In vivo biocompatibility of porous and non-porous polypyrrole based trilayered actuators.

Trilayered polypyrrole (PPy) actuators have high stress density, low modulus and have wide potential biological applications including use in artificial muscles and in limb prosthesis after limb amputation. This article examines the in vivo biocompatibility of actuators in muscle using rabbit models. The actuators were specially designed with pores to encourage tissue in growth; this study also assessed the effect of such pores on the stability of the actuators in vivo. Trilayered PPy actuators were either laser cut with 150 µm pores or left pore-less and implanted into rabbit muscle for 3 days, 2 weeks, 4 weeks and 8 weeks and retrieved subsequently for histological analysis. In a second set of experiments, the cut edges of pores in porous actuator strips were further sealed by PPy after laser cutting to further improve its stability in vivo. Porous actuators with and without PPy sealing of pore edges were implanted intramuscularly for 4 and 8 weeks and assessed with histology. Pore-less actuators incited a mild inflammatory response, becoming progressively walled off by a thin layer of fibrous tissue. Porous actuators showed increased PPy fragmentation and delamination with associated greater foreign body response compared to pore-less actuators. The PPy fragmentation was minimized when the pore edges were sealed off by PPy after laser cutting showing less PPy debris. Laser cutting of the actuators with pores destabilizes the PPy. This can be overcome by sealing the cut edges of the pores with PPy after laser. The findings in this article have implications in future design and manufacturing of PPy actuator for use in vivo.

4D Printing with Mechanically Robust, Thermally Actuating Hydrogels.

A smart valve is created by 4D printing of hydrogels that are both mechanically robust and thermally actuating. The printed hydrogels are made up of an interpenetrating network of alginate and poly(N-isopropylacrylamide). 4D structures are created by printing the "dynamic" hydrogel ink alongside other static materials.

Perceptions of a virtual reality sensory room for adults with neurodevelopmental disabilities.

PURPOSE: Mental ill health and sensory processing difficulties often limit participation in everyday life for adults with neurodevelopmental disabilities. Interventions using technology such as virtual reality (VR) are increasingly accessible and may mitigate these difficulties. Understanding what contributes to the successful implementation of novel interventions is important for future use and evaluation. This study aimed to explore the feasibility of implementing a VR sensory room for adults with neurodevelopmental disabilities, their carers and support staff and to explore future iterations of the product and process. MATERIALS AND METHODS: Thirteen stakeholders who participated in a pilot trial of a VR sensory room were interviewed. Interviews were recorded and transcribed verbatim for thematic analysis. RESULTS: Eleven themes were identified which indicated that adults with neurodevelopmental disabilities found the VR sensory room to be mostly acceptable and enjoyable with usage largely consistent. Individual variation and support requirements were highlighted for each user. Future use may require modifications to the headset, in-built customisation options as well as buy-in and training for support staff. CONCLUSIONS: The VR Sensory room is a promising tool to support adults with neurodevelopmental disabilities and results warrant further scaled research into the impact of this tool on outcomes for adults with disabilities.Implications for RehabilitationWhilst adults with neurodevelopmental disabilities may experience sensory processing difficulties which impact their everyday life, there is a paucity of interventions to address these difficulties.Implementation studies offer the opportunity to explore how evidence-based interventions may be implemented to facilitate the best outcomes.A Virtual Reality Sensory Room may offer an innovative alternative to a traditional sensory room for adults with neurodevelopmental disabilities where implementation is well supported.

Fluidic automation of nitrate and nitrite bioassays in whole blood by dissolvable-film based centrifugo-pneumatic actuation.

This paper demonstrates the full centrifugal microfluidic integration and automation of all liquid handling steps of a 7-step fluorescence-linked immunosorbent assay (FLISA) for quantifying nitrate and nitrite levels in whole blood within about 15 min. The assay protocol encompasses the extraction of metered plasma, the controlled release of sample and reagents (enzymes, co-factors and fluorescent labels), and incubation and detection steps. Flow control is implemented by a rotationally actuated dissolvable film (DF) valving scheme. In the valves, the burst pressure is primarily determined by the radial position, geometry and volume of the valve chamber and its inlet channel and can thus be individually tuned over an extraordinarily wide range of equivalent spin rates between 1,000 RPM and 5,500 RPM. Furthermore, the vapour barrier properties of the DF valves are investigated in this paper in order to further show the potential for commercially relevant on-board storage of liquid reagents during shelf-life of bioanalytical, ready-to-use discs.

