In Episode 23 of No Dumb Questions, we explain the design and function of low-noise cables, which are engineered specifically to minimize triboelectric noise.
Triboelectric noise is electrical interference generated when dissimilar materials rub against each other and transfer electrical charges—similar to static electricity created when rubbing a balloon against hair. Within a cable assembly, friction between different components (such as conductors, dielectric insulations, tapes, and fillers) can generate unwanted electrical charges whenever the cable is flexed, bent, twisted, or subjected to mechanical shock.
This unwanted noise degrades signal integrity in sensitive, high-precision applications, including:
- Medical imaging equipment: Ultrasound and endoscopic cameras where motion artifacts disrupt image clarity.
- Audio and musical instruments: High-gain guitar and stage equipment where movement introduces microphonic popping and hum.
- Precision sensor systems: Dynamic test fixtures, such as sensors on automotive crash-test dummies.
To mitigate triboelectric noise, engineers focus on two main strategies: selecting low-friction, charge-resistant materials (often incorporating conductive or semi-conductive layers) and utilizing specialized manufacturing techniques that lock internal components in place to prevent relative motion.
We also demonstrate how New England Wire tests for low noise using the ANSI/AAMI EC53 standard. A cable sample is suspended between two fixed posts with a central weight attached. Dropping the weight creates a mechanical shock, and the resulting triboelectric voltage spike is captured and quantified on an oscilloscope to verify cable performance.
Key Technical Takeaways
- Triboelectric Effect: Electrical charge generation and voltage spikes caused by friction between dissimilar materials during movement or impact.
- Internal Friction Points: Rubbing between conductors, dielectric insulations, wraps, and fillers creates microphonic noise that interferes with delicate signals.
- Critical Applications: Essential for medical monitoring/imaging, high-end audio cables, and precision impact sensors.
- Mitigation Techniques: Low-friction material selection, anti-static layers, and manufacturing processes that minimize internal movement.
- Standardized Testing: Evaluated using the ANSI/AAMI EC53 weight-drop shock test monitored via an oscilloscope.
But wait, there’s more! Stay tuned for Episode 24: What is resistance and how is it measured?
Episode 23 Transcript – What are Low Noise Cables?
Welcome to No Dumb Questions
Welcome to another episode of No Dumb Questions, where the only dumb question is the one that isn’t asked. From time to time, here at New England Wire, we get asked about low noise cables. What are low noise cables? Basically, these cables are designed so that triboelectric noise is minimized.
So let’s quickly talk about what triboelectric noise is, how we can mitigate it when it comes to cables, and how we test for it.
What is Triboelectric Noise?
So triboelectric noise is a result of dissimilar materials rubbing against each other. And then there is a transfer of electrical charges. So as an example, you may have rubbed a balloon against your hair and then stuck it to the wall. Why does this happen? Well, here you have an example of two different types of materials. You have your hair and the balloon, which is typically made of rubber. When you rub them together, you get a transfer of charges so that the balloon now becomes negatively charged and is attracted to the wall, which is positively charged.
This transfer of charges also happens in cables. Cables are made of different materials. You have conductors, you have insulations, you have tapes, you have fillers. So when cables are flexed or banged around, there’s always a possibility of triboelectric noise.
Why Minimizing Noise Matters: Medical, Audio, and Sensors
Why is this important—to negate triboelectric noise? Because oftentimes this has an effect on signal integrity.
You can just imagine a medical cable if you’re trying to view, for example, internal organs or maybe a baby moving. By flexing the cable and creating triboelectric noise, this can affect your video. Or for example, music, musical instruments. They’re typically connected from, let’s say, a guitar to a speaker via a cable and an amplifier. Well, by shaking the cable, it can affect the clarity of the music. Or sensor cables, for example for crash test dummies. You want the signals that hit those sensors as accurate as possible. This is why triboelectric noise—or minimizing it—is important for cables.
Mitigating Triboelectric Noise in Cable Design
So how do we mitigate or reduce triboelectric noise in cables? There are two basic ways. One is the selection of materials. We try to select materials where that transfer of electric charge doesn’t happen as easily. The second way is by manufacturing techniques. By making sure that the components within the cables don’t move, we can try to reduce the effects of triboelectric noise.
ANSI/AAMI EC53 Testing for Low Noise
So how do we test for low noise here at New England Wire? Well, we use standard ANSI/AAMI EC53, which has a test method in there that allows for testing for triboelectric noise. Basically, we take a section of cable that is suspended by two posts. In the middle of that, you have a weight. One end is connected to an oscilloscope, so you drop the weight that creates the shock, which creates some noise, which is recorded on the oscilloscope. And that’s basically what we get for results for triboelectric noise.
So we’ve talked about what triboelectric noise is, how to reduce its effects in the cable, and how to test it. Hopefully this information has been helpful. Please continue to send us any additional questions, and here at New England Wire, we’d be happy to help you.