Success Story

Active Pixel Sensors Lead Dental Imagery into the Digital Age

They’re in your cell phone camera and DSLR, but they were likely in your dentist’s X-ray machine first: CMOS digital image sensors.

NASA spent much of the 1980s developing imagers based on charge-coupled device (CCD) technology, which had enabled the first digital cameras. But in the early 1990s, Jet Propulsion Laboratory (JPL) engineer Eric Fossum set out to build a more efficient image sensor based on complementary metal oxide semiconductors (CMOS), which are microelectronic transistors that had been integral to computers since the 1960s. It had been tried before, but Fossum and his team figured out how to correct for noise that plagued earlier versions.

To develop the sensors, JPL entered into several Technology Cooperation Agreements with companies, including dental device manufacturer Schick Technologies of Long Island City, New York, which wanted to use them for dental X-rays. Engineers from Schick and JPL worked together to advance the technology and adapt it to X-ray imaging.

In 1995, Fossum and colleagues founded Photobit with an exclusive license for CMOS imaging, and Schick obtained an exclusive license for CMOS dental imagers.

What came to be called the active pixel sensor was more energy-efficient than CCD imagers, which was important for imagers Schick wanted to power with batteries. Active pixel sensors also allowed for smaller devices, which translated to patient comfort in imagers that are placed in the mouth. They were also less susceptible to electrical noise.

As CMOS sensors came to dominate the entire digital imaging industry, Schick, now owned by Sirona Dental Systems, benefited from rapid improvements in size, speed, memory, and quality, as well as cheaper mass production.

Today any company using CMOS dental image sensors has licensed the technology from Sirona, which still holds the license from JPL’s managing entity, the California Institute of Technology.