A microfluidic AFM cantilever based dispensing and aspiration platform

Ralph van Oorschot; Hector Hugo Perez Garza; Roy J S Derks; Urs Staufer; Murali Krishna Ghatkesar

doi:10.1140/epjti/s40485-014-0012-4

Open Access

This article has an erratum: [https://doi.org/10.1140/epjti/s40485-016-0031-4]

EPJ Techn Instrum (2015) 2: 4
https://doi.org/10.1140/epjti/s40485-014-0012-4

Research article

A microfluidic AFM cantilever based dispensing and aspiration platform

Ralph van Oorschot¹^*, Hector Hugo Perez Garza², Roy J S Derks¹, Urs Staufer² and Murali Krishna Ghatkesar²^**

¹ MA3 Solutions, Eindhoven, The Netherlands
² Department of Precision and Microsystems Engineering, Delft University of Technology, Delft, The Netherlands

^* e-mail: r.vanoorschot@ma3solutions.com
^** e-mail: m.k.ghatkesar@tudelft.nl

Received: 17 June 2014
Accepted: 24 December 2014
Published online: 12 March 2015

Abstract

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

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.