Robotic liquid handling and automation in epigenetics

Automated liquid-handling robots and high-throughput screening (HTS) are widely used in the pharmaceutical industry for the screening of large compound libraries, small molecules for activity against disease-relevant target pathways, or proteins. HTS robots capable of low-volume dispensing reduce assay setup times and provide highly accurate and reproducible dispensing, minimizing variation between sample replicates and eliminating the potential for manual error. Low-volume automated nanoliter dispensers ensure accuracy of pipetting within volume ranges that are difficult to achieve manually. In addition, they have the ability to potentially expand the range of screening conditions from often limited amounts of valuable sample, as well as reduce the usage of expensive reagents. The ability to accurately dispense lower volumes provides the potential to achieve a greater amount of information than could be otherwise achieved using manual dispensing technology. With the emergence of the field of epigenetics, an increasing number of drug discovery companies are beginning to screen compound libraries against a range of epigenetic targets. This review discusses the potential for the use of low-volume liquid handling robots, for molecular biological applications such as quantitative PCR and epigenetics.     

Integrated liquid and droplet dielectrophoresis for biochemical assays

Surface microfluidic systems have emerged as an attractive alternative to conventional closed-channel microfluidic devices. In many such systems, electric fields are leveraged for the manipulation and transport of discrete nanoliter droplets on open planar surfaces. The present research work discusses dielectrophoretic liquid and droplet actuations, which provide an attractive methodology for dispensing and manipulating nanoliter and picoliter droplets on planar surfaces. We demonstrate the integration of two independent sample actuation schemes, namely liquid dielectrophoresis (L-DEP) and droplet dielectrophoresis, and furthermore validate its applicability through model biochemical assays (DNA-PicoGreen^® assay and DNA FRET assay). We also describe and present ‘tapering L-DEP’ actuation scheme, whereby we demonstrate how to simultaneously create multiple droplets of different sizes and volumes in the range of nanoliter and picoliters, from a given larger parent sample droplet.     

Automatic liquid handling for life science: a critical review of the current state of the art

Liquid handling plays a pivotal role in life science laboratories. In experiments such as gene sequencing, protein crystallization, antibody testing, and drug screening, liquid biosamples frequently must be transferred between containers of varying sizes and/or dispensed onto substrates of varying types. The sample volumes are usually small, at the micro- or nanoliter level, and the number of transferred samples can be huge when investigating large-scope combinatorial conditions. Under these conditions, liquid handling by hand is tedious, time-consuming, and impractical. Consequently, there is a strong demand for automated liquid-handling methods such as sensor-integrated robotic systems. In this article, we survey the current state of the art in automatic liquid handling, including technologies developed by both industry and research institutions. We focus on methods for dealing with small volumes at high throughput and point out challenges for future advancements.     

The dispensing well plate: a novel device for nanoliter liquid handling in ultra high-throughput screening

A novel method for massive parallel dispensing of liquids in the nanoliter range has been presented. The proposed DWP method has been studied experimentally using prototypes fabricated by different micromachining techniques. Their dispensing performance was successfully characterized by gravimetric and fluorometric experiments. The DWP prototypes were able to deliver fixed volumes between 43 nL and 50 nL, with a CV as low as 1%, when dispensing an array of 24 droplets simultaneously onto a slide and measuring fluorescence with a biochip reader.The proposed DWP method has been proven to be very accurate, scalable, simple, and robust. A reproducibility of the mean dosage volume of better than 3% has been obtained by gravimetric measurements for all prototypes dispensing aqueous solutions or pure DMSO. The DWP technology, therefore, has the potential to speed up the liquid handling in HTS by a factor of 10 to 100 and reduce reagent consumption by a factor of 10 to 20 in the future. The applicability of the DWP method in an HTS laboratory environment has been demonstrated by performing a miniaturized kinase assay with comparable quality to conventional assay volumes. By the demonstrated miniaturization, the reagent consumption could be reduced by a factor of 20.     

An automated, parallel processing approach to biomolecular sample preparation

Sample preparation for DNA and RNA assays is a prime candidate for laboratory automation. A novel, parallel processing device that performs the three separate liquid-handling functions necessary for such sample preparation-dispensing, pipetting, and pressurizing-is presented. The device comprises an array of fine nozzles connected by fluidic channels to automatically and precisely distribute flow between one source and an array of points. The design principles, as well as the experimental and computational methods used to develop the device, are described. Test results, including accuracy, uniformity, volume range, and timing, are presented. The functionality of the device is demonstrated by performing a solid-phase extraction of DNA with two types of microcolumns.     

