Synchron
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Synchron is a clinical-stage neurotechnology company developing the Stentrode, a minimally invasive, endovascular brain-computer interface (BCI) intended to restore digital communication and device control for people with severe motor paralysis.[^1][^2] Founded in 2012 as a spinout of the University of Melbourne by neurologist Thomas Oxley, biomedical engineer Nicholas Opie, and interventional cardiologist Rahul Sharma, the company is dual-headquartered in New York City (Brooklyn) and Melbourne, Australia.[^3][^4] Unlike intracortical systems from [[neuralink|Neuralink]], Paradromics, or Blackrock Neurotech, the Stentrode is delivered through the jugular vein and placed inside the superior sagittal sinus, a large dural venous channel adjacent to the primary motor cortex, eliminating the need for a craniotomy.[^5][^6] In July 2021, Synchron became the first company to receive an Investigational Device Exemption (IDE) from the U.S. Food and Drug Administration for a permanently implanted BCI, and in July 2022 it implanted its first U.S. patient at Mount Sinai West in New York.[^7][^8] As of late 2025 the company had implanted ten patients across the Australian SWITCH and U.S. COMMAND early feasibility studies, completed a $200 million Series D, and announced native integration with Apple's iPhone, iPad, and [[apple_vision_pro|Apple Vision Pro]] platforms.[^9][^10]
| Field | Value |
|---|---|
| Type | Privately held neurotechnology company |
| Founded | 2012 (Melbourne, Australia) |
| Founders | Thomas Oxley, Nicholas Opie, Rahul Sharma |
| Headquarters | Brooklyn, New York; Melbourne, Australia |
| CEO | Thomas Oxley |
| Flagship product | Stentrode (endovascular BCI) |
| First human implant | August 2019 (SWITCH, Melbourne) |
| First U.S. implant | July 6, 2022 (Mount Sinai, New York) |
| Total funding (Nov 2025) | ~$345 million across Seed to Series D |
| Lead investors | ARCH Venture Partners, Khosla Ventures, Double Point Ventures, Gates Frontier, Bezos Expeditions |
| Regulatory status | FDA Breakthrough Device Designation (2020); IDE (2021); pivotal trial in planning |
The concept that became the Stentrode originated in 2007, when neurology resident Thomas Oxley, then training at the Royal Melbourne Hospital, began searching for a way to access the cortex without opening the skull. Inspired by routine endovascular procedures used by interventional radiologists and cardiologists to treat strokes and aneurysms, Oxley reasoned that the dense venous channels lying immediately beneath the cortical surface could provide a natural delivery route for a recording array.[^4][^11] In 2010, Oxley cold-called Colonel Geoffrey Ling, then director of the Defense Sciences Office at the U.S. Defense Advanced Research Projects Agency (DARPA), and pitched the idea; DARPA funding followed and supported the early sheep studies at Melbourne.[^11][^12]
The translational engineering work was led by Nicholas Opie, who hand-built early Stentrode prototypes at the University of Melbourne's Vascular Bionics Laboratory. Rahul Sharma, then training as an interventional cardiologist at Stanford, provided clinical expertise on catheter-based vascular delivery.[^4][^13] In 2012, the three co-founders incorporated Synchron Australia Pty Ltd to pursue the technology commercially while maintaining academic affiliations with Melbourne and Mount Sinai.[^3][^4]
Between 2012 and 2018, the Synchron team published a series of preclinical studies in sheep demonstrating that a self-expanding stent embedded with platinum electrodes could be delivered transvenously to the superior sagittal sinus, achieve long-term endothelial integration with the vessel wall, and record chronic electrocorticographic (ECoG) signals.[^5][^14] A key 2016 paper in Nature Biotechnology established that the Stentrode could resolve cortical local field potentials with bandwidth comparable to epidural ECoG arrays, while preserving venous patency over several months.[^14]
In November 2018 the St Vincent's Hospital Melbourne Human Research Ethics Committee approved a first-in-human study, and in August 2019 surgeons at the Royal Melbourne Hospital implanted Graeme Felstead, the first patient with motor neuron disease to receive a Stentrode.[^5][^15]
In August 2020 the FDA granted the Stentrode Breakthrough Device Designation, an expedited-review pathway for technologies that may offer more effective treatment for serious or irreversibly debilitating conditions.[^5][^16] On July 28, 2021, the agency awarded Synchron an Investigational Device Exemption (IDE) to begin the COMMAND early feasibility study, the first IDE the FDA had ever granted for a permanently implanted BCI.[^1][^7]
