Measurement of intracellular strain on deformable substrates with texture correlation.

Mechanical stimuli are important factors that regulate cell proliferation, survival, metabolism and motility in a variety of cell types. The relationship between mechanical deformation of the extracellular matrix and intracellular deformation of cellular sub-regions and organelles has not been fully elucidated, but may provide new insight into the mechanisms involved in transducing mechanical stimuli to biological responses. In this study, a novel fluorescence microscopy and image analysis method was applied to examine the hypothesis that mechanical strains are fully transferred from a planar, deformable substrate to cytoplasmic and intranuclear regions within attached cells. Intracellular strains were measured in cells derived from the anulus fibrosus of the intervertebral disc when attached to an elastic silicone membrane that was subjected to tensile stretch. Measurements indicated cytoplasmic strains were similar to those of the underlying substrate, with a strain transfer ratio (STR) of 0.79. In contrast, nuclear strains were much smaller than those of the substrate, with an STR of 0.17. These findings are consistent with previous studies indicating nuclear stiffness is significantly greater than cytoplasmic stiffness, as measured using other methods. This study provides a novel method for the study of cellular mechanics, including a new technique for measuring intranuclear deformations, with evidence of differential magnitudes and patterns of strain transferred from the substrate to cell cytoplasm and nucleus

Living chips and chips for the living

\u3cp\u3eIn this paper we present a polymer-last approach for the fabrication of (partly) flexible and stretchable sensors assemblies. The Flex-to-Rigid (F2R) platform is based on this approach and especially designed for the fabrication of very small sensor systems which can be folded into, or around the tip of minimal invasive instruments such as laparoscopic instruments, catheters or guide-wires. As an example the fabrication and assembly of a combined pressure and flow sensor on the tip of a 360 μm diameter guide-wire is presented. The F2R platform uses standard silicon manufacturing equipment in a standard production environment and is therefore suitable for high volume production. Using the same polymerlast approach stretchable circuits have been fabricated. As an example a stretchable Micro-Electrode Array for electrophysiology is demonstrated. The paper ends with an outlook on an entire new field in micro fabrication where living cells are co-integrated with silicon bases micro-systems resulting in truly Living Chips.\u3c/p\u3