Petal Bluetooth and Battery Safety

1. Summary

Petal is a worn wellness device that communicates over Bluetooth Low Energy (BLE) using brief, periodic data bursts rather than a continuous connection. As a result, its radio is idle the overwhelming majority of the time, and its average radiated radio frequency (RF) power is far lower than that of common consumer wearables and wireless earbuds that people already wear on-body and in-ear for long stretches each day.

Comparisons with popular consumer wearables highlight Petal’s safety profile:

• Versus a 24/7 health tracker (Whoop 4.0): Petal emits roughly 1/10th to 1/50th — about 2% to 10% — of the average RF radiated by an always-on tracker.

• Versus streaming wireless earbuds (AirPods): Petal emits approximately 1/1,250th to 1/5,000th — roughly 0.02% to 0.08% — of the average RF of earbuds streaming high-fidelity audio.

The difference is driven primarily by transmission mode and duty cycle: Petal transmits in short bursts and sleeps more than 99.9% of the time, whereas always-on trackers and streaming earbuds keep their radios active far more of the time. Petal collects and transmits data periodically versus continuously which is the key reason the Bluetooth radio can be off a majority of the time.

In addition, Petal's 65 mAh battery holds under 5% of the energy stored in a single wireless-earbud case charge, which keeps thermal and electrical hazard — both of which scale with stored energy — negligible.

2. RF Fundamentals

Below, we explain three key concepts to help our customers use Petal with confidence:

Non-ionizing radiation. BLE operates in the 2.4 GHz band. This is non-ionizing radiation, meaning it does not carry enough energy per photon to break chemical bonds or damage DNA. Its interaction with tissue is fundamentally different from — and far weaker than — that of ionizing sources such as X-rays. In fact, BLE frequencies are 50,000 - 100,000 times lower than frequencies considered ionizing radiation.

Peak power versus average radiated power. Peak power is the instantaneous output level while the radio is actively transmitting. Average radiated power is the output averaged over time, including all the intervals when the radio is idle. For a device that transmits only occasionally, the average is dramatically lower than the peak. Average radiated power is the more meaningful figure for real-world exposure.

Duty cycle. Duty cycle is the fraction of time the radio is actually transmitting. It is the single most important driver of the difference between the devices compared in this paper. A device with a low duty cycle spends almost all of its time with the radio off, so even if its peak power is comparable to another device, its average radiated power can be orders of magnitude lower.

3. Petal's RF Profile

Petal's BLE radio operates at the baseline floor for Bluetooth range:

4. Conclusion

Across every safety axis — peak power, transmission mode, duty cycle, average radiated power, and stored battery energy — Petal sits at or below the low end of everyday consumer devices that people already wear on-body and in-ear for far longer stretches than Petal's 4–6 hour daytime wear window. Its burst-based BLE design keeps average RF emissions a small fraction of those from always-on trackers and streaming earbuds, and its micro-battery keeps energy-related hazards negligible. With respect to RF emissions and battery scale specifically, Petal presents a low-exposure, low-hazard profile.