Planar digital nanoliter dispensing system based on thermocapillary actuation

We provide guidelines for the design and operation of a planar digital nanodispensing system based on thermocapillary actuation. Thin metallic microheaters embedded within a chemically patterned glass substrate are electronically activated to generate and control 2D surface temperature distributions which either arrest or trigger liquid flow and droplet formation on demand. This flow control is a consequence of the variation of a liquid’s surface tension with temperature, which is used to draw liquid toward cooler regions of the supporting substrate. A liquid sample consisting of several microliters is placed on a flat rectangular supply cell defined by chemical patterning. Thermocapillary switches are then activated to extract a slender fluid filament from the cell and to divide the filament into an array of droplets whose position and volume are digitally controlled. Experimental results for the power required to extract a filament and to divide it into two or more droplets as a function of geometric and operating parameters are in excellent agreement with hydrodynamic simulations. The capability to dispense ultralow volumes onto a 2D substrate extends the functionality of microfluidic devices based on thermocapillary actuation previously shown effective in routing and mixing nanoliter liquid samples on glass or silicon substrates

Bioadditive manufacturing of hybrid tissue scaffolds for controlled release kinetics

Development of engineered tissue scaffolds with superior control over cell-protein interactions is still very much infancy. Advancing through heterogeneous multifold scaffolds with controlled release fashion enables synchronization of regenerating tissue with the release kinetics of loaded biomolecules. This might be an engineering challenge and promising approach for improved and efficient tissue regeneration. The most critical limitations: the selection of proper protein(s) incorporation, and precise control over concentration gradient and timing should be overcome. Hence, tissue scaffolds need to be fabricated in a way that proteins or growth factors should be incorporated and released in a specific spatial and temporal orientation to mimic the natural tissue regeneration process. Spatial and temporal control over heterogeneous porous tissue scaffolds can be achieved by controlling two important parameters: (i) internal architecture with enhanced fluid transport, and (ii) distribution of scaffold base material and loaded modifiers. In this research, heterogeneous tissue scaffolds are designed considering both the parameters. Firstly, the three-dimensional porous structures of the scaffold are geometrically partition into functionally uniform porosity regions and controlled spatial micro-architecture has been achieved using a functionally gradient porosity function. The bio-fabrication of the designed internal porous architecture has been performed using a single nozzle bioadditive manufacturing system. The internal architecture scheme is developed to enhance fluid transport with continuous base material deposition Next, the hybrid tissue scaffolds are modeled with varying material characteristics to mediate the release of base material and enclosed biological modifiers are proposed based on tissue engineering requirements. The hybrid scaffolds are fabricated for spatial control of biomolecules and base material to synchronize the release kinetics with tissue regeneration. A pressure-assisted multi-chamber single nozzle bioadditive manufacturing system is used to fabricate hybrid scaffolds

Single Substrate Electromagnetic Actuator

A microvalve which utilizes a low temperature ( <300° C.) fabrication process on a single substrate. The valve uses buckling and an electromagnetic actuator to provide a relatively large closing force and lower power consumption. A buckling technique of the membrane is used to provide two stable positions for the membrane, and to reduce the power consumption and the overall size of the microvalve. The use of a permanent magnet is an alternative to the buckled membrane, or it can be used in combination with the buckled membrane, or two sets of micro-coils can be used in order to open and close the valve, providing the capability for the valve to operate under normally opened or normally closed conditions. Magnetic analysis using ANSYS 5.7 shows that the addition of Orthonol between the coils increases the electromagnetic force by more than 1.5 times. At a flow rate of 1 mL/m, the pressure drop is < 100 Pa. The maximum pressure tested was 57 kPa and the time to open or close the valve in air is under 100 ms. This results in an estimated power consumption of 0.1 mW.Georgia Tech Research Corp

3D hybrid wound devices for spatiotemporally controlled release kinetics

This paper presents localized and temporal control of releasekinetics over 3-dimensional (3D) hybridwounddevices to improve wound-healing process. Imaging study is performed to extract wound bed geometry in 3D. Non-Uniform Rational B-Splines (NURBS) based surface lofting is applied to generate functionally graded regions. Diffusion-based releasekinetics model is developed to predict time-based release of loaded modifiers for functionally graded regions. Multi-chamber single nozzle solid freeform dispensing system is used to fabricate wounddevices with controlled dispensing concentration. Spatiotemporal control of biological modifiers thus enables a way to achieve target delivery to improve wound healing

Deterministic bead-in-droplet ejection utilizing an integrated plug-in bead dispenser for single bead-based applications

