Today’s small, ultra-flexible robots require coaxial cable designed specifically for each application. Here are guidelines to keep in mind when selecting wires and robotics cable for medical applications.
Modern medical robots are increasing in complexity while decreasing in size. Such changes are calling
for custom cable and military cable that are smaller and more flexible while containing a greater number of conductors. The design of a cable revolves around its conductors. Size is usually stated in AWG, which stands for American Wire Gage, but it can be given in millimeters squared. However, before considering size, the materials now required for small medical robots must be examined. Although copper has been the material of choice for many years, it lacks the tensile strength for small, flexible wires. High-strength copper alloys are now the minimum required. And as size decreases, the use of stainless steel and titanium is increasing.
The plating on a conductor is used to improve corrosion resistance and enhance solderability.
Traditional tin plating is giving way to silver because most high-strength alloys cannot be coated with tin.
However, stainless steel and titanium, which have very poor conductivity, can be gold plated to restore
enough conductivity for small wires.
The size of the conductor is determined by the current or resistance values that the circuit requires.
Often the conductor has the highest resistance that the designer can allow in order to keep
the cable small. Tables are available in most handbooks for copper; these must be
corrected—by using the %IACS factor—when using alloys. This factor is a percentage of
the conductivity of the alloy compared to copper. Because it is expressed as a percentage
of copper, it must be used as the divisor to correct the ohm/foot for copper to that of the
alloy.