Force and displacement measurement systems

Here I present some of my activities in the development of displacement and force measurement systems used to study dynamic biomechanical properties of biological systems. My work started at McGill University in Montreal, Canada, in collaboration with Dilson Rassier, and continued with Sensorica.

Micro and nano technology have recently opened the possibility for probing biomechanical properties of cells and their microenvironments. Cells process mechanical cues that in turn drive their functions, growth, differentiation, development, spatial migration, collective organization, etc. Our understanding of the microscopic biomechanical aspects of cells and organs is already coming to fruition, generating new disease and diagnostic paradigms. It is important to design new methods and instruments able to support the growing interdisciplinary work in this field, not only for fundamental scientific research, but also for clinical studies and diagnosis.

Here I describe methods for probing dynamic biomechanical properties of sub-cellular systems, in particular muscle contraction at the myofibril level. At McGill University I am perfecting a device, at its core having a new design of atomic force microscope (AFM), conceived to assist researchers and clinicians with minimal technical knowledge about its governing principles. The system can easily interface with other measurement methods. It greatly improves throughput of experimentation, it is easily adaptable for a great variety of samples, and it allows greater freedom for sample preparation and manipulation, as well as for the control of environmental conditions. Within Sensorica open value network I am co-designing a new force sensor based on optical fiber technology, the Mosquito.

The two systems are fully integrated with a highly modular and easily extensible LabView software controlling the sensor, a valves system feeding micropipette inlets and their positioning motor, a piezoactuator, and a CCD camera, enabling script-based automated experiments.

Other single point, uni-axial in-plane sensors have been reported in the literature. Although they have helped to produce important scientific results, they are far from being efficient and productive tools. Their level of integration is low, they cannot be easily interfaced with other measurement techniques, their operation is very complex and highly dependent on local know-how. The Mosquito combines the best features of all other reported systems.

Tools to Study Muscle Contraction

The Mosquito Scientific Instrument System - Developed by Sensorica open value network. An open source scientific grade instrument used in physiological and medical studies to probe dynamic mechanical properties of biological systems, from organs to sub-cellular structures. An ultra sensitive optical fiber-based force/displacement sensor device.

Integration and automation software - Generic and modular automation software (LabView 8.5) that integrates imaging, motion, dosing, and data acquisition devices. This program also contains modules for data conditioning, data processing, and data analysis.

Communications and publications

• Optical detection system for probing cantilever deflections parallel to a sample surface A. Labuda, T. Brastaviceanu, I. Pavlov, W. Paul, and D. E. Rassier; Rev. Sci. Instrum. 82, 013701 (2011); doi:10.1063/1.3527913 (4 pages)

• Rates of force development in MgADP-activated myofibrils isolated from skeletal muscles, Ivan Pavlov. Tiberius Brastaviceanu, Dilson Rassier; presented at New Directions in Biology and Disease of Skeletal Muscle, Ottawa, May 5-8, 2010