This paper presents a deterministic bead-in-droplet ejection (BIDE) technique that regulates the precise distribution of microbeads in an ejected droplet. The deterministic BIDE was realized through the effective integration of a microfluidic single-particle handling technique with a liquid dispensing system. The integrated bead dispenser facilitates the transfer of the desired number of beads into a dispensing volume and the on-demand ejection of bead-encapsulated droplets. Single bead-encapsulated droplets were ejected every 3 s without any failure. Multiple-bead dispensing with deterministic control of the number of beads was demonstrated to emphasize the originality and quality of the proposed dispensing technique. The dispenser was mounted using a plug-socket type connection, and the dispensing process was completely automated using a programmed sequence without any microscopic observation. To demonstrate a potential application of the technique, bead-based streptavidin-biotin binding assay in an evaporating droplet was conducted using ultralow numbers of beads. The results evidenced the number of beads in the droplet crucially influences the reliability of the assay. Therefore, the proposed deterministic bead-in-droplet technology can be utilized to deliver desired beads onto a reaction site, particularly to reliably and efficiently enrich and detect target biomolecules.112Ysciescopu

A Protocol Generator Tool for Automatic In-Vitro HPV Robotic Analysis

Human Papilloma Virus (HPV) could develop precancerous lesions and invasive cancer, as it is the main cause of nearly all cases of cervical cancer. There are many strains of HPV and current vaccines can only protect against some of them. This makes the detection and genotyping of HPV a research area of utmost importance. Several biomedical systems can detect HPV in DNA samples; however, most of them do not have a procedure as fast, automatic or precise as it is actually needed in this field. This manuscript presents a novel XML-based hierarchical protocol architecture for biomedical robots to describe each protocol step and execute it sequentially, along with a robust and automatic robotic system for HPV DNA detection capable of processing from 1 to 24 samples simultaneously in a fast (from 45 to 162 min), efficient (100% markers effectiveness) and precise (able to detect 36 different HPV genotypes) way. It includes an efficient artificial vision process as the last step of the diagnostic.FIDETIA P055-12/E03Ministerio de Economía y Competitivida TEC2016-77785-

Automated robotic liquid handling assembly of modular DNA devices

Recent advances in modular DNA assembly techniques have enabled synthetic biologists to test significantly more of the available "design space" represented by "devices" created as combinations of individual genetic components. However, manual assembly of such large numbers of devices is time-intensive, error-prone, and costly. The increasing sophistication and scale of synthetic biology research necessitates an efficient, reproducible way to accommodate large-scale, complex, and high throughput device construction. Here, a DNA assembly protocol using the Type-IIS restriction endonuclease based Modular Cloning (MoClo) technique is automated on two liquid-handling robotic platforms. Automated liquid-handling robots require careful, often times tedious optimization of pipetting parameters for liquids of different viscosities (e.g. enzymes, DNA, water, buffers), as well as explicit programming to ensure correct aspiration and dispensing of DNA parts and reagents. This makes manual script writing for complex assemblies just as problematic as manual DNA assembly, and necessitates a software tool that can automate script generation. To this end, we have developed a web-based software tool, http://mocloassembly.com, for generating combinatorial DNA device libraries from basic DNA parts uploaded as Genbank files. We provide access to the tool, and an export file from our liquid handler software which includes optimized liquid classes, labware parameters, and deck layout. All DNA parts used are available through Addgene, and their digital maps can be accessed via the Boston University BDC ICE Registry. Together, these elements provide a foundation for other organizations to automate modular cloning experiments and similar protocols. The automated DNA assembly workflow presented here enables the repeatable, automated, high-throughput production of DNA devices, and reduces the risk of human error arising from repetitive manual pipetting. Sequencing data show the automated DNA assembly reactions generated from this workflow are ~95% correct and require as little as 4% as much hands-on time, compared to manual reaction preparation

Development of an iodine generator for reclaimed water purification in manned spacecraft applications

A successful 30-day test is described of a prototype Iodine Generating and Dispensing System (IGDS). The IGDS was sized to iodinate the drinking water nominally consumed by six men, 4.5 to 13.6 kg (10 to 30 lb) water per man-day with a + or - 10 to 20% variation with iodine (I2) levels of 0.5 to 20 parts per million (ppm). The I2 treats reclaimed water to prevent or eliminate microorganism contamination. Treatment is maintained with a residual of I2 within the manned spacecraft water supply. A simplified version of the chlorogen water disinfection concept, developed by life systems for on-site generation of chlorine (Cl2), was used as a basis for IGDS development. Potable water contaminated with abundant E. Coliform Group organisms was treated by electrolytically generated I2 at levels of 5 to 10 ppm. In all instances, the E. coli were eliminated