This breakthrough for high-resolution disposable endoscopes comes from an unlikely source
Two trends are dictating the evolution of endoscopes: higher quality imaging and a transition to disposable architectures.
Valens Semiconductor was the first company to release to market an A-PHY-compliant chip, and is moving forward with various engagements on medical endoscopes. [Image courtesy of Valens]
Each of these introduce new challenges for system designers. The breakthrough might come from an unlikely source: The automotive industry.
Automotive OEMs have been attempting to integrate higher resolution sensors inside their vehicles to reach higher levels of autonomous driving. Cars have as many as 20 high-bandwidth sensors, each delivering gigabits of data to compute units elsewhere in the vehicle.
Just like in the medical industry, this data is safety critical, as excessive latency or errors in the video/data could result in death. In both of these industries, data is often uncompressed to ensure artificial intelligence algorithms are streamlined.
The similarities between the automotive and medical industries don’t stop there. In many use cases, steady-state white gaussian noise dominates the noise profile. Automotive and medical, on the other hand, both must contend with fast transient noise profiles. In automotive, this could be from large electrical transients surging within the car during startup, for example, while in medical this could occur during the operation of electrosurgical equipment.
Legacy connectivity solutions could sufficiently handle these interferences when carmakers integrated sub-gigabit sensors for relatively low-resolution cameras. But as sensor resolutions rise and the signal-to-noise ratio decreases, connectivity solutions have become a bottleneck for innovation.
The MIPI A-PHY standard
[Image courtesy of Valens Semiconductor]
As a result, carmakers called for the creation of a new standardized connectivity technology that could handle long-reach, high-speed sensors safely and reliably.
The MIPI Alliance, a collaborative global standardization organization, created the MIPI A-PHY standard. It can handle bandwidth up to 16 Gbps per link, with a clear roadmap to 32 Gbps, enough to support the highest resolution sensors on the market today and in the foreseeable future. A-PHY can extend interfaces up to 15 meters in automotive, and longer for nonautomotive configurations.
Most importantly, it was designed from the ground up to handle the fast, transient noise types commonly found in automotive, and in medical. A-PHY reaches a Packet Error Rate of 1E-19, orders of magnitude lower than competing legacy solutions.
Medical use of MIPI A-PHY
Fiber-based endoscopes are limited in the video quality they can support due to the mechanical constraints of fiber bundles, imposing low video resolutions and severe optical aberrations.
The transition to high-image-quality videoscopes has been hampered by limitations of video connectivity technologies as well as reliability issues. Many doctors have complained about dropped frames and latency during surgeries.
Links in videoscopes today are prone to dropping during the use of electrosurgical equipment. These scopes rely most often on direct connections from the sensor to the processing unit, which can only be possible with low-bandwidth (low camera resolution) connectivity. Another option utilized by endoscope manufacturers is a low pin-count proprietary imaging interface, but once again bandwidth is limited in this configuration.
The automotive-grade MIPI A-PHY standard does away with these issues, facilitating long-reach, high-bandwidth links that work free of errors. In addition, the standard’s ability to converge multiple interfaces — including power and general-purpose input/output (GPIO) — helps with miniaturization efforts.
The unprecedented EMI resilience of A-PHY allows for one other benefit that could be uniquely relevant for medical endoscopes: bending of the endoscope tip. Chips based on the A-PHY standard can operate over unshielded channels and over cables that are less than 1 mm in diameter, or 30AWG wires, which would allow for an extraordinary field of view for medical professionals.
A-PHY and the disposable endoscope trend
[Image courtesy of Valens Semiconductor]
A-PHY was originally designed to miniaturize the serializer, transferring the digital processing to the deserializer. This is perfect for the disposable endoscope architecture, with a miniature, low-power, low-cost serializer in the disposable section of the endoscope and the smart deserializer in the non-disposable section.
A final benefit provided by the A-PHY standard for disposable endoscopes is easier manufacturability. Splitting the endoscope into a variety of assembly elements could lead to significant manufacturing cost reductions. Instead of producing the endoscope as a whole, manufacturers could separately produce the optical head, insertion tube, handler/control-section, and the connection cord, with simple assembly at the end of the process. The A-PHY standard is robust enough to handle the many in-line connectors that this kind of manufacturing process would require.
[Image courtesy of Valens Semiconductor]
The MIPI A-PHY standard is available for the medical device industry, with a variety of silicon vendors offering A-PHY compliant serializer/deserializer (SerDes) solutions.
Valens Semiconductor was the first company to release to market an A-PHY-compliant chip, and we are moving forward with various engagements on medical endoscopes. Some are preparing for clinical trials, while others are readying to seek FDA approval.
From the feedback we’re receiving from our endoscope customer and partners, our automotive-grade A-PHY-compliant chips could be exactly what is needed to deliver high-resolution disposable endoscopes to the medical industry.
Eyran Lida [Photo courtesy of Valens Semiconductor]
Eyran Lida is the co-founder and CTO of Valens Semiconductor, overseeing the company’s technology strategy. With 33 years of experience in communication systems software and 85 U.S. patents, Lida is an international expert in wireline hardwired DSP modem design and one of the lead technical contributors to the MIPI A-PHY standard.
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