Collecting Sample Weight Data On Various Liquid Handling Robots

Liquid-handling platforms often do not provide a mechanism for collecting weight data needed for instrument qualification and sample transfer confirmation. This paper discusses the development, implementation, and application of a system that facilitates liquid-handling confirmation required for Good Laboratory Practice (GLP) compliance and provides an avenue to track the amount of sample transferred for extraction.The Balance Data Collector (BDC) system was designed as a flexible generic balance tool to be used with Tecan Gemini© and Packard WinPrep® software. The BDC system provides a user interface for balance configuration, a pointer to a file for storing weight data, and an external interface through command-line arguments. BDC is currently used for instrument qualification and sample collection in bioanalytical applications. Instrument qualification includes refining instrument liquid classes and verifying pipetting accuracy and precision. For bioanalytical applications using 96-well plates, BDC collects individual aliquot weights of samples transferred during an assay.The BDC system provides the user with the capability to control a balance via liquid-handling programming platforms such as Tecan Gemini© and Packard WinPrep®. Integration of liquid-handling platforms and BDC reduces the time the scientist must spend recording weight data needed for GLP compliance and can be used to increase accuracy of calculated sample concentrations.     

Precise droplet volume measurement and electrode-based volume metering in digital microfluidics

In this work, for the first time, we demonstrate nanoscale droplet generation from a continuous electrowetting microchannel using a simple and precise image-based droplet volume metering technique. One of the most popular ways of droplet generation in electrowetting devices is to split a droplet from a preloaded volume as a fluid reservoir. This method is effective, but lowers volume consistency after multiple droplets are generated. Impedance- and capacitance-based methods of volume metering have been successfully used in digital microfluidics, but require complex circuitry and feedback signal processing. In this work, we demonstrate nanoliter droplet generation from a continuous electrowetting channel used as a replenishable fluid reservoir which compensates for the loss of reservoir volume as droplets are sequentially split. This improves volume consistency especially for applications requiring multi-droplet generation. Based on the area of the electrode, the volume of each droplet split from the electrowetting channel can be obtained by a simple and precise image processing technique with no need for additional hardware and measurement errors of ±0.05 %. This simple technique can be used in a wide range of applications that require precise volume metering, such as immunoassay.     

A Piezoactuated Droplet-Dispensing Microfluidic Chip

A microfluidic dispensing device that is capable of generating droplets with volumes varying between 1 nL and 50 pL at an ejection frequency of up to 6 kHz is presented. In this device, a piezoactuator pushes onto an elastic membrane via piston tips; the mechanical bending of the membrane generates a pressure pulse pushing droplets out. An analytical model was developed solving bending characteristics of a plate-actuated fluidic dispensing system and used to calculate the displaced volume. The model was extended to perform stress analysis to find the optimum piston tip radius by minimizing design stresses. The optimum piston tip radius was found to be 67% of the chamber radius. The actuation force estimated using the analytical model was then used as input to a finite element model of the dispenser. A detailed numerical analysis was then performed to model the fluid flow and droplet ejection process and to find critical geometric and operating parameters. Results from both models were used together to find the best design parameters. The device contains three layers, a silicon layer sandwiched between two polydimethylsiloxane (PDMS) polymer layers. Silicon dry etching, together with PDMS soft lithography, was used to fabricate the chip. PDMS oxygen plasma bonding is used to bond the layers. Prototypes developed were successfully tested to dispense same-sized droplets repeatedly without unwanted droplets. The design allows easy expansion and simultaneous dispensing of fluids.$hfill$[2009-0099]      

A framework for developing home automation systems: From requirements to code

This article presents an integrated framework for the development of home automation systems following the model-driven approach. By executing model transformations the environment allows developers to generate executable code for specific platforms. The tools presented in this work help developers to model home automation systems by means of a domain specific language which is later transformed into code for home automation specific platforms. These transformations have been defined by means of graph grammars and template engines extended with traceability capabilities. Our framework also allows the models to be reused for different applications since a catalogue of requirements is provided. This framework enables the development of home automation applications with techniques for improving the quality of both the process and the models obtained. In order to evaluate the benefits of the approach, we conducted a survey among developers that used the framework. The analysis of the outcome of this survey shows which conditions should be fulfilled in order to increase reusability.     

