Smallest medical CMOS image sensor enables deeper endoscopy
Article By : Nitin Dahad
OmniVision has launched its smallest medical CMOS image sensor to enable deeper endoscopy procedures into the smallest parts of the anatomy.
OmniVision has launched its smallest medical CMOS image sensor and corresponding wafer-level camera module to enable deeper endoscopy procedures into the smallest parts of the anatomy.
Its new OH0TA OVMed medical image sensor shrinks the package size to 0.55mm x 0.55mm, features a 1.0 micron pixel and a 1/31” optical format, quadruples the RGB image resolution over its predecessor to 400×400, or 160 K Pixels, at 30 frames per second, while reducing the power consumption by 20% to 20mW.
This allows designers to add ultra-compact visualization to single-use and reusable endoscopes, as well as catheters and guidewires, with a small outer diameter of 1-2mm. Alternatively, this sensor’s uniquely small size gives medical device OEMs the flexibility to create a larger-diameter scope with a larger working channel.
Speaking to embedded.com, Tehzeeb Gunja, director of medical marketing at Omnivision, said, “Existing small endoscopes use fiber, and we’re using CMOS instead of fiber, which enables lower cost and higher resolution. We already had a small sensor, but customers were looking for that 400×400 resolution in a smaller size and lower cost.” He added, “CMOS at the tip of the endoscope is becoming more of a paradigm.”
The company said that medical procedures on the body’s smallest anatomy were previously performed either blind or with low quality images from fiberscopes, as existing cameras were too big and reusable endoscopes were not cost effective.
The OH0TA’s increased resolution allows higher quality color images to be captured from within the body’s smallest organs, enabling medical devices to reach deeper into the body for procedures such as neuro, ophthalmic, ENT, cardiac, spinal, urology, gynecology and arthroscopy, as well as dental and veterinary diagnosis and surgery. Additionally, the sensor’s lower power consumption reduces “chip on tip” camera heat for greater patient comfort and longer procedure durations, while also reducing noise for crisper images.
To achieve this increase in resolution, along with a smaller pixel size and optical format, the OH0TA is built on OmniVision’s PureCel Plus-S stacked die technology. This next-generation pixel technology also provides higher color fidelity and excellent low light sensitivity of 3600 mV/lux-sec, along with a high signal-to-noise ratio of 37.5dB for crisper images. Additionally, PureCel Plus-S enables the OH0TA’s higher full well capacity (FWC), zero blooming and lower power consumption.
Other key features include a 15.5 degree chief ray angle, enabling the use of lenses with high fields of view and short focus distances. It also supports a 4-wire interface, as well as raw analog data output, both of which can transmit via cables as long as 4 meters with minimal signal noise. For backward compatibility and easy adoption, this sensor interfaces with OmniVision’s existing OV426 analog-to-digital-conversion bridge chip. Additionally, it is autoclavable for reusable endoscope sterilization.
“The trend toward minimally invasive procedures continues to grow, due to their greater success rates and shorter patient recovery times. However, for the narrowest areas of the anatomy, particularly in neuro and cardiac surgeries, previous sensors did not have the necessary combination of high resolution and extremely small size,” said Ehsan Ayar, medical product marketing manager at OmniVision. “The OH0TA is the world’s first sensor to offer this combination, enabling significant endoscope improvements, especially in comparison to traditional videoscopes made with optical fibers, which have limited resolution, poor imager quality and high cost.”
Wafer-level camera modules for single-use endoscopy
Along with the new image sensors, OmniVision also announced its OVMed OCHTA camera module featuring its CameraCubeChip wafer-level technology, enabling it to match the small size of its predecessor, at 0.65mm x 0.65mm, for deep anatomical access. This technology allows for the integration of OmniVision’s new higher-resolution OH0TA image sensor, along with signal processing and wafer-level optics in a single compact package.
With OCHTA camera modules, endoscope, catheter and guidewire OEMs can now develop mass-produced, single-use devices with 1-2mm optical diameters and higher resolution to address the many challenges posed by reusable equipment, including cross-contamination risks and high maintenance costs.
OmniVision said it remains the only company to offer ultra-small chip on tip camera modules with backside illumination (BSI), which provides excellent image quality and better low-light performance to help reduce LED heat and improve sensitivity. BSI also allows the use of superior lens technology over competing front-side illumination cameras in this class, while improving patient comfort and accelerating recovery time. Additionally, with OmniVision’s economical CameraCubeChip wafer-level packaging technology, the OCHTA makes possible the mass production of high-resolution, single-use medical imaging equipment.
By integrating the image sensor, signal processor and wafer-level optics in a single compact package, the OCHTA also reduces the complexity of dealing with multiple vendors while increasing supply reliability and speeding development time. Furthermore, unlike traditional cameras, all CameraCubeChip modules are reflowable. This means they can be mounted to a printed circuit board simultaneously with other components using automated surface-mount assembly equipment, which increases quality while reducing assembly costs.
The analyst’s view
Market research firm Yole Développement (Yole) said that advanced node technology in CMOS image sensors (CIS) is bringing higher resolution, and innovative stack processes help to optimize the performance as well as the module size. Chenmeijing Liang, technology and market analyst for imaging at Yole, said, “These state-of-the-art CIS technologies are meeting today’s key endoscopy requirements to support doctors in their diagnostic processes or surgical procedures with higher image quality and better contrast, while increasing patient comfort. They also allow less invasive imaging techniques for neurologic, ENT or pediatric applications without altering image resolution.” With regard to single-use medical endoscopes, Yole sees strong demand for CMOS image sensor camera modules, predicting a US$241 million market at the end of 2025. This is currently reinforced by the Covid-19 pandemic, with regulations from health authorities strongly changing the endoscopy industry landscape. The aim is to avoid cross contamination in high-risk imaging procedures that use tiny endoscopes, like bronchoscopies, ureteroscopies or pediatric imaging diagnostics. Key requirements from caregivers include strong miniaturization of cameras, image quality increases as well as high contrast at low power to avoid any heat disturbances during procedures.
This article was originally published on Embedded.
Nitin Dahad is a correspondent for EE Times, EE Times Europe and also Editor-in-Chief of embedded.com. With 35 years in the electronics industry, he’s had many different roles: from engineer to journalist, and from entrepreneur to startup mentor and government advisor. He was part of the startup team that launched 32-bit microprocessor company ARC International in the US in the late 1990s and took it public, and co-founder of The Chilli, which influenced much of the tech startup scene in the early 2000s. He’s also worked with many of the big names – including National Semiconductor, GEC Plessey Semiconductors, Dialog Semiconductor and Marconi Instruments.
