CELLS AND MEMBRANES - Nanoindentation with Biological Applications - page 326

Ball Ball

Deformed hydrogel membrane Deformed hydrogel membrane

Figure 10-4. A novel shaft-loaded (ball-bearing) blister test for characterizing creeping
deformation of a hydrogel membrane (adopted from Ahearne et al . 14 ).

only known long term creep test for an ultra-thin polymer membrane.
Creep was measured in natural and prosthetic cornea constructs for
6 weeks using this method.

2.5. Other methods

Fairly recently, a novel micro- or nanoindention technique based on
Optical Coherence Tomography (OCT) has been developed technique for
characterizing mechanical properties of biomaterials, particularly for
soft biomimetic membranes. 15 OCT is an interferometric imaging method
that utilizes the short coherence lengths of a broadband light source.
This method provides an on-line, non-destructive and real-time way to
characterize soft biomimetic or biological membranes. The equipment is
capable of in-situ monitoring of a creep test on soft hydrogel membranes.
A Micro-Electro-Mechanical-System (MEMS) has been developed
for the indentation of single biological cells. 16 The MEMS-based
capacitive sensor-actuator provides high accuracy in calibrating force
and displacement in 0.01 N and 1 m, respectively. More importantly,
the device can simultaneously aspire the cell as a function of pipette
actuation. The method has been applied to indent and pierce through the