Synchron implanted its first U.S. patient on July 6, 2022, when neurointerventional surgeons at Mount Sinai West in New York City delivered a Stentrode into the cerebral venous sinus of an ALS patient.[^8][^17] The implantation was the first in the COMMAND trial, an early feasibility study run jointly with Mount Sinai Health System, the University at Buffalo Neurosurgery and Gates Vascular Institute, and the University of Pittsburgh Medical Center in collaboration with Carnegie Mellon University.[^18][^19]
In January 2023 the JAMA Neurology paper reporting the Australian SWITCH study results was published, becoming the first peer-reviewed report of long-term safety of an endovascular BCI in humans.[^20][^21] In August 2023 Synchron completed enrollment of six patients in the U.S. COMMAND study, and in September 2024 it announced that all six had met the primary safety endpoint over a 12-month evaluation period.[^18][^22]
Throughout 2024 and 2025 Synchron expanded the consumer and AI ecosystem around the Stentrode: in July 2024 it announced an OpenAI-powered chat feature, in July 2024 it demonstrated the world's first use of [[apple_vision_pro|Apple Vision Pro]] by a BCI patient, in January 2025 it announced a partnership with [[nvidia|Nvidia]] built on the Holoscan edge-computing platform, in March 2025 it unveiled Chiral, a cognitive AI brain foundation model, and in May 2025 it announced that the Stentrode would be the first BCI to natively integrate with Apple's new BCI Human Interface Device (BCI HID) protocol on iOS, iPadOS, and visionOS.[^23][^24][^25][^26][^27]
In November 2025 Synchron closed a $200 million Series D led by Double Point Ventures, bringing total disclosed funding to roughly $345 million and supporting preparations for a pivotal clinical trial and commercial launch.[^9][^10]
The Stentrode is a self-expanding nitinol (nickel-titanium) stent measuring approximately 4 to 8 millimeters in diameter when expanded and approximately 4 to 8 centimeters in length, sized to match the lumen of the human superior sagittal sinus.[^28][^6] Sixteen thin-film platinum electrodes with a surface area of about 0.3 square millimeters and 3 millimeter inter-electrode spacing are mounted on the stent struts in a circumferential array, oriented so that when the stent self-expands the electrodes press against the dural wall of the sinus immediately above the motor cortex.[^21][^29]
A transvascular lead exits the cerebral venous system via the internal jugular vein and tunnels subcutaneously down the neck and chest, terminating in an internal receiver-transmitter unit (the Synchron Switch) implanted in an infraclavicular subcutaneous pocket, analogous to the placement of a cardiac pacemaker generator.[^21][^28] The internal unit amplifies and digitizes the recorded neural activity and transmits it wirelessly to an external relay, which forwards the decoded signals over Bluetooth to a tablet, phone, computer, or headset.[^28][^30]
Implantation is performed by a neurointerventional radiologist or vascular surgeon under general anesthesia using techniques routinely employed for mechanical thrombectomy in stroke care. A guide catheter is introduced through the right internal jugular vein, advanced through the sigmoid and transverse sinuses, and into the posterior third of the superior sagittal sinus. A delivery catheter then deploys the self-expanding Stentrode in the target segment of the sinus, where it endothelializes into the vessel wall over the following weeks.[^28][^21] The total procedure typically requires a single-day admission rather than the multi-day inpatient stay associated with craniotomy-based BCI implantation, and recovery does not involve scalp wound healing or craniotomy site complications.[^11][^29]
The Stentrode records broadband electrophysiological signals through the venous wall, capturing local field potentials and ECoG-quality signals in the high-gamma band (roughly 65 to 200 Hertz) that correlate with attempted movement in the underlying motor cortex.[^14][^31] Independent peer-reviewed studies of two ALS patients implanted with the Stentrode reported motor-related modulations in the gamma and high-gamma bands sufficient to drive a digital switch, with bandwidth reported as comparable to epidural ECoG arrays.[^31][^32]
The 16-electrode design provides a lower channel count than penetrating arrays such as the Utah Array (96 channels) or the Neuralink N1 implant (more than 1,000 threaded micro-electrodes), but Synchron-affiliated researchers and independent reviewers have argued that the device's stability, lower surgical risk profile, and compatibility with existing neurointerventional workflows compensate for the reduced channel count in the targeted use case of switch-style digital control.[^6][^29][^32]
The clinical product built around the Stentrode is branded the Synchron Switch motor neuroprosthesis. The system decodes the patient's attempted-movement signals into discrete digital outputs (clicks, drags, and selections), which can be paired with eye-tracking or head-tracking for cursor positioning to deliver hands-free control of consumer operating systems.[^21][^33] In the JAMA Neurology SWITCH report, all four Australian study participants used the system to perform texting, emailing, online banking, and shopping; none of the patients experienced device-related serious adverse events, device migration, or sinus occlusion through 12 months of follow-up.[^21][^20]
