Contact Recording Devices

There are a variety of methods that might be used to sense the "contact" event. However, without more information it would be hard to say which one might be most suitable.

Least inexpensive method may be a "data logger," or a "data recorder" of one sort or another. Without more information, that's about as good a suggestion as I can make. Try Global Spec or Data Logger Store

Let's say I want to record or log the movement of an object in a limited area for example a runner on the stadium track. How can it be accomplished?

Given the limited description of what you would like to accomplish, would that be continuous monitoring of movement and all forces, times, etc. associated with it, or would it be monitoring of impact forces of a runner's foot on a track the entire time one or two feet are in contact with the surface, or sensing the passage of a runner, or none or any of the above?

The exact nature of what you want to do will have to be described exactly if you want someone to tell you exactly how to do it.

I was involved in a research project 20 years ago to monitor the forces at various points on one's foot, for example, but the subject ran on a treadmill. The same thing can be done with a runner carrying around a portable data-logger.

If real-time data is needed, a limited area of track can be instrumented with a variety of sensors to measure force, speed, time of event (time one's foot is in contact with surface), etc. There are also methods for giving the runner instant feedback, but of course, such carryings-on will increase with complexity.

Your sensor also depends on the forces involved. If they are resonably small you could sandwich conductive foam between two contacts the closer the cantacts are pushed to gether the less the resistance. You could also use an air diaphragm and an electronic pressure guage, or a strain guage. You need to check what kind of output your sensor has to determine what type of data logger you would need. Sounds like a fun little project.

If one of the surfaces is conductive, one could measure the resistance between the two surfaces. When the resistance drops, the data acquisition system could strat a timer until the resistance increase again.