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Sequential push-pull pumping mechanism for washing and evacuation of an immunoassay reaction chamber on a microfluidic CD platform.

Thio TH, Ibrahim F, Al-Faqheri W, Soin N, Kahar Bador M, Madou M - PLoS ONE (2015)

Bottom Line: However, rotational speed dependency and limited space on a CD are two big obstacles to performing such repetitive filling and siphoning steps.The proposed technique is demonstrated on two CD designs.The two designs and the performance evaluation demonstrate that the technique is simple to implement, reliable, easy to control, and allows for repeated push-pulls and thus filling and emptying of the biosensor chamber.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia; Centre for Innovation in Medical Engineering, Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia; Faculty of Science, Technology, Engineering and Mathematics, INTI International University, Persiaran Perdana BBN, Putra Nilai, 71800 Nilai, Negeri Sembilan, Malaysia.

ABSTRACT
A centrifugal compact disc (CD) microfluidic platform with reservoirs, micro-channels, and valves can be employed for implementing a complete immunoassay. Detection or biosensor chambers are either coated for immuno-interaction or a biosensor chip is inserted in them. On microfluidic CDs featuring such multi-step chemical/biological processes, the biosensor chamber must be repeatedly filled with fluids such as enzymes solutions, buffers, and washing solutions. After each filling step, the biosensor chamber needs to be evacuated by a passive siphoning process to prepare it for the next step in the assay. However, rotational speed dependency and limited space on a CD are two big obstacles to performing such repetitive filling and siphoning steps. In this work, a unique thermo-pneumatic (TP) Push-Pull pumping method is employed to provide a superior alternative biosensor chamber filling and evacuation technique. The proposed technique is demonstrated on two CD designs. The first design features a simple two-step microfluidic process to demonstrate the evacuation technique, while the second design shows the filling and evacuation technique with an example sequence for an actual immunoassay. In addition, the performance of the filling and evacuation technique as a washing step is also evaluated quantitatively and compared to the conventional manual bench top washing method. The two designs and the performance evaluation demonstrate that the technique is simple to implement, reliable, easy to control, and allows for repeated push-pulls and thus filling and emptying of the biosensor chamber. Furthermore, by addressing the issue of rotational speed dependency and limited space concerns in implementing repetitive filling and evacuation steps, this newly introduced technique increases the flexibility of the microfluidic CD platform to perform multi-step biological and chemical processes.

No MeSH data available.


Related in: MedlinePlus

Microfluidic CD layers and demonstration CD designs.(a) Layered fabrication of multi-level 3D microfluidic CDs. (b) A design to demonstrate sequential biosensor chamber pull-evacuation. Liquid bursts from source chamber A1 into biosensor chamber B, then pull-evacuated into waste chamber W, followed by liquid bursting from source chamber A2 into biosensor chamber B, then pull-evacuated into waste chamber W. (c) A design to demonstrate biosensor chamber push-wash and pull-evacuation for an immunoassay. Target antigen in biosensor chamber B is washed off into waste chamber W, followed by the bursting of the blocking solution from source chamber A1 into biosensor chamber B, then rinsed and washed off into waste chamber W, and finally the bursting of flourescent labelled antibody solution from source chamber A2 to biosensor chamber B, then rinsed and double volume washed into waste chamber W
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pone.0121836.g002: Microfluidic CD layers and demonstration CD designs.(a) Layered fabrication of multi-level 3D microfluidic CDs. (b) A design to demonstrate sequential biosensor chamber pull-evacuation. Liquid bursts from source chamber A1 into biosensor chamber B, then pull-evacuated into waste chamber W, followed by liquid bursting from source chamber A2 into biosensor chamber B, then pull-evacuated into waste chamber W. (c) A design to demonstrate biosensor chamber push-wash and pull-evacuation for an immunoassay. Target antigen in biosensor chamber B is washed off into waste chamber W, followed by the bursting of the blocking solution from source chamber A1 into biosensor chamber B, then rinsed and washed off into waste chamber W, and finally the bursting of flourescent labelled antibody solution from source chamber A2 to biosensor chamber B, then rinsed and double volume washed into waste chamber W

Mentions: All microfluidic CDs utilized in this study were fabricated using a 3D CD design consisting of five layers that consist of two distinct functional levels [14]. A top functional level contains the necessary TP features for push-wash and pull-evacuation while the bottom functional level contains the features necessary for the assay. In Fig 2(a) we show how the entire CD consists of 5 layers with three layers made of PolyMethyl MethAcrylate (PMMA) material machined using a Computer Numerical Control (CNC) machine (model VISION 2525, by Vision Engraving and Routing Systems, USA). The three PMMA layers are then bound together using two layers of transparent Pressure Sensitive Adhesives (PSA) material (by FLEXcon, USA). The PSA layers are cut using a Cutting Plotter (model: GCC P2-60 / PUMA II, by GCC, Taiwan). Once all five layers are fabricated, the layers are pressure-bound together using a custom made press roller system. In our previous work [14], similarly fabricated microfluidic CDs were tested to a temperature of up to 80°C (on the surface). For biomedical applications such as immunoassays, the CDs are only heated up to 60°C (on the surface). We estimate each PMMA CD can contain up to 5 sets of microfluidic applications, and can be produced cost effectively at current manufacturing capability.