Evaluating a virtual reality sensory room for adults with disabilities.

Sensory processing difficulties can negatively impact wellbeing in adults with disabilities. A range of interventions to address sensory difficulties have been explored and virtual reality (VR) technology may offer a promising avenue for the provision of sensory interventions. In this study, preliminary evidence about the impact of Evenness, an immersive VR sensory room experience, for people with disabilities was investigated via a single intervention pre-post mixed methods design. Quantitative methodology included single intervention pre-post design (five month timeframe) with 31 adults with various developmental disabilities to determine the impact of use of aVR sensory room using a head mounted display (HMD) in relation to anxiety, depression, sensory processing, personal wellbeing and adaptive behaviour. Qualitative semi-structured interviews were also conducted with thirteen purposefully selected stakeholders following Evenness use. Results indicated significant improvements in anxiety, depression and sensory processing following Evenness use. Qualitative analysis corroborated the anxiety findings. No significant changes were observed in personal wellbeing or adaptive behaviour. Results are promising and indicate that a VR sensory room may have a positive impact on anxiety, depression and sensory processing for adults with disabilities. A longer study timeframe and a more rigorous experimental methodology is needed to confirm these findings.

Design and fabrication of a COP-based microfluidic chip: chronoamperometric detection of Troponin T.

This work demonstrates the design and fabrication of an all cyclo-olefin polymer based microfluidic device capable of capturing magnetic beads and performing electrochemical detection in a series of gold electrodes. The size of chip is of a microscope slide and features six independent measuring cells for multianalyte detection purposes. The aim of this work is to show that rapid prototyping techniques can be instrumental in the development of novel bioassays, particularly in clinical diagnosis applications. We show the successful determination of troponin-T, a cardiac disease marker, in the clinically relevant range of 0.05-1.0 ng/mL. This methodology achieves a detection limit of 0.017 ng/mL in PBS solutions, and is capable of detecting less than 1 ng/mL in a 1:50 human serum dilution.

The integration of 3D carbon-electrode dielectrophoresis on a CD-like centrifugal microfluidic platform.

We introduce the integration of a novel dielectrophoresis (DEP)-assisted filter with a compact disk (CD)-based centrifugal platform. Carbon-electrode dielectrophoresis (carbon-DEP) refers to the use of carbon electrodes to induce DEP. In this work, 3D carbon electrodes are fabricated using the C-MEMS technique and are used to implement a DEP-enabled active filter to trap particles of interest. Compared to traditional planar metal electrodes, 3D carbon electrodes allow for superior filtering efficiency. The system includes mounting modular 3D carbon-DEP chips on an electrically interfaced rotating disk. This allows simple centrifugal pumping to replace the large footprint syringe pump approaches commonly used in DEP systems. The advantages of the CD setup include not only a reduced footprint, but also complexity and cost reduction by eliminating expensive precision pumps and fluidic interconnects. To demonstrate the viability of this system we quantified the filter efficiency in the DEP trapping of yeast cells from a mix of latex and yeast cells. Results demonstrate selective filtering at flow rates up to 35 microl min(-1). The impact of electrode height, DEP chip misalignment and particle sedimentation on filter efficiency and the advantages this system represents are analyzed. The ultimate goal is to obtain an automated platform for bioparticle sorting with application in different fields such as point-of-care diagnostics and cell-based therapies.

Validation of a centrifugal microfluidic sample lysis and homogenization platform for nucleic acid extraction with clinical samples.

The applications of microfluidic technologies in medical diagnostics continue to increase, particularly in the field of nucleic acid diagnostics. While much attention has been focused on the development of nucleic acid amplification and detection platforms, sample preparation is often taken for granted or ignored all together. Specifically, little or no consideration is paid to the development of microfluidic systems that efficiently extract nucleic acids from biological samples. Here, a centrifugal microfluidic platform for mechanical sample lysis and homogenization is presented. The system performs sample lysis through a magnetically actuated bead-beating system followed by a centrifugal clarification step. The supernatant is then transferred for extraction using a unique siphon. Several other new microfluidic functions are implemented on this centrifugal platform as well, including sample distribution, a unique hydraulic capillary valve, and self-venting. Additionally, the improved system has features with a small footprint designed specifically for integration with further downstream processing steps. Biological validation of the platform is performed using Bacillus subtilis spores and clinical samples (nasopharyngeal aspirates) for respiratory virus detection. The platform was found to be as efficient as in-tube bead-beating lysis and homogenization for nucleic acid extraction, and capable of processing 4 samples in batch to near PCR-ready products in under 6 min.

