I have been reading on these forums about having a pressure sensor on the grips of an end effector, or on the contact point on a walker’s foot, to determine when an object is in contact.
I have done some research and found Quantum Tunnelling Compound. These can be purchased in pill form which only measure 3.6mm by 3.6mm by 1 mm, which would make them ideal for the purpose above.
Taken from Maplin website (large electronic retailer in UK).
“Making simple force sensors, speed controllers, proportional switches, amongst many other possible uses, couldn’t be any made simpler than when using QTC pills. QTC Pills change from an insulator of greater than 10M‡; to a conductor of less than 1‡; as a direct result of the force applied QTC Pills can be used in low power applications where a change in resistance is required to control the function of an electrical system. The speed of small DC motors in, for example, model cars, fans etc. can be directly controlled via simple mechanical interfaces without the use of electronics. In high power applications a QTC Pill can be used as a transducer to provide an input signal to control power electronics. The Pills are formed from extruded QTC, 3.6mm square by 1mm thick and are consequentially small enough to be simply integrated between existing switch contacts to provide spark minimization, soft start, proportional control, etc. QTC pills can also be used to make force sensitive resistors of variable sensitivity, for home projects such as robotic enhancement or security. Although primarily sensors, they could in this format, potentially carry sufficient current for direct switching of low power equipment.”
I have ordered a set.
Links:
Maplin: maplin.co.uk/Module.aspx?ModuleNo=44202&criteria=quantum&doy=9m11
More info: dur.ac.uk/psm.group/qtc.html
Google search: google.co.uk/search?hl=en&q=Quantum+Tunnelling+Composite&btnG=Google+Search&meta=