Oura just released its fifth-generation smart ring. The device measures 40% smaller than its predecessor. At 6.09 mm wide and 2.28 mm thick it sits closer to a traditional wedding band than any prior model from the company. MacRumors reported the dimensions drop from 7.99 mm wide and 2.88 mm thick on the Ring 4. The change addresses years of user feedback about bulk. But size tells only part of the story. Engineers rebuilt mechanical, electrical, optical, battery and sensing systems from scratch. Low-profile sensor domes press closer to skin. Twelve signal pathways now feed data. LEDs pump out stronger pulses. The result delivers greater accuracy across finger types and skin tones. Pulse signals reach up to 100 times stronger than those from wrist devices.…