Cells are connected to each other through intercellular junctions. The mechanical properties of these junctions, which facilitate communication between cells, dictate their migration, growth, and proliferation. Likewise, deficiencies or mutations leading to abnormalities in cell junction behavior can result in skin lesions, heart arrhythmias, and tumor metastasis. Therefore, quantification of the mechanical interaction between cells may lead us to a deeper understanding of cell behavior, structure, communication, and therapeutics.
As a part of our investigation of biomechanics through single cell studies, we are developing MEMS-based techniques to probe the mechanical behavior of individual cell-cell junctions. A primary challenge in this research lies in achieving the range of forces and displacements required to accurately interrogate individual cell-cell junctions. Depending on the type of adhesion, the strength of a single junction ranges from 20 to 300 pN. Likewise, displacements required to significantly stimulate a junction can range from tens of nanometers up to microns. Accordingly, accurate characterization of the mechanical response of an individual cell-cell junction requires resolutions in force and displacement transduction of picoNewtons and nanometers respectively.
MEMS lend themselves naturally to cellular and subcellular level mechanical testing. Due to their intermediate size, MEMS serve as an excellent interface between our naturally macroscale tools and micro- or nano-scale biological systems. The well-established MEMS literature details numerous sensors and actuators exhibiting excellent performance characteristics. The size and robustness of these devices creates the possibility of applying multiple independent sensors and actuators in cell-friendly environments. Furthermore, many of the MEMS-based sensing and actuation schemes scale favorably. For example, the time response, sensitivity, and power consumption of electrostatic displacement sensors improve as their dimensions shrink. Thus as devices are designed for finer scales, their performance improves. We apply these design principles to enable comprehensive characterization of cell-cell junction behavior not possible with conventional experimental techniques.