The Stentrode With Thought-Controlled Digital Switch (SWITCH) study was an open-label, single-arm, first-in-human feasibility trial conducted at the Royal Melbourne Hospital between August 2019 and 2021. Five patients were enrolled and four were implanted and completed the primary 12-month follow-up; all four had severe upper-limb paralysis due to ALS (three patients) or primary lateral sclerosis (one patient).[^21] The primary safety endpoint, defined as no device-related serious adverse event resulting in death or permanently increased disability within 12 months of implant, was met in 100 percent of the cohort. There were no clots, no device migrations, and signal quality remained stable over the follow-up period.[^21][^20] The results were published in JAMA Neurology in January 2023 by Mitchell and colleagues.[^21]
The COMMAND early feasibility study (NCT05035823) was authorized by the FDA's IDE on July 28, 2021 and enrolled six U.S. patients with severe chronic bilateral upper-limb paralysis between May 2022 and August 2023.[^7][^18] The trial was run at three sites: Mount Sinai Health System in New York, the University at Buffalo Neurosurgery and Gates Vascular Institute in Buffalo, and the University of Pittsburgh Medical Center in collaboration with Carnegie Mellon University.[^18][^34] In September 2024 Synchron announced that all six patients had completed one year of follow-up with no device-related serious adverse events, no neurologic safety events, accurate deployment of the device in 100 percent of cases, and stable capture of motor-intent signals translated into digital outputs.[^22][^35]
In 2024 and 2025 Synchron expanded its program through a chronic-implant follow-up cohort and through the launch of a BCI patient registry to support comparative effectiveness analyses and to inform the design of a pivotal study.[^36] Company statements through 2024 and 2025 indicate that the pivotal trial, intended as the basis for a Pre-Market Approval (PMA) submission, is in active planning with enrollment expected to begin once the next-generation device is finalized; expected FDA review and approval has been discussed in the 2028 timeframe.[^37][^9]
In July 2024 Synchron announced the world's first use of [[apple_vision_pro|Apple Vision Pro]] by a BCI patient: Mark, a 64-year-old man with ALS implanted in the COMMAND trial, used the Stentrode to play Solitaire, watch Apple TV, and send text messages on the Vision Pro hands-free.[^25][^33] On May 13, 2025, Apple announced a new BCI Human Interface Device (BCI HID) protocol, formally recognizing neural interfaces as a native input modality, and Synchron announced simultaneously that the Stentrode would be the first BCI to integrate with the protocol, providing native control of iPhone, iPad, and Apple Vision Pro through Switch Control on iOS, iPadOS, and visionOS.[^27][^38]
In January 2025 Synchron announced a collaboration with [[nvidia|Nvidia]] under which the Stentrode signal-processing pipeline was ported to Nvidia's Holoscan edge-AI platform, enabling lower-latency on-device motor inference.[^24][^39] At Nvidia's GTC 2025 conference in March 2025, Synchron unveiled Chiral, described as a "cognitive AI brain [[foundation_model|foundation model]]" trained directly on deidentified neural recordings collected from BCI users using generative pre-training techniques.[^26][^39] Synchron has stated that the model will continuously improve as additional devices are deployed, abstracting cognitive primitives from neural data in a manner analogous to how a [[large_language_model|large language model]] is trained on text. At GTC 2025, Synchron also demonstrated [[nvidia_cosmos|NVIDIA Cosmos]] and [[nvidia_omniverse|NVIDIA Omniverse]] integration for generating photorealistic simulations of household environments used to train motor-intent decoders.[^26][^40]
A live demonstration at GTC 2025 featured Rodney Gorham, an ALS patient implanted with the Stentrode, controlling lighting, music, a fan, a robotic vacuum, and an automated pet feeder in a simulated home environment using only thought-driven commands routed through an Apple Vision Pro headset.[^26][^40]
In July 2024 Synchron announced a chat feature for the Stentrode powered by [[openai|OpenAI]] models, in which [[chatgpt|ChatGPT]] generates context-aware predicted replies and the patient selects among them with a single thought-driven click, dramatically reducing the keystroke cost of conversation for patients who cannot speak or type.[^23][^41] The integration was demonstrated with Mark, the same COMMAND patient who later used the Vision Pro.[^23]
