As featured on OpenSea:

Description: This LED heart necklace is simply gorgeous. Wear it on the red carpet or to the after-party. Constructed of printed circuit board silkscreened with nano-led ink. No battery is required. Blinkee NFTs now use ether energy to illuminate! Won’t fall off or damage your clothing. Blinkee NFT pins use a bio-magnetic clasp and are tuned to the body of the wearer.

Or here is a real-world LED Flashing Red Heart Necklace.