A7_Microfluidics_fundamentals_I

Micropumps valveless

electrophoresis of a specific solute

E is field strength, q and r are the charge of the solute, η is the viscosity

electroosmosis of the bulk liquid

σ is the surface charge density of the channels and δ is the Debye double layer thickness, µ’s are the mobilities

Debye length depends on the molarity

M of the electrolyte in the buffer. As the ionic strength (or the number of charged ions increases, the Debye length decreases.

Pressure-driven vs. electroosmotic flow

Voltage-driven flow

Voltage applied at ends of a channel filled with electrically conductive liquid

Multi-layer PDMS-based

LSI platform

The valve (left) can be closed by applying a pressure p to the control channel

Microfluidic realization of a free interface diffusion (FID) protein crystallization assay, based on the large scale integration platform (LSI). One unit cell consists of three crystallization cells for crystallization with different mixing ratios (a). They are initially filled with liquid while the central interface valve is closed (b). Afterwards, the interface valve is opened to allow diffusive mixing between the coupled chambers (c). The chip (d) consists of 48 cells for protein crystallization.

Capillary driven test strips

Droplet based microfluidic platforms

Droplet based microfluidic platforms

Microfluidic realization of a protein crystallization assay, based on the pressure driven droplet-based platform. The protein and precipitation solution are continuously injected into one droplet of adjustable volume (a) and afterwards transported into a glass capillary for crystallization (b). Recirculating flows inside the droplets enhance mixing and induce the crystallization process (c).

Integrated lab-on-a-chip architecture for a colorimetric glucose assay, based on the droplet based electrowetting platform.

Four reservoirs with injection elements are connected to an electrode

circuit, where the droplets are mixed, split and transported to detection sites for readout

Class info

•Microfluidics fundamentals II (A8)

•HW4 – microfluidics– is available in the class homepage – due Sunday, October 13

•Required reading: make sure you read and understand the microfluidics support papers

•This week office hours: 10-12h on Thursday, October 10

•Next week: no formal classes. Visit to INESC MN clean room – please sign-up

•P1 papers expected to be available Sunday, October 13

•A9 and A10 – case studies in biomicrofluidics; target capture in microchannels