Zero-insertion-force connectors leverage channel density and high-power to drive the performance of medical imaging and monitoring equipment.
By Murtaza Fidaali
In the medical industry, demands on electronic connectors are continuously growing, whether it is the number of circuits required, mating and actuation cycles, electromagnetic interference (EMI) and crosstalk characteristics, or safety requirements. Demands conversely require shrinking in terms of size and budget. Fortunately, advancements in zero-insertion-force (ZIF) connectors are helping manufacturers meet such demands.
For example, suppliers of hospital and medical equipment want to increase the number of channels to transmit electronic signals in their products because this allows doctors, nurses, mothers, and fathers to see brighter, more vivid, high-resolution ultrasound prenatal images (see Fig. 1). High-resolution imaging calls for higher power requirements, which then drives a demand for heat-dissipating materials. While the need for more signal channels for better resolution may be straightforward to design engineers, it is particularly challenging for component engineers to meet these channel demands without significantly increasing the footprint, especially considering the additional heat-dissipation requirements.
 FIGURE 1. Ultrasound equipment can deliver higher resolution images with attention to crosstalk and EMI issues. |
One of the world’s largest suppliers of hospital and medical equipment needed such a connector solution for its next-generation ultrasound system. The new system required more than 400 circuits in a smaller connector package that had to withstand a minimum of 10,000 mating cycles while maintaining superior EMI and crosstalk characteristics. Additionally, the connector system had to meet stringent International Electrotechnical Commission (IEC) safety requirements, such as strict shutter regulations requiring strength and rigidity and low impedance standards.
Such constraints regularly affect medical equipment designers of imaging and patient-monitoring equipment when attempting to enhance portability and high-resolution features. Equipment must be portable to serve the expanded mobile medical needs of hospitals, as well as small towns and lesser-developed countries where equipment is more likely to go to the patient than in more urban areas. These portability and high-power trends lead to new demands on connectors.
However, as was the case with the above ultrasound example, increasing the channel options usually means lost real estate on a printed circuit board (PCB). To combat this hurdle, recent advances have allowed some connectors to offer nearly double the channel density with only a 20% increase in size.
The increase in contact density requires knowledge of EMI-proof assemblies, lower contact resistance, and reduced crosstalk factors. Customers also want these control systems in smaller packages with increased functionality. Such density and package-size advancements have been attempted in various ways, but landed contact solutions have proven particularly effective.
 FIGURE 2. Imaging applications, such as MRI and ultrasound equipment, require increased signal bandwidth to handle communications access to remote healthcare professionals. |
High-speed data-management trends are further complicating designs in medical electronics. Now that medicine has entered the digital age, sending diagnostic images and data not only across town, but across the world, is much more common. Additionally, as medical imaging is becoming more complex in terms of X-rays, magnetic resonance imaging (MRI), and computerized tomography (CT) scans, more bandwidth is required, particularly as resolution demands increase (see Fig. 2). The increased bandwidth and more electronic three-dimensional displays allow doctors to communicate with each other, regardless of location. Customers are also requiring new systems for recording patient data on solid-state-memory-like smart cards and memory cards, extending requirements to data-management systems. If healthcare professionals are able to access data at a patient’s bedside, patients are able to receive care at a more efficient rate.
ZIF connectors
Zero-insertion-force connectors have uses in a number of applications, including commercial and industrial manufacturing, entertainment, telecommunication, test and instrumentation, and transportation. Because the ZIF design provides single-handed mating and extraction operation, however, it is especially relevant to the medical industry because of its portability and durability.
In the ultrasound example above, no existing connector was capable of meeting all the channel density, durability, control systems, and safety requirements. Advances in standard ZIF connectors, such as the new D series, latching, portable (DLP) connector, meet the necessary functionality requirements of this and similar applications (see Fig. 3).
 FIGURE 3. The DLP connector is an advancement in ZIF connectors that addresses limitations of channel density, durability, control systems, and safety requirements. |
ZIF connectors are capable of a high pin count with a variety of contacts, including crimp, square PCB post, square wrap post, and buss. As with the DLP connector, ZIF connectors can use a landed contact system to cover more channels in a smaller footprint. The DLP connector offers 408 channels versus previous generation models that allow only 260 in comparable package sizes. The cam and bearing mechanism of the connector enables all of the contacts to mate at once with only a quarter turn of the shaft.
The newer ZIF connectors solve other issues too. Products must withstand the many mating cycles of mobile medical-imaging and patient-monitoring equipment. As was the case above, the DLP series ZIF connector features a minimum rated life of 10,000 complete mating and unmating cycles with no performance loss.
Additionally, certain micro-connectors in particular have a custom breakaway feature that virtually eliminates disconnect time, saving precious seconds, especially in medical applications. For example, when monitors go off, doctors may need to transport the patient immediately to another room, such as the operating room. If transporting the patient is necessary, doctors do not have time to worry about unplugging machines or breaking them to disconnect the patient from a monitor abruptly. The breakaway feature eliminates such concerns.
Robotic surgery
Surgical robots are another newly developing segment of the medical market, demanding connectors that reliably transfer the high-fidelity digital signals while resisting wear and tear caused by the constant assembling and disassembling of the systems. The ZIF connectors have protection against electromagnetic and radio-frequency interference, ensuring the flow of information needed to perform robotic surgery. The DL ZIF connectors not only provide protection, but they also connect the modular parts of the system, including the input unit, video monitors, robot arms, and end-factors. Other computer-enhanced surgical systems that use ZIF connectors, such as a hip-drilling machine developed by a major medical-equipment manufacturer that uses the DL connector, are reducing hospital costs by as much as 30%.
Such new connectors also meet the increasing expectations of crosstalk characteristics. If lines are too close together, signals can interfere with each other. As a result, signal lines must be placed a significant distance apart in order to improve signal integrity. However, the size concerns to achieve this are obvious. The contacts in the DLP connector mate directly with the plug-side PCB, which shortens the signal path, minimizes signal crosstalk, and allows groundbreaking density possibilities.
High-channel-density characteristics also make these connectors more cost efficient than many other solutions. Because of the increased number of contacts, they can cost as much as 25% less than singular, high-density rack-and-panel connectors on a per-mated-line basis. The DLP connector is compliant with the Restriction of Hazardous Substances (RoHS) initiatives, ensuring that medical-device manufacturers will not have to worry about “green” issues concerning their connectors.
The latest ZIF connectors are an effective solution to the portability and high-power demands of the medical industry. However, as new trends emerge, such as lead-free compliance, new materials and designs will pose new hurdles in the construction of connectors.
MURTAZA FIDAALI is business development director for Medical and Instrumentation, ITT Electronic Components, 666 East Dyer Road, Santa Ana, CA 92705. Tel: (714) 628-8282; Email: murtaza.fidaali@itt.com.
