Anstey, United Kingdom
Anstey, United Kingdom

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Santaniello T.,University of Milan | Santaniello T.,Loughborough University | Yan Y.,University of Milan | Tocchio A.,Fondazione Filarete | And 13 more authors.
Journal of Micromechanics and Microengineering | Year: 2015

We present a multilayer microfluidic system having a KrF excimer laser micro-patterned thermo-responsive poly-(N-isopropyl)-acrylamide (PNIPAAm) based hydrogel layer integrated as a freestanding component that operates as a temperature-triggered cell isolation actuator for single cell assays applications. When the system is assembled, the size of the laser machined micro-through-hole (entrance diameter is 150 μm, while exit hole diameter varies from 10 to 80 μm) can be reversibly modulated as a consequence of the polymer volumetric phase transition induced by heating the device above the critical temperature of 32 °C; as a result of the polymer water loss, the shrinkage of the layer caused the hole to homogeneously shrink, thus reducing its original size to about 40% in the polymer collapsed state. This actuation mechanism was exploited to trap a cellular sample in the shrunken exit hole on the top of the hydrogel layer by applying a negative pressure across the film when the system is brought to 37 °C. Subsequently, the funneling of the trapped cell took place through the orifice when the polymer's natural relaxation at room temperature toward its initial state occurred; the functionality of the device was proved using optical microscopy to monitor MG63 cells as a model cell line during the funneling through the size-modulating structure. © 2015 IOP Publishing Ltd.

Zhao W.,Loughborough University | Santaniello T.,Loughborough University | Santaniello T.,University of Milan | Webb P.,Manufacturing Technology Center Mtc | And 3 more authors.
Proceedings - Electronic Components and Technology Conference | Year: 2012

We present a compression based packaging technique which can be applied to reversibly seal hydrogel based materials' thin films and micro-fabricated thermoplastic components for hybrid materials stacking microfluidic cells-based chips design. A multilayer microdevice has been realized for liquid leakage tests at the thermoplastic/hydrogel interface nearby the fluidic circuits machined on the plastic layer; biocompatible Poly-hydroxyethylmethacrylate (PHEMA) hydrogel membranes with different thickness (Ranging from 100 to 200 μm) and micro-milled Polymethylmethacrylate components were chosen to realize the chip. By promoting continuous perfusion of the system pumping aqueous coloured dye solutions in the microchannels, the sealing between the two materials resulted guaranteed for tested flow rate values, ranging from 100nL/min to 10mL/min. Furthermore, to take the hydrogel into operation, a representative case study of a micro-bioreactor based on joint hybrid materials and employing PHEMA thin film as a cell culture substrate has been analyzed and modelled by mean of numerical simulation. © 2012 IEEE.

Santaniello T.,University of Milan | Santaniello T.,Loughborough University | Martello F.,Fondazione Filarete | Tocchio A.,Fondazione Filarete | And 7 more authors.
Journal of Micromechanics and Microengineering | Year: 2012

We report a novel reliable and repeatable technologic manufacturing protocol for the realization of micro-patterned freestanding hydrogel layers based on thermo-responsive poly-(N-isopropyl)acrylamide (PNIPAAm), which have potential to be employed as temperature-triggered smart surfaces for cells-on-chip applications. PNIPAAm-based films with controlled mechanical properties and different thicknesses (100-300m thickness) were prepared by injection compression moulding at room temperature. A 9×9 array of 20m diameter through-holes is machined by means of the KrF excimer laser on dry PNIPAAm films which are physically attached to flat polyvinyl chloride (PVC) substrates. Machining parameters, such as fluence and number of shots, are optimized in order to achieve highly resolved features. Micro-structured freestanding films are then easily obtained after hydrogels are detached from PVC by gradually promoting the film swelling in ethanol. In the PNIPAAm water-swollen state, the machined holes diameter approaches a slight larger value (30m) according to the measured hydrogel swelling ratio. Thermo-responsive behaviour and through-hole tapering characterization are carried out by metrology measurements using an optical inverted and confocal microscope setup, respectively. After the temperature of freestanding films is raised above 32°C, we observe that the shrinkage of the whole through-hole array occurs, thus reducing the holes diameter to less than a half its original size (about 15m) as a consequence of the film dehydration. Different holes diameters (10 and 30m) are also obtained on dry hydrogel employing suitable projection masks, showing similar shrinking behaviour when hydrated and undergone thermo-response tests. Thermo-responsive PNIPAAm-based freestanding layers could then be integrated with other suitable micro-fabricated thermoplastic components in order to preliminary test their feasibility in operating as temperature- activated components in the frame of the development of microfluidic devices in multilayer hybrid materials. © 2012 IOP Publishing Ltd.

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