Instrumentation • Electronics
4 Healthcare devices and systems rely on the robust design and performance of their electronics. Serge Buechli reports.
4 Les appareils et systèmes médicaux reposent sur la conception solide et la performance de leurs composants électroniques. Serge Buechli établit un rapport.
4 Medizinische Geräte und Systeme sind vom robusten Design und der Leistung ihrer Elektronik abhängig. Serge Buechli berichtet.
Healthcare connectors for medical electronics
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Fig. 1. Ergonomic design is key.
hen designing new equipment, electrical and mechanical engineers need to make sure that the user interface is unquestionably reliable. Cable
connections, switches, LCD touch screens need to withstand repeated handling and wear. Particularly important are the connectors and cables that will need to withstand repetitive handling by patients or medical staff. In addition to these first requirements, systems used in medical environments sometimes need to be repeatedly sterilised. Sterilisation is quite harsh on plastic material and electrical devices; it either involves high temperature, for instance autoclave (121°C to 134°C in a pressure chamber for over 15 minutes) or chemical solutions. Chemical solutions such as Ethylene oxide (EtO), Sterrad or Steris Cidex enable killing microorganisms including spores, but sometimes require long cycle time, may leave toxic residuals and can be costly. Finally, medical device designing also goes through selecting materials that are ‘health friendly’, or that are for instance FDA approved.
The requirements for new interconnects are essentially high number of mating cycles (guaranteed extensive product life), high density and fail-safe connections. While the devices become more complex and smaller, the density of the interconnections increases, in other words the connectors have to perform better in less space. With higher density, the assembly of small connectors becomes more difficult when soldering the multiple small cables and wires. Soldering is recommended for small volumes, it
requires less equipment (just a soldering iron), but each wire assembly requires more time. It is ideal to use crimping tools when assembling large volumes and high density connectors. Another advantage to crimping: no heat is required to make the assembly in the assembly house or on the customer’s end. By crimping the wire, the equipment can be later used in a higher temperature environment. Crimping requires more tooling such as hand crimping tool and contact positioners that will help crimping the contact in an exact position. The crimp contact’s barrel (location where the wires are inserted) is annealed. During production, an electrical coil
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