The CERN chips transforming science and society

Medical imaging, radiotherapy, space dosimetry, material analysis. These are just a few of the many areas that have been impacted by advanced semiconductor chips developed in recent decades by the Medipix collaborations at CERN in conjunction with over 30 external research institutes.

Hybrid pixel detectors were originally developed in CERN's microelectronics group in the early 1990s to make sense of the complex events foreseen at the future Large Hadron Collider. Medipix and its offshoot Timepix grew out of this effort and have become one of CERN's most successful knowledge transfer cases, triggering a significant number of commercial activities in widely differing application areas.

A symposium held at CERN on 23 September to mark the 20th anniversary of the Medipix3 collaboration showed that Medipix and Timepix still have much in store.

"Since the launch of the first informal Medipix collaboration in the mid-1990s, our collaborations have grown and so have the capabilities of our chips. With the latest version, Medipix4, offering a higher count rate, a larger detection area and a larger dynamic range, our collaborators can access the most advanced high-resolution photon counting chip in the world," said Medipix spokesperson Michael Campbell.

Chips comprising 2D arrays of silicon pixels are the basis of every smartphone camera, where electrical charge induced by the light incident on each pixel is first integrated and then read out. Medipix chips perform a similar feat at very high rates, but in this case by detecting the pulses induced by incoming charged particles one by one. This provides minimal image blurring, a requirement to track the complex debris emerging from high-energy particle collisions.

Initially focused on simply counting photons, the Medipix technology has advanced through several stages to bring higher energy resolution and improved count rates. Adding on-pixel timing information led to the birth of the Timepix chips, which triggered a range of new application areas while remaining core to current and planned particle physics experiments.

The first and most longstanding licensee within the Medipix collaboration is Malvern Panalytical, which has used Medipix2 and Medipix3 chips to create solutions for material analysis both within scientific research and for industrial process and quality control. Speaking about the firm's 25 years of engagement with the collaboration, Malvern Panalytical's Roelof de Vries said: "The most important lessons learned from our company, to turn a research development into a commercial product, is to be patient, constructive and supportive, and also willing to collaborate with the Medipix team to make improvements or to suggest improvements."

One of the notable Medipix applications is the 3D colour X-ray scanner developed by MARS Bioimaging Ltd, which helps doctors give their patients more accurate diagnoses. This year, the scanner entered clinical trials at the Hospital for Special Surgery in New York. Anthony Butler of MARS Bioimaging emphasised that these machines are created to take imaging technology out of the hospital and put it in the community. "So, we're not just providing better images, we're making our healthcare more accessible and more affordable for people."

Other cutting-edge applications of Timepix showcased during the symposium included the monitoring of radiation levels during space travel, the charting of progress in radiotherapy treatment in cancer patients, and quantum imaging, to mention just a few.

Attendees also heard from the first teacher to use Timepix detectors in the classroom to show STEM (science, technology, engineering and mathematics) students the levels of radiation in the world around them. The teacher in question, Becky Parker, sees Timepix devices in school replacing the Geiger counter as the mechanism by which students understand radiation: "We've looked at bananas, Brazil nuts, tea. We didn't realise how different soils and fertilisers affect the radiation level of tea, which you might not consider was a thing. I think if we can expose students to this cutting-edge technology, it's far more effective for young people understanding radiation than using old technology."

Many of the symposium presentations were given not by members of the Medipix collaboration nor even by the commercial licensees, but rather by clients of the licensees. This shows that successful dissemination of technology from high-energy physics to other fields relies on developing enduring partnerships with commercial players, be they startups or more established companies.

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