Synchron's $145 million in cumulative funding through 2022 came across seed, Series A, Series B, and a $75 million Series C closed in December 2022 and led by ARCH Venture Partners, with new participation from Gates Frontier (the personal investment vehicle of [[bill_gates|Bill Gates]]) and Bezos Expeditions (the personal investment vehicle of Jeff Bezos), plus existing investors including Khosla Ventures, NeuroTechnology Investors, METIS, Forepont Capital Partners, ID8 Investments, Shanda Group, and the University of Melbourne.[^42][^43]
In November 2025 Synchron closed a $200 million Series D led by Double Point Ventures, bringing total disclosed funding to approximately $345 million; participants included existing investors ARCH Venture Partners, Khosla Ventures, Bezos Expeditions, NeuroTechnology Investors, and METIS, as well as new backers Australia's National Reconstruction Fund Corporation, T.Rx Capital, Qatar Investment Authority, K5 Global, Protocol Labs, and the Central Intelligence Agency-affiliated venture firm IQT.[^9][^10] The Australian National Reconstruction Fund contributed approximately AUD 54 million of the round.[^44]
The contemporary clinical-stage BCI landscape includes several companies pursuing distinct architectures and surgical philosophies. The table below summarizes core technical differences as reported by company materials and peer-reviewed literature; numbers reflect the most recent publicly disclosed configuration in each program.
| Company | Founder(s) | Architecture | Approximate channel count | Surgical access | First in-human |
|---|---|---|---|---|---|
| Synchron | Oxley, Opie, Sharma (2012) | Endovascular stent in superior sagittal sinus | 16 | Jugular vein, catheter-based | 2019 (Australia) |
| [[neuralink | Neuralink]] | [[elon_musk | Elon Musk]] et al. (2016) | Penetrating polymer threads in cortex | ~1,024 |
| Paradromics | Matt Angle (2015) | Penetrating microwire bundle (Connexus) | ~421 to 1,600 | Craniotomy | 2025 (United States) |
| Blackrock Neurotech | Florian Solzbacher et al. | Utah Array (silicon penetrating microelectrodes) | 96 per array | Craniotomy | Hundreds of research implants since 2004 |
| Precision Neuroscience | Benjamin Rapoport et al. (2021) | Subdural thin-film electrode array (Layer 7) | ~1,024 per film | Microslit craniotomy or limited cranial access | 2023 (United States) |
Sources for the table values: Synchron's 16-channel Stentrode is documented in the JAMA Neurology SWITCH report.[^21] Neuralink's N1 implant uses 64 threads with 16 electrodes each, totaling 1,024 channels, as described in Neuralink's 2019 white paper and 2024 PRIME clinical update.[^45] Paradromics' Connexus device uses up to 1,600 microwires according to its 2025 first-in-human announcement.[^46] The Blackrock Utah Array provides 96 channels per implanted array.[^47] Precision Neuroscience's Layer 7 cortical interface is reported at 1,024 electrodes per film.[^48]
The key trade-off Synchron has pursued is surgical accessibility against signal density. Endovascular delivery avoids the perioperative risks of craniotomy (intracranial hemorrhage, infection of the bone flap, postoperative seizure) and is performed by neurointerventional teams already trained for stroke thrombectomy, of which there are several thousand worldwide. The Stentrode's 16 channels capture lower-resolution signals than penetrating arrays, but in the SWITCH and COMMAND studies these signals proved sufficient for switch-style and cursor-style digital control.[^21][^22] Penetrating-array competitors, by contrast, target much higher channel counts in the hope of enabling continuous-decoded outputs such as speech synthesis and fine-grained robotic control, at the cost of a more invasive procedure and a smaller pool of qualified implanting surgeons.[^29]
Across the SWITCH and COMMAND cohorts, ten implanted patients have used the Stentrode for activities of daily living that include sending and receiving text messages, online banking, online shopping, email, web browsing, controlling smart-home devices, playing simple games, and using consumer operating systems including Windows, iOS, iPadOS, and visionOS.[^21][^22][^25] Reported task performance has included sustained text-entry accuracy in excess of 92 percent over several months of follow-up in two patients with ALS, with no significant degradation of signal quality over the recording period.[^31][^21]
A 2025 medRxiv preprint by Synchron researchers reported that the strongest predictor of usable motor signal strength was the degree of overlap between the deployed Stentrode and the primary motor cortex (M1), suggesting that improvements in pre-operative imaging-based targeting could increase the number of high-quality channels recorded per patient.[^32] A separate 2025 preprint reported signal-to-noise ratio stability and absence of channel dropout over multi-month chronic implants.[^49]
Synchron's principal contribution to the BCI field has been to demonstrate that a clinically meaningful neuroprosthesis can be delivered through the cerebral vasculature rather than through the skull. Three implications follow.
