According to CoinMeta, Wu said that a developer has open-sourced entropy32 plus, which is a Bitcoin mnemonic phrase generation device that utilizes radioactive decay as a source of entropy. The device records the time intervals between decay events using a Geiger counter, and after processing through SHA-256, these intervals are mapped into BIP39 mnemonic phrases. The entire process runs offline, without any wireless connection, and no mnemonic phrases are stored permanently. The project has made the firmware, PCB, and the 3D casing design public. However, the author emphasizes that the entropy quality of the device has not yet been verified according to the NIST SP 800-90B standard. The project is mainly intended for amateur and educational purposes, and it is not recommended to use it for protecting large amounts of funds before independent auditing.