrid integrated electronics using bio-based andrecycled materials\u2014increasing sustainability with greener materials andtechnologies

Printed and hybrid integrated electronics produced from recycled andrenewable materials can reduce the depletion of limited material resources whileobtaining energy savings in small electronic applications and their energy storage.In this work, bio-based poly(lactic acid) (PLA) and recycled polyethyleneterephthalate (rPET) were fabricated in film extrusion process and utilized as asubstrate in ultra-thin organic photovoltaics (OPV). In the device structure, metalsand metal oxides were replaced by printing PEDOT:PSS, carbon and aminoacid/heterocycles. Scalable, energy-efficient fabrication of solar cells resulted inefficiencies up to 6.9% under indoor light. Furthermore, virgin-PET was replacedwith PLA and rPET in printed and hybrid integrated electronics where surface-mountdevices (SMD) were die-bonded onto silver-printed PLA and virgin-PET films toprepare LED foils followed by an overmoulding process using the rPET and PLA. As aresult, higher relative adhesion of PLA-PLA interface was obtained in comparisonwith rPET-PET interface. The obtained results are encouraging from the point ofutilization of scalable manufacturing technologies and natural/recycled materials inprinted and hybrid integrated electronics. Assessment showed a considerable decreasein carbon footprint, about 10–85%, mainly achieved through replacing of silver,virgin-PET and modifying solar cell structure. In outdoor light, the materials withlow carbon footprint can decrease energy payback times (EPBT) from ca. 250 days tounder 10 days. In indoor energy harvesting, it is possible to achieve EPBT of lessthan 1 year. The structures produced and studied herein have a high potential ofproviding sustainable energy solutions for example in IoT-relatedtechnologies.

Integrated sensing and delivery of oxygen for next-generation smart wound dressings

Chronic wounds affect over 6.5 million Americans and are notoriously difficult to treat. Suboptimal oxygenation of the wound bed is one of the most critical and treatable wound management factors, but existing oxygenation systems do not enable concurrent measurement and delivery of oxygen in a convenient wearable platform. Thus, we developed a low-cost alternative for continuous O2 delivery and sensing comprising of an inexpensive, paper-based, biocompatible, flexible platform for locally generating and measuring oxygen in a wound region. The platform takes advantage of recent developments in the fabrication of flexible microsystems including the incorporation of paper as a substrate and the use of a scalable manufacturing technology, inkjet printing. Here, we demonstrate the functionality of the oxygenation patch, capable of increasing oxygen concentration in a gel substrate by 13% (5 ppm) in 1 h. The platform is able to sense oxygen in a range of 5–26 ppm. In vivo studies demonstrate the biocompatibility of the patch and its ability to double or triple the oxygen level in the wound bed to clinically relevant levels.

Evolving Strategies for Producing Multiscale Graphene-Enhanced Fiber-Reinforced Polymer Composites for Smart Structural Applications.

Graphene has become an important research focus in many current fields of science including composite manufacturing. Developmental work in the field of graphene‐enhanced composites has revealed several functional and structural characteristics that promise great benefits for their use in a broad range of applications. There has been much interest in the production of multiscale high‐performance, lightweight, yet robust, multifunctional graphene‐enhanced fiber‐reinforced polymer (gFRP) composites. Although there are many reports that document performance enhancement in materials through the inclusion of graphene nanomaterials into a matrix, or its integration onto the reinforcing fiber component, only a few graphene‐based products have actually made the transition to the marketplace. The primary focus of this work concerns the structural gFRPs and discussion on the corresponding manufacturing methodologies for the effective incorporation of graphene into these systems. Another important aspect of this work is to present recent results and highlight the excellent functional and structural properties of the resulting gFRP materials with a view to their future applications. Development of clear standards for the assessment of graphene material properties, improvement of existing materials and scalable manufacturing technologies, and specific regulations concerning human health and environmental safety are key factors to accelerate the successful commercialization of gFRPs.

Development of the TIP-HOLE gas avalanche structure for nuclear physics/astrophysics applications with radioactive isotope beams: preliminary results.

We discuss the operational principle and performance of new micro-pattern gaseous detectors based on the multi-layer Thick Gaseous Electron Multiplier (M-THGEM) concept coupled to a needle-like anode. The new gas avalanche structure aims at high-gain operation in nuclear physics and nuclear astrophysics applications with radioactive isotope beams. It is thereafter named TIP-HOLE gas amplifier, and consists of a THGEM or a two-layers M-THGEM mounted in a WELL configuration. The avalanche electrodes are collected by thin conductive needles (with up to a few ten μm radius and a height of 100 μm), located at the center of the hole and acting as a point-like anode. The bottom area of the needle could be surrounded by a cylindrical cathode strip in order to increase the electron collection efficiency. The electric field lines from the drift region above the M-THGEM are focused into the holes, and then forced to converge on the needle tip. An extremely high field is reached at the top of the needle, creating a point-like avalanche process. Stable, high-gain operations in a wide range of pressures can be achieved at relatively low operational voltage, even in pure quencher gas at atmospheric pressure (e.g. pure isobutene). The TIP-HOLE structure may be produced by the innovative scalable additive manufacturing technology for large-area, multiple-layer printed circuit boards, recently developed by the UHV technology company (USA) and discussed for the first time in this work.

