Why Electrostatic Discharge is Your Worst Enemy

Growing up in the southern United States, I often found myself walking home in the midst of a torrential downpour. And if being soaking wet wasn’t enough, to add to the despair in my shivering body, this rain was accompanied by a copious amount of bone-rattling thunder and sky-illuminating thunder. To be honest, I really love the sights and sounds of lightning and thunder. But ever since those experiences as a kid, I’ve always been nervous near power lines during a storm having witnessed—from a distance mind you—the electrifying scene of the colliding charges of the lightning and power lines. The remnants of those two separate electrical currents, naturally, renders all component of the power lines severely damaged.

Electrostatic Discharge (ESD)—in short—is the sudden flow of electricity between two electrically charged objects caused by contact, an electrical short, or dielectric breakdown. Similar to a bolt of lightning striking and frying a power line, ESDs can cause permanent—yet sometimes unseen—damages within the interconnect structures. For this discussion, a medical device can be one “electrically charged object,” and the patient can be the other “electrically charged object.”

Where in the device is ESD protection incorporated?

For simplicity, we are going to break a medical device into two components; 1. The Capital Equipment, 2. The Disposable Device.

1. The Capital Equipment: This piece of the medical device typically has more room and ability to incorporate ESD protection. Also, more people are going to be interacting with the capital equipment, as opposed to the disposable portion of the medical device.
2. The Disposable Equipment: This is where ATL’s expertise in interconnect solutions and experience comes into play.

We suggest an extensive investigation into incorporating ESD protection into your capital equipment. For this discussion let’s break the disposable into three components: the Interconnect Solution (or Connector), the Wire; the Device:

• The Connector – The connector is typically either metal or plastic, metal connectors can intercept ESD arcs, but are too expensive for more disposable medical devices. A correctly designed plastic connector can meet pricing constraints and provide the required ESD protection. There are many ways to incorporate ESD protection into a plastic connector. A connector can be designed and produced to incorporate: Mylar, metal mesh, conductive filled materials, as well as a number of other possible materials to support and benefit your product, based on the products specific requirements.
• The Wire – The wire is the easiest component of the disposable to incorporate ESD shielding, with the use of wire shielding.
• The Device – The device will share many similarities to the connector. The design of the device should be discussed with experts in electronics, such as ATL Technology.

Is ESD testing required in a Medical Device Connector?

From the FDA’s Design Considerations for Devices Intended for Home Use Guidance for Industry and

Food and Drug Administration Staff; “Although not a requirement, the Agency generally finds testing to the following immunity tests levels acceptable for the home environment based on FDA’s experience with home use devices: Electrostatic Discharge (ESD): ± 8 kV contact discharge, ± 15 kV air discharge;”

From the FDA’s document on Electromagnetic Compatibility (EMC); “The different forms of EM energy that can cause EMI are conducted, radiated, and electrostatic discharge (ESD). EMI problems with medical devices can be very complex, not only from the technical standpoint but also from the view of public health issues and solutions.”

The FDA’s document Guidance for Industry and FDA Staff – Class II Special Controls Guidance Document: Computerized Labor Monitoring Systems states, “Immunity – FDA recommends EMC testing also demonstrate the device will perform as expected in the presence of other electrical and electronic devices or other sources of electromagnetic disturbance in the intended environment of use (immunity). The device should operate in an acceptable manner during and after exposure to various forms of electromagnetic disturbance. FDA recommends testing include exposure to electrostatic discharge (ESD) … [and other possible electrical disturbances and discharges]”

There are a myriad of other products and suggestions from the FDA that we could reference, but we try and keep our blogs short. From what the above represents, we would suggest you confirm with the FDA or an independent auditor the ESD requirements for your project, know what ESD testing the FDA will require for your specific product and, most of all, make sure that your product provides the safest possible outcome to the patient.