A microfluidic AFM cantilever based dispensing and aspiration platform
MA3 Solutions, Eindhoven, The Netherlands
2 Department of Precision and Microsystems Engineering, Delft University of Technology, Delft, The Netherlands
Accepted: 24 December 2014
Published online: 12 March 2015
We present the development of a microfluidic AFM (atomic force microscope) cantilever-based platform to enable the local dispensing and aspiration of liquid with volumes in the pico-to-femtoliter range. The platform consists of a basic AFM measurement system, microfluidic AFM chip, fluidic interface, automated substrate alignment, external pressure control system and controlled climate near the dispensing area. The microfluidic AFM chip has a hollow silicon dioxide (SiO2) cantilever connected to an on-chip fluid reservoir at one end and a slicon nitride (Si3N4) tip with an aperture on the other end. A 3D printed plastic fluidic interface glued over the on-chip reservoir was used to connect microfluidics and macrofluidics. The fluidics is connected to an external pressure control system ranging from −0.8 bar to 5 bar with 0.1 bar resolution. This pressure range allows dispensing and aspiration of liquids through the cantilever tip aperture. The controlled climate with a temperature control range between 25°C – 40°C and humidity up to 95% near the dispensing area keeps the droplets for sufficiently long time before they evaporate. An array of droplets can be programmed to be dispensed automatically and access them again with a position accuracy of 1 micron. Experiments were performed with two types of cantilevers with different geometrical configurations. A minimum flow rate control of 50 fL/s was obtained and also frequency shift was monitored as the cantilever was filled with liquid. This platform will be used for various chemical and biological applications.
Key words: Microfluidic / Femtoliter / Hollow cantilever / Dispensing / Aspiration / Pressure control system / AFM
© van Oorschot et al.; licensee Springer., 2016
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