By Sean Fenske, Editor-in-Chief
 
Healthcare today is driven primarily by electronic medical devices. As such, these therapeutic tools need to work seamlessly in environments from a patient’s home to the ICU of the hospital. In order to make this happen, designers need to ensure they are connected properly. This doesn’t just mean wirelessly to the internet, but rather, to other devices, to the patient, to a monitor, or a host of other potential ways in which it can be physically connected.
 
While a physical connection may seem like a simple enough component for a medical device, there are an array of considerations developers need to keep in mind when selecting the connector. Is the device wearable? Does it live on an ambulance? Is it used in the OR, ER, or ICU? Could there be interference from other technologies? There are a multitude of other questions.
 
Fortunately, medical device designers don’t need to stay abreast of all these variables. Partnering with a knowledgeable connector provider can take all the guesswork out of any project. With this in mind, Richard Johannes, director of engineering and product innovation at LEMO USA, took time to identify some of the issues designers would need to think about.
 
Sean Fenske: With the continued growth of electronic medical devices, how have connectors been affected?
 
Richard Johannes: Connectors have been impacted by the continued growth of electronic medical devices through the drive toward flexibility. The increase of integrated active components has forced the addition of PCBs or hardwired devices. The number of sensors or low-energy signals have required the deployment of high density, high pin-count connectors, which are terminated to small conductor coaxial cabling or flexible printed circuit board technology.
 
Fenske: Does the incorporation of “smart” technology further impact the connectors used for medical devices?
 
Johannes: The incorporation of “smart” technology increases the connector’s sensitivity to static discharge, as well as the control of signal integrity and impedance. In addition, the inclusion of the devices in high density packages can create issues with sealing (particularly with autoclave sterilization) and electrical grounding.

 
Fenske: What factors are important with a connector for a handheld device that may be used wirelessly as well?
 
Johannes: The biggest factors impacting connector design for handheld devices include a compact high-density footprint, shielded conductors to minimize crosstalk, and the control of signal integrity dependent on signal speed and edge rate.
 
Fenske: One demand from OEMs that doesn’t seem to be slowing is the need to make devices smaller, which means the components, such as a connector, need to be smaller. How has miniaturization impacted the connector used for medical devices?
 
Johannes: The drive to smaller and higher density connectors is causing the need for innovation in providing termination of ultra-small conductors, sufficient spacing for creepage and clearance of higher voltages, and careful selection of materials to achieve robustness in the face of typical application forces and environmental rigors, such as autoclave or ethylene oxide sterilization.
 
Fenske: What about where the device is intended to be used? Does connector selection vary if a device is used in a non-medical environment, such as the home? What about devices that may need to be taken with a patient during a trip?
 
Johannes: Application is a major factor in connector design and selection. Wearable connectors must be intuitive in use and robust to withstand abuse in uncontrolled environments. Other factors must be considered including flammability, sunlight exposure, mechanical shock, biocompatibility, and durability, just to name a few.
 
Fenske: What about connectors that must address the flow of data? If the device collects information from a patient, how might this impact the selection of the connector?
 
Johannes: The selection of connectors for data applications is highly dependent on the nature of the data and speed/rate of data collection. If the data is low-energy sensor data, it is easily corrupted by EMI/crosstalk and must be shielded. It is also subject to attenuation if the resistance of the conductors is too great. If the data is transmitted at higher data rates, impedance must be controlled through the transmission line from end-to-end unless it is fiber-optic based in which case interface protection is critical. Finally, in all cases, the data must be protected against outside eavesdropping to prevent privacy violations.
 
Fenske: Do you have any additional comments you’d like to share based on any of the topics we discussed or something you’d like to tell medical device manufacturers?
 
Johannes: The design and selection of connectors and interconnect systems are very application specific. It is important that your interconnection partner is well versed in the details of the medical device in development. They need to be intimate with the materials, regulatory compliance, contact physics, environmental constraints, cost balance, and physical space and performance requirements that individual connectors must meet. It is also important to understand the pedigree of the interconnect system and recognize having one supply partner for both sides of the connection interface are essential to maintain a quality interconnect.
 
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