Bridge Neurotech launched with $13.5 million in funding to compete with Sam Altman-backed Merge Labs in the race to build a brain-computer interface that relies on ultrasound. The venture firm General Catalyst, which has backed Anduril, Anthropic, Airbnb, and Stripe, is among the investors. The company joins a growing field of startups working to translate brain signals into useful actions, including Elon Musk's Neuralink, Synchron, Paradromics, and Precision Neuroscience.
Bridge founder and CEO Will Biederman said his decision to start the company came down to a difference in vision. Biederman developed the chip Neuralink licensed for its first devices during his PhD work, but he wants Bridge to build a wearable device that could reach far more people than a brain implant. He noted that only about 100 people worldwide have received an implanted brain-computer interface in clinical trials, including at least 21 volunteers who have gotten Neuralink's device. Biederman said the risks of neurosurgery cannot be minimized or dismissed and that nobody really wants a hole in their head.
Wearable brain-computer interfaces have struggled with poor signal quality, because bone and skin weaken electrical signals before they reach external sensors. That is why most companies record electrical impulses directly from neurons in the brain, and Neuralink and others have shown such systems can let paralyzed people control electronic devices, move robotic arms, and communicate in real time with their thoughts. Bridge Neurotech is betting that ultrasound, which uses high-frequency sound waves to bounce off moving red blood cells and measure the speed and direction of blood flow, offers an alternative. Fluctuations in blood flow in the brain closely follow neural activity.
Both Bridge Neurotech and Merge Labs have ties to Arbor Neuroscience, previously known as Forest Neurotech, a nonprofit founded in 2023 by Biederman, Sumner Norman, and Tyson Aflalo. The organization built an instrument that uses ultrasound to image brain function and is in trials in the UK. Merge Labs spun out of Forest Neurotech in January, with Norman and Aflalo among its cofounders, along with Altman, researcher Mikhail Shapiro, and tech entrepreneurs Alex Blania and Sandro Herbig.
Maryam Shanechi, a neuroengineer at the University of Southern California, said that because ultrasound measures brain activity indirectly from blood rather than directly from neurons, there is a natural delay of a few seconds between when neurons fire and the subsequent change in blood flow and volume. She said it captures a slower variation in neural activity that is fine for many applications but depends on what is being built. For real-time tasks such as moving a robotic limb instantly or rapid typing, that lag could pose a challenge for ultrasound-based interfaces. Bridge plans to use predictive AI models to reduce the lag and boost performance, and Biederman said the company is interested in both consumer and medical applications but did not comment on specific plans.
Bridge is starting its first clinical study in volunteers in Redwood City, California. The observational study, with no treatments or diagnoses involved, will place a small ultrasound probe on the side of the head of healthy adults and people who have undergone skull surgery. The probes, which use semiconductor silicon chips made by the portable ultrasound company Butterfly Network, will record brain activity while participants listen, watch, move, and speak.
Bridge is not releasing images of its device yet, but Biederman said it is something close to headphones that will sit on the temporal window slightly above the ear, the thinnest part of the skull and the easiest place to image through. Bone scatters and absorbs sound, presenting technical challenges for imaging noninvasively through the skull. A 2024 study by researchers from Caltech and the University of Southern California demonstrated that an ultrasound-based brain-computer interface could read and decode human brain activity, but it required removing a portion of the skull and replacing it with a window for ultrasound waves. Biederman said his vision is focused on noninvasive interfaces, where he believes the biggest opportunity to help people lies.
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