Fig. 1 – MicroSquisher – Micro-Scale Compression System. Click on the image to see a larger version.

Micro-Scale Material Characterization

The MicroSquisher can be used to determine the compressive stress-strain properties of a variety of materials with peak forces ranging from 1μN to 1mN.  The device can perform displacement-controlled compression and stress relaxation testing.

Fig. 2 - Force-time curve for a stress relaxation test performed on a 2000μm cube of gelatin with an initial compression of 400μm.

Fig. 4 - Force-time curve for the aggregate compression test shown above. This aggregate was squished from its original diameter of 300μm to a height of 200μm and held for 8 minutes. The force decay is due to the pressure drop within the aggregate due to cell rearrangement.

Cell Aggregate Compression Testing

The tensions that exist along cell-cell boundaries and cell-medium interfaces play an important role in the organization of cells within aggregates [1]. These properties can be determined by compressing a spherical aggregate of cells between parallel plates and measuring the force-time curve that results [2].  In addition to this data, the MicroSquisher image analysis module allows the aggregate profile to be quantified.  In suitably-designed experiments, the geometric and force data provided by the MicroSquisher allows cell-cell interfacial tensions and cell-medium surface tensions to be determined.

(a)	(b)

Fig. 2 - Compressed aggregate of embryonic Zebrafish cells.  (a) shows the uncompressed aggregate positioned between the lower platen and the upper platen.  (b) shows the compressed aggregate with a graphical overlay generated by the image analysis module.