Cell Force Microscopy on Elastic Layers of Finite Thickness

Rudolf Merkel ^1*, Norbert Kirchgener ¹, Claudia M Cesa ¹ and Bernd Hoffmann ¹

¹ Research Centre Jülich

^* To whom correspondence should be addressed. E-mail: r.merkel{at}fz-juelich.de.

Submitted on April 24, 2007
Revised on May 30, 2007
Accepted on 5 July 2007

	Abstract

Forces applied by cells to substrates can be measured using soft substrates with embedded displacement markers. Traction forces are retrieved from microscopic images by determining the displacements of these markers and fitting the generating forces. Here we show that using elastic films of 5 -- 10 µm thickness one can improve the spatial resolution of the technique. To this end we derived explicit equations for the mechanical response of an elastic layer of finite thickness to point forces. Moreover, these equations allow highly accurate force measurements on eukaryotic cells on films where finite thickness effects are relevant (below ~60 µm).

Key Words: Traction force microscopy, cell forces, elastic substrates, finite layer thickness, lateral resolution

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