Generation of micro-sized PDMS particles by a flow focusing technique for biomicrofluidics applications

Abstract

Polydimethylsiloxane (PDMS), due to its remarkable properties, is one of the most widely used polymers in many industrial and medical applications. In this work, a technique based on a flow focusing technique is used to produce PDMS spherical particles with sizes of a few microns. PDMS precursor is injected through a hypodermic needle to form a film/reservoir over the needle's outer surface. This film flows towards the needle tip until a liquid ligament is steadily ejected thanks to the action of a coflowing viscous liquid stream. The outcome is a capillary jet which breaks up into PDMS precursor droplets due to the growth of capillary waves producing a micrometer emulsion. The PDMS liquid droplets in the solution are thermally cured into solid microparticles. The size distribution of the particles is analyzed before and after curing, showing an acceptable degree of monodispersity. The PDMS liquid droplets suffer shrinkage while curing. These microparticles can be used in very varied technological fields, such as biomedicine, biotechnology, pharmacy, and industrial engineering. V C 2016 AIP Publishing LLC.

Flexible PDMS microparticles to mimic RBCs in blood particulate analogue fluids

“…Recent microfluidic and micro-electro-mechanical systems (MEMS) have demonstrated that the high elasticity (flexibility) of polydimethylsiloxane (PDMS) offers unique advantages over more traditional rigid substrate materials such as glass and harder polymers [1,4] . Thus, PDMS has become the most widely used siliconbased organic polymer due to its unique mechanical and optical properties, and is generally considered inert, non-toxic and non-flammable, among other characteristics [3,[5][6][7] . Its applications range from contact lenses and medical devices to shampoos, caulking, lubricating oils and heat-resistant tiles [3,6] .…”

“…Droplet generation may be driven using active methods such as piezoelectric actuators and electric fields [15][16][17] , but monodisperse droplets are most commonly formed in continuous pressuredriven nozzles with flow-focusing or co-flowing method [7,16,[18][19][20] , or T-junction techniques [21][22][23] . Jian et al [24] and Muñoz-Sánchez et al [7] proposed a flow-focusing technique where a PDMS precursor was dispersed into microdroplets within a continuous phase.…”

“…Droplet generation may be driven using active methods such as piezoelectric actuators and electric fields [15][16][17] , but monodisperse droplets are most commonly formed in continuous pressuredriven nozzles with flow-focusing or co-flowing method [7,16,[18][19][20] , or T-junction techniques [21][22][23] . Jian et al [24] and Muñoz-Sánchez et al [7] proposed a flow-focusing technique where a PDMS precursor was dispersed into microdroplets within a continuous phase. Stiffness and deformability are particle characteristics that have gained increasing interest, for example, the reversible deformability found in vivo for the red blood cells (RBCs) plays an important role in blood rheology for vessels with diameters smaller than 300 μm, where the effective viscosity gets reduced due to RBCs migration to the vessel centre, resulting in the formation of a cell-free layer close to the vessels or microdevices walls [25][26][27][28][29] .…”

In vitro particulate analogue fluids for experimental studies of rheological and hemorheological behavior of glucose-rich RBC suspensions

“…Note that the particles used in the literature for similar studies 34,38,39,41 are rigid or semi-rigid and larger; this is an important issue regarding the development of two-phase analogue fluids because it is extremely difficult to develop deformable micron-sized particles in a considerable quantity to make blood analogue fluids. By using a flow focusing technique, Munoz-Sanchez et al 51 were able to produce a limited amount FIG. 3.…”

Microfluidic tools toward industrial biotechnology

“…Within the 24 publications cited by this literature search for microfluidics applied to industrial biotechnology: seven of them are patents related to microfluidic devices for the chemical, pharmaceutical, and biotechnological industries; two are conference articles about biosensors, and another six articles involve mass flow sensor, nanoimprint lithography, perspectives for microalgae exploitation and marine biotechnology, generation of PDMS microparticles, or liposomes . Therefore, it remains only nine publications regarding industrial biotechnology, specially involving cells separation systems, microbioreactors, enzymatic reactions, bacterial culture, capillary systems for fluid treatment, techniques for biological applications, and, finally, a review concerning bioproduction systems …”