Gradient Microfluidics

Gradient microfluidics for fast generation of molecule, particle, and cell gradients.


Gradients generated by rapid flow and flow reversal. (a) simulation of chemical gradient, and experiments (b) FITC-dextran, (c) cells and (d) 5 μm beads.

Digital coding of biomimetic microfibers


a, Schematic of the digital control steps for the microfluidic spinning chip for serial, parallel and mixed coding with various composite solutions (R, alginate solution with red fluorescent polystyrene beads; G, green; B, blue). b, Mixed coding (serial and parallel) of a fibre. c, Serially coded fibre (inset, serially coded fibre on the microscale). d, Parallel coding of fibres. Scale bars, 200 μm (d), 400 μm (c, inset) and 1 mm (b,c).


Stem cell gel microarray for high throughput analysis


(a) A robotic microarray spotter was used to rapidly print droplets consisting of hMSCs, gelatin methacrylate (GE)-based prepolymer solution and various ECM proteins on TMSPMA functionalized glass slide. The printing step was followed by a 15 sec UV light exposure to form the miniaturized cell-laden constructs. Following printing, cell-laden gel microarrays were placed inside sealed chambers (Illustration made by Jeffrey Aarons). (b) Various combinations of ECM proteins and media formulations were used to conduct the microarrays experiments. The concentration of LN and FN was selected to be 40 μg/ml while OCN was printed at two concentrations of 20 μg/ml and 40 μg/ml. (c) Fluorescence images of the encapsulated proteins within the hydrogel constructs after 24 hours in solution. (d) hMSCs viability within 48 combinatorial 3D microenvironments in normal (control) media after 7 days of culture along with color-diagram displaying the quantified cell viability (n = 3–9).

Flexible electronics for real-time monitoring of biological parameters


Fabrication and characterizations of PGS-PCL substrate-based electronics. (a) Schematic of the electrospinning setup used for fabricating sheets with uniform thickness (i,ii) and fabricating a conductive pattern by screen printing of silver ink on a substrate using a shadow mask (iii). (b) Representative SEM images of typical PGS-PCL electrospun sheets (with the ratio of 1:1), low magnification (i) and high magnification (ii). (c) A representative image of patterned electrospun sheet with a zoomed in micrograph showing the preservation of the PGS-PCL microstructure after the patterning process. (d) Representative strain-stress curves for a typical PGS-PCL electrospun sheet and a sheet containing a conductive pattern. (e) Electrical resistance of different patterns that indicates repeatability of the pattern formation on the surface of electrospun sheet (at least n = 6 independent measurements).


The organs-on-a-chip platforms seek to recapitulate human organ functions at microscale by integrating microfluidic networks with three-dimensional tissue models, which are expected to provide robust and accurate predictions of drug/toxin effects in human bodies. We are developing the most state-of-art organs-on-a-chip platforms with integrated bioreactors containing human tissue constructs and on-line sensors for real-time monitoring of both physical and biochemical parameters of the organoids. Our efforts represent a step towards animal-free testing of drug candidates. We are also exploring advanced data communication technologies such as wireless data transmission and Android Wear.



Microfluidic chip for automated detection of biomarkers from bioreactors containing human organoids.