The benefits to humanity by resolving these issues are profound and far-reaching, from rapid development of biomedical devices to nanoscale structures increasing the capability of circuitry beyond our current limits. Further, the field of mechanotransduction has only the crudest tools available to elucidate the behaviour of cells. The remaining discussion details how the issues have been resolved for these complex materials.
Complex materials
A mathematical model was developed and solved by ABC to determine the best possible guidance regarding how stiff the measuring element should be, or rules for how quickly or how deep the measurement should be performed. Further, if comparisons are to be made for a range of different length, time or stiffness scales, this is now possible. Previously the selection of stiff springs masked the time-dependent nature of the materials, giving them the appearance of a more elastic material. As an example of where this effect was detrimental, poor choices of material selection for hip replacements were made because of this, trial and error resolved these issues. Biomedical implants and devices need no longer suffer from a poor choice of material selection.
Nanoindentation is the application of a nanoscale deformation, typically much less than one micrometre, and measurement of the compressive load required. Previously, the biggest problem with nanoindentation is that the stiffness of the spring pushing the indenter into the material is comparable to the effective stiffness of the material; hence the mutual compliance of these two elements cannot be neglected. Until the work of ABC there was no way to include this in the determination of time-dependent material parameters. No-one wants a replacement hip that is uncomfortable, fails to perform, or yields prematurely, yet this is exactly what resulted from the previous approaches to material determination. To counter this, hip replacement went through a rapid evolution to find suitable materials; in the future this will be far simpler as the material parameters can now be determined.
Since the advent of nanolithography, the art of fabricating nanoscale structures for nanocircuitry, there has been an increasing interest in indenting soft materials to make such structures cheaply and effectively. Thanks to the efforts of ABC this cannot only be modelled but also controlled enabling structures and nanocircuitry which were previously difficult to create.
The mathematical model also describes the indentation using optical tweezers within a cell and determines useful information about the structure, function, dynamic properties and diseased state of a cell which were previously unachievable all thanks to the work of ABC. Further, by combining this information with the novel methodology of Rawson et al., which can be found here, a powerful and robust tool for investigating mechanotransduction is created.
Acknowledgement
This work was supported by the European Union under the FP7 programme (NANOBIOTOUCH Project: FP7-NMP-228844).