The wireless transmitter went in next. Tiny circuit board, barely bigger than his thumbnail. It would take the analog EEG signals, convert them to digital data, and broadcast at 2.4 GHz to the smartwatch.
Low latency was critical. He needed sub-100-millisecond response time for the BCI to feel natural. The transmitter was designed for that—high bandwidth, minimal processing delay.
Micro-battery installation. He'd chosen lithium polymer cells rated for 500 milliamp-hours each. The EEG sensors used maybe 5 milliamps. The transmitter used 15 milliamps. Total draw: 20 milliamps.
Battery life: 500 divided by 20 equals 25 hours of continuous use.
Not great. But he'd designed the system to sleep when idle. When he wasn't actively using the BCI, the sensors would power down. The transmitter would go into low-power mode.
Real-world battery life: probably two days with normal use.
