Bridge Neurotech bets an ultrasound wearable can open brain interfaces to people who won't have surgery

The thing a user would wear sits above the ear, roughly where headphones go. Bridge is not releasing pictures of the device yet, but Biederman calls it "something close to headphones" resting on the temporal window, the thinnest part of the skull. ^[4] Its probes use silicon chips from Butterfly Network, the portable ultrasound maker. ^[20]

Almost everyone else in this field cuts into the skull for the same reason: signal quality. Bone and skin weaken electrical signals before they reach a sensor on the outside, so most companies record impulses straight from neurons. ^[14] Neuralink, Synchron, Paradromics and Precision Neuroscience all take that surgical route. ^[8] Those implants have let paralyzed people control devices, move robotic arms, and communicate in real time by thought. ^[15]

Ultrasound skips the hole. It bounces high-frequency sound off moving red blood cells to measure blood flow, which in the brain tracks neural activity. ^[16] It reads the brain secondhand, though. Maryam Shanechi, a neuroengineer at the University of Southern California, says there is a natural delay of a few seconds between when neurons fire and the change in blood flow that follows. ^[1] "It captures a slower variation in neural activity," Shanechi said. "That's fine for a lot of applications, but it depends what you want to build." ^[2]

That delay lands hardest on the real-time tasks implants have already proven, like moving a robotic limb the instant you decide to or typing quickly, and Bridge says it will use predictive AI models to shrink the lag. ^[3] Biederman says the company is interested in both consumer and medical uses but would not describe specific plans. ^[18]

The pitch and the signal are two different things. The pitch is reach. Biederman developed the chip Neuralink licensed for its first devices during his PhD, then left to build a wearable he says could serve far more people than any implant. ^[10][11] "It fundamentally comes down to a difference in vision," he said. ^[12] "The risks of neurosurgery really cannot be minimized or dismissed, and so the level of safety and benefit that these devices must deliver really is quite high," Biederman added. "Nobody really wants a hole in their head." ^[13]

Bridge's closest rival is Merge Labs, the Sam Altman-backed startup chasing the same ultrasound approach. ^[7]

That makes the device a good fit for one kind of user and a poor one for another. Someone who wants brain input without surgery, and whose task can tolerate a second or two of delay, may find an ultrasound reader enough. ^[11] A person who needs to move a robotic arm the instant they decide to is still better served by an implant's direct signal. ^[15]