Boston Innovation''s SmartPlate Integrates Laboratory Functions to Increase Efficiency and Flexibility of Drug Discovery

Assay development is often facilitated by testing the chemistry against a representative or focused library of molecular compounds. Boston Innovation Inc. (“BII”), has introduced its SmartPlate technology which integrates molecular compound storage and dispensing in a single tool which enables many assay iterations quickly, easily, and at low cost, while maintaining consistent compound integrity. SmartPlate does this by storing concentrated compounds in 100% DMSO in sealed reservoirs, each with a dedicated dispensing tap. The compounds are never exposed to air, moisture, or light. Risks of cross-contamination and the need for cleaning or disposing pipette tips are eliminated. Compounds are metered and integrally diluted within the dispensing taps using BII's Direct Dilution™ technology, which allows SmartPlate to serve the needs of high density assay platforms with non-contact dispensing from 5 to 200nL of compound directly to standard assay plates. The integration of functions cuts waste, cost, and time from the drug discovery process by maintaining compound integrity, preserving valuable compound inventory, and eliminating process steps. At 15nL compound dispensing, 15μL of each compound in SmartPlate can now theoretically support one thousand assays without revisiting the main compound repository.     

应用于肿瘤细胞基因表达水平分析的微流控芯片

近年来快速发展的微流控技术为单细胞基因诊断的基础研究提供了一个有力的平台,微流控芯片具有样品和试剂低消耗、快速实时、大量样本平行处理等优点,还可以使分析过程自动化、防止污染以及完成自动高效的重复实验。本文主要介绍一种用于高通量单细胞基因表达水平分析的微流控芯片技术平台。芯片集成了单细胞捕获、裂解、纯化、逆转录等生物样品处理单元,通过内置气动微阀实现细胞反应腔的独立寻址,从而实现单细胞处理与分析整个过程的自动化操控。实验结果显示了此平台可以实现基因表达水平稳定性的评估,具有应用于肿瘤早期诊断领域的潜力。     

Flexible, Parameter-Controlled Nanoliter Pipetting on a Tecan xyz Platform

Cost pressure and rising throughput requirements are important drivers for assay miniaturization. Typical examples for the trend “smaller is better” are found in BioChip applications and in High Throughput Screening (HTS), which is evolving from the 96-well standard to high-density microplates with 384, 864, 1536 or more wells. These applications require the automated pipetting of liquids in the submicroliter volume range, a difficult task for traditional automated liquid handling systems based on syringe pumps. Tecan developed a new device for the accurate pipetting of volumes in the nanoliter range. Based on ink-jet printer technology, this device allows the exact control of the volume of the ejected droplets via a set of parameters. The integration of this new technology into Tecan's flexible xyz-platforms allows an easy use of this powerful technology for several applications. Results such as volume range, accuracy and precision are discussed.     

Transfer of low nanoliter volumes between microplates using focused acoustics—automation considerations

Acoustic droplet ejection (ADE) gently and precisely aliquots nanoliter and picoliter liquid volumes without any physical contact with the solution being transferred. The technology is very automation-friendly, as it is compatible with conventional microplates. Focused energy from an acoustic transducer induces droplet ejection into an inverted standard microplate. The commercial system transfers low-nanoliter volumes of dimethyl sulfoxide–dissolved compound libraries and thereby enables cell-based assays to be performed in 1536-well plates.     

Real-time pre-processing system with hardware accelerator for mobile core networks

With the rapidly increasing number of mobile devices being used as essential terminals or platforms for communication, security threats now target the whole telecommunication infrastructure and become increasingly serious. Network probing tools, which are deployed as a bypass device at a mobile core network gateway, can collect and analyze all the traffic for security detection. However, due to the ever-increasing link speed, it is of vital importance to offload the processing pressure of the detection system. In this paper, we design and evaluate a real-time pre-processing system, which includes a hardware accelerator and a multi-core processor. The implemented prototype can quickly restore each encapsulated packet and effectively distribute traffic to multiple back-end detection systems. We demonstrate the prototype in a well-deployed network environment with large volumes of real data. Experimental results show that our system can achieve at least 18 Gb/s with no packet loss with all kinds of communication protocols.     