Sequential push-pull pumping mechanism for washing and evacuation of an immunoassay reaction chamber on a microfluidic CD platform.

Thio TH, Ibrahim F, Al-Faqheri W, Soin N, Kahar Bador M, Madou M - PLoS ONE (2015)

Microfluidic CD layers and demonstration CD designs.(a) Layered fabrication of multi-level 3D microfluidic CDs. (b) A design to demonstrate sequential biosensor chamber pull-evacuation. Liquid bursts from source chamber A1 into biosensor chamber B, then pull-evacuated into waste chamber W, followed by liquid bursting from source chamber A2 into biosensor chamber B, then pull-evacuated into waste chamber W. (c) A design to demonstrate biosensor chamber push-wash and pull-evacuation for an immunoassay. Target antigen in biosensor chamber B is washed off into waste chamber W, followed by the bursting of the blocking solution from source chamber A1 into biosensor chamber B, then rinsed and washed off into waste chamber W, and finally the bursting of flourescent labelled antibody solution from source chamber A2 to biosensor chamber B, then rinsed and double volume washed into waste chamber W
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4390340&req=5

pone.0121836.g002: Microfluidic CD layers and demonstration CD designs.(a) Layered fabrication of multi-level 3D microfluidic CDs. (b) A design to demonstrate sequential biosensor chamber pull-evacuation. Liquid bursts from source chamber A1 into biosensor chamber B, then pull-evacuated into waste chamber W, followed by liquid bursting from source chamber A2 into biosensor chamber B, then pull-evacuated into waste chamber W. (c) A design to demonstrate biosensor chamber push-wash and pull-evacuation for an immunoassay. Target antigen in biosensor chamber B is washed off into waste chamber W, followed by the bursting of the blocking solution from source chamber A1 into biosensor chamber B, then rinsed and washed off into waste chamber W, and finally the bursting of flourescent labelled antibody solution from source chamber A2 to biosensor chamber B, then rinsed and double volume washed into waste chamber W
Mentions: All microfluidic CDs utilized in this study were fabricated using a 3D CD design consisting of five layers that consist of two distinct functional levels [14]. A top functional level contains the necessary TP features for push-wash and pull-evacuation while the bottom functional level contains the features necessary for the assay. In Fig 2(a) we show how the entire CD consists of 5 layers with three layers made of PolyMethyl MethAcrylate (PMMA) material machined using a Computer Numerical Control (CNC) machine (model VISION 2525, by Vision Engraving and Routing Systems, USA). The three PMMA layers are then bound together using two layers of transparent Pressure Sensitive Adhesives (PSA) material (by FLEXcon, USA). The PSA layers are cut using a Cutting Plotter (model: GCC P2-60 / PUMA II, by GCC, Taiwan). Once all five layers are fabricated, the layers are pressure-bound together using a custom made press roller system. In our previous work [14], similarly fabricated microfluidic CDs were tested to a temperature of up to 80°C (on the surface). For biomedical applications such as immunoassays, the CDs are only heated up to 60°C (on the surface). We estimate each PMMA CD can contain up to 5 sets of microfluidic applications, and can be produced cost effectively at current manufacturing capability.

Bottom Line: However, rotational speed dependency and limited space on a CD are two big obstacles to performing such repetitive filling and siphoning steps.The proposed technique is demonstrated on two CD designs.The two designs and the performance evaluation demonstrate that the technique is simple to implement, reliable, easy to control, and allows for repeated push-pulls and thus filling and emptying of the biosensor chamber.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia; Centre for Innovation in Medical Engineering, Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia; Faculty of Science, Technology, Engineering and Mathematics, INTI International University, Persiaran Perdana BBN, Putra Nilai, 71800 Nilai, Negeri Sembilan, Malaysia.

ABSTRACT
A centrifugal compact disc (CD) microfluidic platform with reservoirs, micro-channels, and valves can be employed for implementing a complete immunoassay. Detection or biosensor chambers are either coated for immuno-interaction or a biosensor chip is inserted in them. On microfluidic CDs featuring such multi-step chemical/biological processes, the biosensor chamber must be repeatedly filled with fluids such as enzymes solutions, buffers, and washing solutions. After each filling step, the biosensor chamber needs to be evacuated by a passive siphoning process to prepare it for the next step in the assay. However, rotational speed dependency and limited space on a CD are two big obstacles to performing such repetitive filling and siphoning steps. In this work, a unique thermo-pneumatic (TP) Push-Pull pumping method is employed to provide a superior alternative biosensor chamber filling and evacuation technique. The proposed technique is demonstrated on two CD designs. The first design features a simple two-step microfluidic process to demonstrate the evacuation technique, while the second design shows the filling and evacuation technique with an example sequence for an actual immunoassay. In addition, the performance of the filling and evacuation technique as a washing step is also evaluated quantitatively and compared to the conventional manual bench top washing method. The two designs and the performance evaluation demonstrate that the technique is simple to implement, reliable, easy to control, and allows for repeated push-pulls and thus filling and emptying of the biosensor chamber. Furthermore, by addressing the issue of rotational speed dependency and limited space concerns in implementing repetitive filling and evacuation steps, this newly introduced technique increases the flexibility of the microfluidic CD platform to perform multi-step biological and chemical processes.

No MeSH data available.


Related in: MedlinePlus