In many implantable medical devices, implantable contacts made from biocompatible materials are replacing traditional methods. For example, ImplanTac socket contacts from Hypertronics are being used in pacemakers to replace set-screws that mechanically connect the lead to the pacemaker. According to Tom Kannally, Medical Industry Manager, Hypertronics, set-screws depend upon the amount of torque the surgeon puts on the screw. If there is not enough torque, electrical contact could be intermittent, or the system could disconnect entirely. The screw can also be damaged as the surgeon tightens it, which can destroy the device or harm the patient.
But not all implantable contacts designed to address these challenges actually do the job. Some implantable contacts can cause the same damage as the older methods they replace. Many implantable contacts are designed so that the wires are situated at right angles to the lead, says Kannally. If misalignment occurs when the lead is inserted, the contact and the implantable device can be damaged easily. The HyperTac contact uses spring wires that follow the same direction as the lead itself, so when the lead is mated, it mates in the direction of the wires. ‚â€œIf you were to misalign it slightly, you would be less likely to damage it. Also, if you were to damage one wire, it would not affect the others because they are independent of each other,‚â€ says Kannally. ImplanTac contacts have a hyperboloid-shaped basket of individual spring wires strung at an angle to the socket‚â€™s axis. When the pin is inserted into the sleeve, the wires stretch around it, creating a number of linear contact paths.
The contacts suit devices such as implantable cardioverter-defibrillators, neurostimulators, metabolic controls, circulation pumps, bone growth stimulators, and pain management devices.