组态软件与Modbus协议在矿用传感器调校装置中的应用

针对现有的传感器调校装置存在缺乏数据实时显示和处理、自动闭环控制、通信接口功能等问题,提出了一种将组态软件与Modbus通信协议应用于矿用气体传感器调校装置的方法。该方法利用串行口和Modbus通信协议将所调校的传感器通过单片机和上位机相连,可实时控制传感器调校的整个过程,并能动态采集、处理各传感器数据。实际应用表明,该方法实现了矿用气体传感器调校装置的自动化、精确化,保障了煤矿的生产安全。     

A novel polymer microneedle fabrication process for active fluidic delivery

In this article, we explore a new fabrication process for a flexible, all polymer, active fluidic delivery system, incorporating a fusion of laser micromachining and microfabrication techniques as well as rapid prototyping technology. Here, we show selective fluidic delivery from isolated microchannels through an electrochemically driven pumping reaction, demonstrate the dispensing of dose volumes up to 5.5 μl, and evaluate the device’s performance in terms of its delivery speed and ejection efficiency. Finally, we move this work toward an implantable microfluidic drug delivery device by investigating the device’s biocompatibility through a statistical approach that overviews the viability of bovine aortic endothelial cells on polyimide and silicon substrates.     

移动设备上大型三维医学体数据的可视化方法

基于OpenGLES2．0平台,针对移动设备的硬件局限性,文中提出了一种新颖的大型三维体数据模型渲染技术,可以克服这些限制,实现在这些平台上以精细的高分辨率绘制大型三维医学体数据模型。另外,提出了一种软件架构,这种架构使现有的体绘制技术可以更好地应用于移动设备。通过采用不同的体数据模型,以逐渐提高分辨率的方式进行了一组实验,结果证明文中的方法是可行的、健壮的,在性能受限的平台上实现了大型体数据模型的可视化。     

一种机动式指挥自动化系统的实时数据交换软件设计

 机动式指挥自动化系统需与多类型节点对接,要适应不同节点的状态变化,可应用于各种不同环境。实时数据交换是机动式指挥自动化系统信息共享与高效利用的关键技术,但由于该系统使用系统互联设备中不同的硬件平台、网络平台以及数据库等,造成了使用中多种模式并存、数据无法交换等问题。以某设备测量试验任务为背景,在需求分析的基础上,基于动态多线程和组播技术,设计一种应用于机动式指挥自动化系统的实时数据交换软件,该软件可实现多种体制下的协议转换与数据记录,支持设备状态的实时显示,并可按需完成原始数据的变速重演,支持数据分析,取得了良好的试验效果。     

Multidimensional line dispensing of unfilled adhesives

In comparison with competitive joining methods, the joining technology “adhesive bonding”, provides advantages in the low-stress joining of similar and dissimilar material combinations. As far as the micro-range is concerned, this technology is particularly suitable for the joining of hybrid micro-systems made of different materials and featuring complex geometries. The variety of available adhesives allows the adaptation of the process to the specific joining task. If the technology is transferred from the macro-range to the micro-range, the dispensing and application of the requested minimal adhesive volumes is one of the fundamental challenges. The process limits of nowadays-used micro-dispensing systems are characterised by the minimally dispensable adhesive volume and also by the flexibility with regard to the applicable adhesives and dispensable layout. The objective of the research work, which is specified in this paper is the expansion of the process limits up to smaller volumes and also the guarantee of flexible handling and a high-process stability. This has been the motivation for the Welding and Joining Institute of the RWTH Aachen to develop a micro-dispensing unit for spot and linear adhesive application. The unit comprises a positive-displacement dispensing system with integrated adhesive tempering, process gas supply and process optics. A reproducible dispensing process requires the adhesive reservoir to be absolutely free from gas. For this reason, a one-way system has been developed which allows degasification before the actual dispensing process takes place. Different degasification principles have, in this connection, been tested with regard to their achievement potential. The one-way system further reduces expenditure for cleaning, maintaining and setting-up of the unit. The unit allows the determination of the important parameters influencing the line dispensing of unfilled adhesives with a line width of <50 μm.     

Predicting stock index increments by neural networks: The role of trading volume under different horizons

Recent studies show that there is a significant bidirectional nonlinear causality between stock return and trading volume. In this research, we reinforce this statement and the results presented in some earlier literatures and further investigate whether trading volume can significantly improve the prediction performance of neural networks under short-, medium-and long-term forecasting horizons. An application of component-based neural networks is used in forecasting one-step ahead stock index increments. The models are also augmented by the addition of different combinations of indices’ and component stocks’ trading volumes as inputs to form more general ex-ante forecasting models. Neural networks are trained with the data of stock returns and volumes from NASDAQ, DJIA and STI indices. Results indicate that augmented neural network models with trading volumes lead to improvements, at different extents, in forecasting performance under different terms of forecasting horizon. Empirical results indicate that trading volumes lead to modest improvements on the performance of stock index increments prediction under medium-and long-term horizons.