Centrifugal microfluidics for biomedical applications.

The centrifugal microfluidic platform has been a focus of academic and industrial research efforts for almost 40 years. Primarily targeting biomedical applications, a range of assays have been adapted on the system; however, the platform has found limited commercial success as a research or clinical tool. Nonetheless, new developments in centrifugal microfluidic technologies have the potential to establish wide-spread utilization of the platform. This paper presents an in-depth review of the centrifugal microfluidic platform, while highlighting recent progress in the field and outlining the potential for future applications. An overview of centrifugal microfluidic technologies is presented, including descriptions of advantages of the platform as a microfluidic handling system and the principles behind centrifugal fluidic manipulation. The paper also discusses a history of significant centrifugal microfluidic platform developments with an explanation of the evolution of the platform as it pertains to academia and industry. Lastly, we review the few centrifugal microfluidic-based sample-to-answer analysis systems shown to date and examine the challenges to be tackled before the centrifugal platform can be more broadly accepted as a new diagnostic platform. In particular, fully integrated, easy to operate, inexpensive and accurate microfluidic tools in the area of in vitro nucleic acid diagnostics are discussed.

A simple technique for development of fibres with programmable microsphere concentration gradients for local protein delivery.

Alginate has been a biologically viable option for controlled local delivery of bioactive molecules in vitro and in vivo. Specific bioactive molecule release profiles are achieved often by controlling polymer composition/concentration, which also determines the modulus of hydrogels. This largely limits alginate-mediated bioactive molecule delivery to single-factors of uniform concentration applications, rather than applications that may require (multiple) bioactive molecules delivered at a concentration gradient for chemotactic purposes. Here we report a two-phase PLGA/alginate delivery system composed of protein-laden poly-d,l-lactic-co-glycolic acid (PLGA) microspheres wet-spun into alginate fibres. Fluorescein isothiocyanate-conjugated bovine serum albumin (FITC-BSA) was used as a model protein and the developed structures were characterized. The fabrication system devised was shown to produce wet-spun fibres with a protein concentration gradient (G-Alg/PLGA fibre). The two-phase delivery matrices display retarded FITC-BSA release in both initial and late stages compared to release from the PLGA microspheres or alginate fibre alone. In addition, incorporation of higher concentrations of protein-loaded PLGA microspheres increased protein release compared to the fibres with lower concentrations of BSA-loaded microspheres. The "programmable" microsphere concentration gradient fibre methodology presented here may enable development of novel alginate scaffolds with the ability to guide tissue regeneration through tightly-controlled release of one or more proteins in highly defined spatio-temporal configurations.

Cell compatible encapsulation of filaments into 3D hydrogels.

Tissue engineering scaffolds for nerve regeneration, or artificial nerve conduits, are particularly challenging due to the high level of complexity the structure of the nerve presents. The list of requirements for artificial nerve conduits is long and includes the ability to physically guide nerve growth using physical and chemical cues as well as electrical stimulation. Combining these characteristics into a conduit, while maintaining biocompatibility and biodegradability, has not been satisfactorily achieved by currently employed fabrication techniques. Here we present a method combining pultrusion and wet-spinning techniques facilitating incorporation of pre-formed filaments into ionically crosslinkable hydrogels. This new biofabrication technique allows the incorporation of conducting or drug-laden filaments, controlled guidance channels and living cells into hydrogels, creating new improved conduit designs.

Poly(3,4-ethylenedioxythiophene):dextran sulfate (PEDOT:DS) - a highly processable conductive organic biopolymer.

A novel water-dispersible conducting polymer analogous to poly(3,4-dioxythiophene):polystyrene sulfonate (PEDOT:PSS) has been chemically synthesized in a single reaction in high yield. PEDOT:DS, a new member of the polythiophene family, is composed of a complex between PEDOT and the sulfonated polysaccharide polyanion dextran sulfate. Drop-cast films of aqueous suspensions of the material display a native conductivity of up to 7 ± 1 S cm(-1), increasing to 20 ± 2 S cm(-1) after treatment with ethylene glycol and thermal annealing. Mass ratios of the precursors NaDS and EDOT were varied from 5:1 to 2:1 and a decrease in the NaDS:EDOT ratio produces tougher, less hygroscopic films of higher conductivity. Ultraviolet-visible spectroelectrochemistry yields spectra typical of PEDOT complexes. Cyclic voltammetry reveals that PEDOT:DS is electrochemically active from -1.0 to 0.8 V vs. Ag/Ag(+) in acetonitrile, with similar characteristics to PEDOT:PSS. Water dispersions of PEDOT:DS are successfully processed by drop casting, spray coating, inkjet printing and extrusion printing. Furthermore, laser etching of dried films allows the creation of patterns with excellent definition. To assess the cytotoxicity of PEDOT:DS, L-929 cells were cultured with a polymer complex concentration range of 0.002 to 0.2 g l(-1) in cell culture medium. No significant difference is found between the proliferation rates of L-929 cells exposed to PEDOT:DS and those in plain medium after 96h. However, PEDOT:PSS shows around 25% less cell growth after 4 days, even at the lowest concentration. Taken together, these results suggest PEDOT:DS has exceptional potential as an electromaterial for the biointerface.

