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Described here is a novel arrangement of electronically-actuated wax valves for “Lab-on-a-Disc” (LoaD) centrifugal microfluidic platforms. A LoaD platform, with an integrated silver screen-printed layer, operates via a battery-powered electronic system connected to a pattern of electrical leads which is screen printed on a PET layer. The disc also incorporates an array of composite paraffingraphite wax valves which are opened using wirelessly-triggered Ohmic heating.

Cyclic peptide cyanobacterial toxins, in particular Microcystis aeruginosa, pose a serious health risk to humans and animals alike [1], [2]. Occurring mostly in fresh and brackish water, they have been identified to cause cancer promotion and liver damage [3]. Herein, we describe a portable, microfluidic-based system for in-situ detection of algal toxins in fresh water. The technology development presented here is a fully integrated and portable sample-to-answer centrifugal microfluidics-based system for the detection of toxic cyanobacteria – Microcystin-LR in fresh water. Our unique system employs highly-specific recombinant chicken anti-microcystin antibodies, prepared in-house, with a 3D-printed ‘LASER-photo¬diode’ fluorescent detection technique, also developed in-house. The system has high analytical specificity and sensitivity for detection of toxins below the regulatory limit with intra/inter day coefficient of variation of less than 20%. Dissolvable-film based valving technique was used for flow actuation and integration of multiple assays on the centrifugal cartridge. This new approach forms the basis of a cost efficient, USB-controlled water quality monitoring system. Technically, this integrated system consists of two components; a microfluidic disc (figure 1.A), the disc-holder fabricated and assembled from a 3D-printed casing, with electronic components housed in device. The 5-layered microfluidic disc consists of five reservoirs (figure 1.B), each with a separate venti-lation, aligned radially with inter-connected microchannels. A competitive immunoassay format is utilised to detect free toxin (figure 1.C). Sensitivity, reproducibility and ease-of-use are key features of this monitoring device. The ‘top-down’ optical detection system has been modified for improved detection sensitivity, as well as the elimination of external noise.

Infections of high-risk strains of human papilloma virus (HPV16-E7) have been directly linked with cervical carcinogenesis [1]. Despite pervasive HPV testing and vaccinations, resource-poor regions continue to be affected. We present here a fully automated, bead-based Rapid Antigenic Protein In-situ Display (RAPID) Enzyme Linked Immunosorbent Assay (ELISA) for the detection of the onco-proteins of HPV16 E7 [1]. Advanced centrifugal flow control is implemented by a novel router based on lipophilic membranes in an event-trigger valving architecture [2]. By simply replacing the charge of RAPID-functionalized beads in the incubation chamber, the system may be customized for the detection of other biomarkers.

There is increasing evidence that, in addition to their presence, the propensity of circulating tumour cells to form multi-cellular clusters bears significant information about both cellular resistance to chemotherapy and overall prognosis. We present a novel two-stage, stopped-flow, continuous centrifugal sedimentation strategy to measure the size distributions of events (defined here as cells or clusters thereof) in a blood sample. After off-chip removal of red blood cells, healthy white blood cells are sequestered by negative-immunocapture. The purified events are then resolved along a radially inclined rail featuring a series of gaps with increasing width, each connected to a designated outer collection bin. The isolation of candidate events independent of target-specific epitopes is successfully demonstrated for HL60 (EpCAM positive) and sk-mel28 (EpCAM negative) cells using identical protocols and reagents. The propensity to form clusters was quantified for a number of cell lines, showing a negligible, moderate or elevated tendency towards cluster formation. We show that the occupancy distribution of the collection bins closely correlates with the range of cluster sizes intrinsic to the specific cell line.

Cyclic peptide cyanobacterial toxins, in particular Microcystis aeruginosa, pose a serious health risk to humans and animals alike [1], [2]. Occurring mostly in fresh and brackish water, they have been identified to cause cancer promotion and liver damage [3]. Herein, we describe a portable, microfluidic-based system for in-situ detection of algal toxins in fresh water. The Atalanta system is a novel, portable and sample-to-answer platform for the detection of toxic cyanobacteria – Microcystin-LR in fresh water. Atalanta utilises the partnership of highly-specific recombinant chicken anti-microcystin antibodies, prepared in-house, with a 3D-printed ‘LASER-photo¬diode’ fluorescent detection method, also developed in-house. A competitive immunoassay format is utilised to detect free toxin. Furthermore, dissolvable-film (DF) based flow-actuation facilitates full assay inte¬gration. This new approach will form the basis of a cost efficient, USB-controlled water quality monitoring system. The Atalanta detection system consists of two components; the microfluidic Atalanta disc and the disc-holder. The Atalanta disc-holder was fabricated and assembled from a 3D-printed casing, with electronic components housed in device. The 5-layered microfluidic disc consists of five reservoirs, each with a separate venti¬lation, aligned radially with inter-connected microchannels. Each reservoir represents a functional assay step. First, microcystin conjugate is coated to the functionalised surface of the reservoir 3 prior to assembling the disc. A freshwater sample in reservoir 1 is pre-incubated with recombinant antibodies labelled with fluorophore (Alexa 647) in reservoir 2. This is then spun into reservoir 3 for detection through a competitive immunoassay using Microcystin-LR. Low fluorescence signal indicates high Microcystin-LR concentration in the sample.

In addition detecting circulating tumour cells (CTCs) in blood, the presence of multi-cellular clusters has recently been identified to carry further information pertaining to patient outcome. We present a label-free method of measuring the range and load of clusters in a blood sample using a size-exclusion rail operated by centrifugal microfluidics. A negative selection strategy first enriches clusters from a whole blood sample; these clusters are then processed along the rail where they resolve to a series of collection bins according to size. Analysis of the occupancy of these bins then provides metrics on the cancer-cell load carried in the blood.

Mortality rates of up to 50% have been reported after liver failure due to drug-induced hepatotoxicity and certain viral infections(Gao et al. 2008). These adverse conditions frequently affect HIV and tuberculosis patients on regular medication in resource-poor settings. Here, we report full integration of sample preparation with read-out of a 5-parameter liver assay panel (LAP) on a portable, easy-to-use, fast and cost- efficient centrifugal microfluidic analysis system (CMAS). Our unique, dissolvable-film based centrifugo- pneumatic valving was employed to provide sample-to-answer fashion automation for plasma extraction (from finger-prick of blood), metering and aliquoting into separate reaction chambers for parallelized colorimetric quantification during rotation. The entire LAP completes in less than 20 minutes while using only a tenth the reagent volumes when compared with standard hospital laboratory tests. Accuracy of in-situ liver function screening was validated by 96 separate tests with an average coefficient of variance (CV) of 7.9% compared to benchtop and hospital lab tests. Unpaired two sample statistical t-tests were used to compare the means of CMAS and benchtop reader, on one hand; and CMAS and hospital tests on the other. The results demonstrate no statistical difference between the respective means with 94% and 92% certainty of equivalence, respectively. The portable platform thus saves significant time, labour and costs compared to established technologies, and therefore comply with typical restrictions on lab infrastructure, maintenance, operator skill and costs prevalent in many field clinics of the developing world. It has been successfully deployed in a centralised lab in Nigeria.

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.

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. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

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.

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.