A family of pixel detector read-out chips for particle imaging and detection developed by the Medipix Collaborations

The family of Medipix and Timepix read-out chips represents one of CERN’s most successful technology-transfer cases. Developed with the support of four successive Medipix Collaborations involving a total of 37 research institutes, the technology is inspired by the high-resolution hybrid pixel detectors initially developed to address the challenges of particle tracking at the LHC. In hybrid detectors, the sensor array and the read-out chip are manufactured independently and later coupled by a bump-bonding process: this means that a variety of sensors can be connected to the Medipix and Timepix chips, according to the needs of the end user.

The first Medipix chip produced in the 1990s by the Medipix1 collaboration was based on the front-end architecture of the Omega3 chip used by the half-million pixel tracker of the WA97 experiment, but included a counter per pixel: this demonstrated that the chips could work like a digital camera capable of both detecting and counting each individual particle, providing high-resolution, high-contrast, noise hit free images and making them uniquely suitable for medical applications. The successive  collaborations gave rise to  the improved Medipix 2 and 3 chips and the Timepix 2 and 3 chips, with Medipix 4 under development.

One of CERN’s most successful technology transfer cases

Medipix and Timepix chips find applications in widely varied fields – from medical imaging to cultural heritage, space dosimetry, material analysis, education, and the industrial partners and license holders commercialising the technology range from established enterprises to start-up companies.

Medical imaging is at the heart of the Medipix technology and one of its direct applications. One of the most successful cases is the 3D colour X-ray scanner developed by MARS Bioimaging Ltd, using the Medipix3 technology, and which has been widely talked about since 2018. The colour X-ray imaging technique provided by Medipix3 produces clearer and more accurate pictures that should help doctors give their patients more accurate diagnoses. In 2021, the scanner arrived in Europe, at Lausanne University Hospital (CHUV) in Switzerland, as part of the international clinical trials to obtain the certifications allowing its medical use.

Associated technologies to have stemmed from the collaboration include the Timepix, Gempix and the VELOpix chip, which have led to new solutions in the high energy physics field. Investments made primarily for Knowledge Transfer have reaped important benefits for CERN’s baseline programme.