First, the surgical pool that can deliver the device is much larger than the pool of trained functional neurosurgeons; the procedure resembles routine endovascular stenting and stroke thrombectomy, which is performed at thousands of comprehensive stroke centers worldwide. This may accelerate deployment if the device receives PMA approval.[^29][^11]
Second, the perioperative risk profile of endovascular delivery is well characterized through decades of experience with related vascular devices, potentially shortening the regulatory path relative to penetrating-array devices that introduce novel surgical risk categories.[^11][^29]
Third, the explicit philosophical commitment to a lower-channel, switch-oriented decoding paradigm represents a different bet from the high-channel speech-and-motor-restoration ambitions of Neuralink and Paradromics. The Synchron bet is that a switch-style "thought click," composed with existing accessibility infrastructure such as eye-tracking and Apple's BCI HID protocol, is sufficient to deliver useful function to the majority of severely paralyzed users.[^27][^29]
The integration of the Stentrode with [[large_language_model|large language model]]-based predictive text (via [[openai|OpenAI]]), with mixed-reality consumer hardware (via [[apple_vision_pro|Apple Vision Pro]]), and with edge-AI inference (via [[nvidia|Nvidia]] Holoscan) illustrates a strategy of pairing modest neural channel counts with abundant downstream compute. Predictive language models in particular can amplify a small number of binary neural signals into high-bandwidth communication, reducing the per-bit demand on the implant.[^23][^39]
Independent reviewers have noted several limitations of the endovascular approach. The signal is read through the dural wall and through approximately 1 millimeter of venous-sinus tissue, which low-pass filters cortical activity and reduces the achievable spatial resolution relative to subdural ECoG or penetrating electrodes.[^29][^32] The device's 16 channels constrain the dimensionality of decoded outputs and currently preclude high-bandwidth applications such as continuous decoded speech, which competing penetrating arrays have demonstrated in research settings.[^29] Long-term endothelial overgrowth could in principle degrade signal quality, although the SWITCH and COMMAND data through 12 months have shown stable recordings.[^21][^22]
Patient eligibility for the device is also restricted by venous anatomy: variations in the size and patency of the superior sagittal sinus, prior dural sinus thrombosis, or anomalous venous drainage may preclude safe deployment in some candidates. The device also requires lifelong consideration of anticoagulation strategy, with the Synchron protocol involving a defined post-implant antiplatelet course.[^21][^28]
As of mid 2026 the device remains investigational; it is not commercially available, and patients outside of the active clinical trials cannot receive it.[^9][^22] Synchron's projected PMA submission timeline has been discussed in the 2028 timeframe by company leadership, although that estimate is not a formal regulatory commitment.[^37]
The Stentrode sits within a broader landscape of brain-computer interfaces that includes intracortical microelectrode arrays (Blackrock Utah Array, Neuralink N1, Paradromics Connexus), subdural cortical-surface arrays (Precision Neuroscience Layer 7), epidural arrays (Onward, NeuroPace), and noninvasive electroencephalographic systems. The endovascular route Synchron pioneered has subsequently attracted interest from several academic and corporate groups exploring alternative vascular access sites and ultraflexible vascular probes.[^29][^50] The downstream AI software stack, including [[chatgpt|ChatGPT]] predictive text, [[apple_vision_pro|Apple Vision Pro]] visual interfaces, and [[nvidia|Nvidia]] [[foundation_model|foundation model]] training pipelines, mirrors broader trends in pairing assistive hardware with cloud and edge AI services.