Synthesis and Assembly of Hepatitis B Virus-Like Particles in a Pichia pastoris Cell-Free System.

Virus-like particles (VLPs) are supramolecular protein assemblies with the potential for unique and exciting applications in synthetic biology and medicine. Despite the attention VLPs have gained thus far, considerable limitations still persist in their production. Poorly scalable manufacturing technologies and inconsistent product architectures continue to restrict the full potential of VLPs. Cell-free protein synthesis (CFPS) offers an alternative approach to VLP production and has already proven to be successful, albeit using extracts from a limited number of organisms. Using a recently developed Pichia pastoris-based CFPS system, we have demonstrated the production of the model Hepatitis B core antigen VLP as a proof-of-concept. The VLPs produced in the CFPS system were found to have comparable characteristics to those previously produced in vivo and in vitro. Additionally, we have developed a facile and rapid synthesis, assembly and purification methodology that could be applied as a rapid prototyping platform for vaccine development or synthetic biology applications. Overall the CFPS methodology allows far greater throughput, which will expedite the screening of optimal assembly conditions for more robust and stable VLPs. This approach could therefore support the characterization of larger sample sets to improve vaccine development efficiency.

Impacts of process-induced porosity on material properties of copper made by binder jetting additive manufacturing

Binder Jetting (BJ) is an efficient, economical, and scalable Additive Manufacturing (AM) technology that can be used in fabricating parts made of reflective and conductive materials like copper, which have applications in advanced thermal and electrical components. The primary challenge of BJ is in producing fully dense, homogeneous parts without infiltration. To this end, copper parts of porosities ranging from 2.7% to 16.4% were fabricated via BJ, by varying powder morphology, post-process sintering, and Hot Isostatic Pressing conditions. The aim of this study is to characterize and quantify the effects of porosity on the material properties of Binder Jet pure copper parts. Copper parts with the lowest porosity of 2.7% demonstrated a tensile strength of 176 MPa (80.2% of wrought strength), a thermal conductivity of 327.9 W/m·K (84.5% that of wrought copper), and an electrical conductivity of 5.6 × 107 S/m (96.6% IACS). The porosity-property relationship in these parts was compared against theoretical and empirical models in the literature for similar structures. These studies contribute towards developing a scientific understanding of the process-property-performance relationship in BJ of copper and other printed metals, which can help in tailoring materials and processing conditions to achieve desired properties.

Optimized Ge1−<italic>x</italic>Sn<italic>x</italic>/Ge Multiple-Quantum-Well Heterojunction Phototransistors for High-Performance SWIR Photodetection

We present the design and analysis of three-terminal Ge1− x Sn x /Ge multiple-quantum-well (MQW) heterojunction phototransistors (HPTs) for high-performance short-wave infrared (SWIR) photodetection. The active layer incorporates Ge1− x Sn x /Ge MQW structures between base–collector junctions pseudomorphically grown on Ge-on-Si substrates, thereby providing compatibility with CMOS platforms for low cost and scalable manufacturing technology. Introducing Sn into the MQW structures can effectively reduce the direct bandgap, thereby considerably extending the photodetection range in the SWIR spectral range with improved absorption efficiencies. In addition, the use of MQW structures as the active layer can enhance the absorption coefficient via quantum-confinement effects, thus further enhancing the photoresponses. We develop theoretical models to calculate the strained electronic band structures and optical absorption coefficients for the Ge1− x Sn x /Ge MQW structures, and the current gain is evaluated as a function of the barrier/well thicknesses, number of periods of the MQW structures, and doping concentrations of the layers for the HPT structures. The calculation results show that the absorption coefficient can be significantly enhanced by increasing the Sn content in the Ge1− x Sn x /Ge MQW active layer, and the current gain can be considerably enhanced by optimizing the HPT structures. With the enhanced absorption coefficient and current gain, high-responsivity photodetection can be achieved in the SWIR spectral range, thus making this device very promising for a wide range of SWIR photodetection applications.

A “cleanroom-free” and scalable manufacturing technology for the microfluidic generation of lipid-stabilized droplets and cell-sized multisomes

There is a growing demand to construct artificial biomimetic structures from the bottom-up using simple chemical components in a controlled and high-throughput way. These cell mimics are encapsulated by lipid membranes and can reconstitute biological machinery within them. To date, such synthetic cells based upon droplet microfluidics are fabricated using non-scalable, expensive and time-consuming strategies, and are thus restricted to small-scale in-house manufacturing. Here, we report a “cleanroom-free” and highly scalable microfluidic manufacturing technology based on dry film resists and multilayer lamination. The technology facilitates the controlled and high-throughput generation of stable and monodisperse droplets using anionic surfactants and more biologically relevant phospholipids. We demonstrate the versatility of this approach by selectively patterning the surface chemistry of the device, enabling the production of compartmentalized lipid structures based on droplet interface bilayers (multisomes). This technology has the potential to simultaneously unlock the widespread exploitation of microfluidics to chemists and synthetic biologists not having access to controlled production environments and facilitate low-cost (< £1) high-volume fabrication of self-contained disposable devices with minimum feature sizes of 30 μm. The associated material and equipment costs approach those of other deskilled prototyping technologies, such as 3D printing that have made the transition into the mainstream.