3D printing of layered brain-like structures using peptide modified gellan gum substrates.

The brain is an enormously complex organ structured into various regions of layered tissue. Researchers have attempted to study the brain by modeling the architecture using two dimensional (2D) in vitro cell culturing methods. While those platforms attempt to mimic the in vivo environment, they do not truly resemble the three dimensional (3D) microstructure of neuronal tissues. Development of an accurate in vitro model of the brain remains a significant obstacle to our understanding of the functioning of the brain at the tissue or organ level. To address these obstacles, we demonstrate a new method to bioprint 3D brain-like structures consisting of discrete layers of primary neural cells encapsulated in hydrogels. Brain-like structures were constructed using a bio-ink consisting of a novel peptide-modified biopolymer, gellan gum-RGD (RGD-GG), combined with primary cortical neurons. The ink was optimized for a modified reactive printing process and developed for use in traditional cell culturing facilities without the need for extensive bioprinting equipment. Furthermore the peptide modification of the gellan gum hydrogel was found to have a profound positive effect on primary cell proliferation and network formation. The neural cell viability combined with the support of neural network formation demonstrated the cell supportive nature of the matrix. The facile ability to form discrete cell-containing layers validates the application of this novel printing technique to form complex, layered and viable 3D cell structures. These brain-like structures offer the opportunity to reproduce more accurate 3D in vitro microstructures with applications ranging from cell behavior studies to improving our understanding of brain injuries and neurodegenerative diseases.

Three-dimensional printing fiber reinforced hydrogel composites.

An additive manufacturing process that combines digital modeling and 3D printing was used to prepare fiber reinforced hydrogels in a single-step process. The composite materials were fabricated by selectively pattering a combination of alginate/acrylamide gel precursor solution and an epoxy based UV-curable adhesive (Emax 904 Gel-SC) with an extrusion printer. UV irradiation was used to cure the two inks into a single composite material. Spatial control of fiber distribution within the digital models allowed for the fabrication of a series of materials with a spectrum of swelling behavior and mechanical properties with physical characteristics ranging from soft and wet to hard and dry. A comparison with the "rule of mixtures" was used to show that the swollen composite materials adhere to standard composite theory. A prototype meniscus cartilage was prepared to illustrate the potential application in bioengineering.

Comprehensive integration of homogeneous bioassays via centrifugo-pneumatic cascading.

This work for the first time presents the full integration and automation concept for a range of bioassays leveraged by cascading a centrifugo-pneumatic valving scheme to sequentially move several liquids through shared channel segments for multi-step sample preparation into the detection zone. This novel centrifugo-pneumatic liquid handling significantly simplifies system manufacture by obviating the need for complex surface functionalization procedures or hybrid material integration, as it is common in conventional valving methods such as capillary burst valves or sacrificial valves. Based on the centrifugo-pneumatic valving scheme, this work presents a toolkit of operational elements implementing liquid loading/transfer, metering, mixing and sedimentation in a microstructured polymer disc. As a proof of concept for the broad class of homogeneous bioassays, the full integration and automation of a colorimetric nitrate/nitrite test for the detection of clinically relevant nitric oxide (NO) in whole blood is implemented. First, 40 µL of plasma is extracted from a 100 µL sample of human blood, incubated for one hour with the enzymatic mixture (60 µL), and finally reacted with 100 µL of colorimetric (Greiss) reagents. Following just a single loading phase at the beginning of the process, all of these steps are automated through the centrifugo-pneumatic cascade with a high level of flow control and synchronization. Our system shows good correlation with controls up to 50 µM of nitrate, which adequately covers the healthy human range (4 to 45.3 µM).

