Bespoke pair of spectacles fitted with older analogue sensor, in case made by Silicon Valley Eye Physicians. Both spectacles and case are labelled “INT, Intermediate 2014”.

At first, Hawking controlled his voice software using a clicker. When he could no longer move his fingers, he and his team developed a custom-built system controlled by twitching his cheek muscles. A sensor mounted on his spectacles picked up these tiny movements.

In his later years, Hawking’s cheek movements had slowed his speech to 1–2 words per minute, and he was experimenting with systems to read his brain activity.