Video enhanced depth-sensing indentation technique for characterizing mechanical behaviour of biomaterials

A video enhanced depth-sensing indentation with concomitant experimental technique was developed for the purpose of characterizing the mechanical behaviour of biomaterials. This indentation system possesses the capability of simultaneously measuring the applied force and resultant displacement of biomaterials. Its motion unit is a dc motor incorporated with a PZT actuator, which are activated individually. It can generate a long travelling distance of up to 12.0 mm with a resolution of 0.1 mu m or discrete motion of up to 120.0 mu m with micro-steps less than 10 nm. An up-to-date force transducer is driven by the motion unit, which has a maximum range of 5.0 mN with a resolution better than 0.1 mu N. Armed with a high magnification side-view system, it can offer extra lateral profile variation of samples during the compression procedure, which is essential for observing and analysing the gradual rupture. The technique was applied to characterize the elastic properties of thin biomembranes and large deformation of a single biomimetic microcapsule along with its adhesion on a flat surface. Experimental results verified the performance and application of the homemade indentation apparatus. This study presented that the quantitative characterization of mechanical behaviour for broad varieties of biomaterials is feasible.