Fabricating electrodes for amperometric detection in hybrid paper/polymer lab-on-a-chip devices.

We present a novel, low-resource fabrication and assembly method for creating disposable amperometric detectors in hybrid paper-polymer devices. Currently, mere paper-based microfluidics is far from being able to achieve the same level of process control and integration as state-of-the-art microfluidic devices made of polymers. To overcome this limitation, in this work both substrate types are synergistically combined through a hybrid, multi-component/multi-material system assembly. Using established inkjet wax printing, we transform the paper into a profoundly hydrophobic substrate in order to create carbon electrodes which are simply patterned from carbon inks via custom made adhesive stencils. By virtue of the compressibility of the paper substrate, the resulting electrode-on-paper hybrids can be directly embedded in conventional, 3D polymeric devices by bonding through an adhesive layer. This manufacturing scheme can be easily recreated with readily available off-the-shelf equipment, and is extremely cost-efficient and rapid with turn-around times of only a few hours.

Optical sensing system based on wireless paired emitter detector diode device and ionogels for lab-on-a-disc water quality analysis.

This work describes the first use of a wireless paired emitter detector diode device (PEDD) as an optical sensor for water quality monitoring in a lab-on-a-disc device. The microfluidic platform, based on an ionogel sensing area combined with a low-cost optical sensor, is applied for quantitative pH and qualitative turbidity monitoring of water samples at point-of-need. The autonomous capabilities of the PEDD system, combined with the portability and wireless communication of the full device, provide the flexibility needed for on-site water testing. Water samples from local fresh and brackish sources were successfully analysed using the device, showing very good correlation with standard bench-top systems.

Centrifugo-pneumatic valving utilizing dissolvable films.

In this article we introduce a novel technology that utilizes specialized water dissolvable thin films for valving in centrifugal microfluidic systems. In previous work (William Meathrel and Cathy Moritz, IVD Technologies, 2007), dissolvable films (DFs) have been assembled in laminar flow devices to form efficient sacrificial valves where DFs simply open by direct contact with liquid. Here, we build on the original DF valving scheme to leverage sophisticated, merely rotationally actuated vapour barriers and flow control for enabling comprehensive assay integration with low-complexity instrumentation on "lab-on-a-disc" platforms. The advanced sacrificial valving function is achieved by creating an inverted gas-liquid stack upstream of the DF during priming of the system. At low rotational speeds, a pocket of trapped air prevents a surface-tension stabilized liquid plug from wetting the DF membrane. However, high-speed rotation disrupts the metastable gas/liquid interface to wet the DF and thus opens the valve. By judicious choice of the radial position and geometry of the valve, the burst frequency can be tuned over a wide range of rotational speeds nearly 10 times greater than those attained by common capillary burst valves based on hydrophobic constrictions. The broad range of reproducible burst frequencies of the DF valves bears the potential for full integration and automation of comprehensive, multi-step biochemical assay protocols. In this report we demonstrate DF valving, discuss the biocompatibility of using the films, and show a potential sequential valving system including the on-demand release of on-board stored liquid reagents, fast centrifugal sedimentation and vigorous mixing; thus providing a viable basis for use in lab-on-a-disc platforms for point-of-care diagnostics and other life science applications.

Centrifugal microfluidics for cell analysis.

Over the past two decades, centrifugal microfluidic systems have successfully demonstrated their capability for robust, high-performance liquid handling to enable modular, multi-purpose lab-on-a-chip platforms for a wide range of life-science applications. Beyond the handling of homogeneous liquids, the unique, rotationally controlled centrifugal actuation has proven to be specifically advantageous for performing cell and particle handling and assays. In this review we discuss technologies to implement two important steps for cell handling, namely separation and capturing/counting.

Infrared controlled waxes for liquid handling and storage on a CD-microfluidic platform.

A novel active valving technique, whereby paraffin wax plugs in microchannels on a centrifugal microfluidic platform are actuated using focused infrared (IR) radiation is demonstrated in this report. Microchannels were simultaneously or sequentially opened using a stationary IR source by forming wax plugs with similar or differing melting points. The presented wax plugs offer key advantages over current active valving techniques, including a less involved fabrication procedure, a simpler actuation process, and the ability to multiplex experiment with active valves. In addition, a new technique for automated liquid reagent storage and release on the microfluidic disc platform, based on the formation and removal of a wax layer, is demonstrated. Overall, the techniques presented in this report offer novel methods for liquid handling, separation, and storage on the centrifugal microfluidic disc platform.