Why “Passing EMC” Is Much Harder When the Product Touches the Body
The world of wearables and medical devices is growing rapidly—from fitness trackers and smartwatches to wireless ECG patches and digital hearing aids. But behind the innovation lies a less glamorous hurdle: compliance testing, particularly EMC.
Testing these compact, body-worn devices presents unique electromagnetic compatibility challenges that traditional EMC setups and assumptions don’t fully address.
At C-PRAV, we’ve worked with dozens of wearable and medical product developers, and here’s what we’ve seen:
1. RF Exposure & SAR: The Body Isn’t Just Nearby
– It’s Part of the System
For body-worn devices, RF exposure testing is mandatory in most regions (e.g. SAR testing in the EU, FCC, AU and many other regions).
Why it matters:
The human body absorbs RF energy—so you must measure the Specific Absorption Rate (SAR)
SAR testing setups simulate tissue response using phantoms, fluid, and robot arms. Devices that are worn closer than 20cm from the body often require more complex testing and lower power limits
💡 Tip: Plan early for SAR testing if your device uses Bluetooth, Wi-Fi, LTE, or other active radios.
2. Proximity Emissions & Immunity:
You’re Closer to Failure Than You Think
Because wearables are used very close to the human body, standard radiated emissions and immunity tests become more sensitive.
Challenges include:
Emissions from device antennas and clocks coupling into the body. External RF fields (e.g., from phones or Wi-Fi routers) disrupting small devices
IEC 61000-4-3 (radiated immunity) and 61000-4-6 (conducted immunity) are especially harsh on compact devices
📌 Many wearables fail radiated immunity tests due to poor shielding and internal grounding layouts.
🔋 3. Battery-Powered Devices: No AC Plug, Still Plenty of Noise
You might assume battery-powered wearables are “safe” from power-line emissions. But in reality:
- DC-DC converters generate high-frequency switching noise
- Charging circuits (USB, wireless) can introduce transient spikes
- Switching regulators are a common source of conducted emissions failures
💡 Use spread-spectrum switching, shielded inductors, and proper filtering to reduce EMI at the board level.
⚙️ 4. Test Setup Constraints: Small Form, Big Complications
Chambers and in general Labs are often built for larger devices. For wearables:
- Positioning is critical—even slight misalignment can affect SAR and emissions results
- Custom jigs are often needed to mimic real-world use (e.g., on-wrist, in-ear, under-shirt)
- Body simulants must match use cases (head, torso, wrist, etc.)
🔄 Testing may need to be repeated across multiple orientations and usage scenarios.
🧪 5. Regulatory Overlap: CE, RED, MDR, FCC, ISED, ARPANSA, and More
Medical wearables may fall under:
- CE (EMC, LVD, RED)
- MDR (EU Medical Device Regulation)
- FCC + ISED (North America)
- RCM + TGA (Australia)
- BIS + TEC + WPC (India)
Each has specific technical requirements. Don’t underestimate the need for harmonised test planning and multi-standard documentation.
✅ How C-PRAV Supports Wearable & Medical Device Compliance
We help & manage teams plan and test for:
- SAR and MPE (RF exposure)
- EMC (EN 55011, 55032, 60601-1-2, RED 3.1/3.2/3.3)
- Safety and charging compliance (including wireless, WPT)
- Technical file and Declaration of Conformity (DoC) preparation
- Test plan optimisation to reduce surprises in final certification
In wearable tech, your product is closer to the human body—and closer to EMC failure.
Plan for testing early, and treat compliance as a design input, not just an output.
