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Physics Professor Co-invents New Low-cost Nanofilm Radiation Detector

Technology Can Be Used in Diagnostic Imaging, Medical Dosimetry and Homeland Security

Radiation detector
The detector can be printed on a rigid substrate like glass or on a flexible polymer sheet, as shown.

By Edwin L. Aguirre

Prof. Erno Sajo of UMass Lowell’s Department of Physics and Applied Physics, in collaboration with researchers from Brigham and Women’s Hospital in Boston led by Prof. Piotr Zygmanski, has developed a new class of inexpensive nanofilm radiation detectors that can be used in everything from health care to homeland security. The device uses thin-film sensors to harness the energy of the radiation it detects to power itself.

“Unlike existing technology, the detector does not need an external power supply or even signal amplification to operate,” says Sajo, who is an expert in medical physics and radiological science. “Another important property is that it is flexible, able to conform to curved shapes while being largely transparent to radiation. The detector’s cost per unit area is only a fraction of that of current detectors. Depending on the detector’s resolution and application, the cost to fabricate the detector array can range from a few dollars to several hundred dollars per square feet.”

Sajo says nanofilms, measuring only a few billionths of a meter in thickness, are suitable for a variety of applications, from national security and nondestructive testing to medical imaging and cancer treatment.

Flexible radiation detector
The photo shows a prototype of the new radiation detector being developed by Prof. Erno Sajo and his co-researchers. The sensor (dark brown) measures approximately one square inch and a few hundred nanometers thick.
He says the detector can be used to monitor radiation in nuclear power plants and aboard nuclear-powered Navy aircraft carriers and submarines. It can also be used to identify and map areas contaminated with radioactive materials.

“In medicine, it can replace or augment existing radiation detectors that are part of fluoroscopy systems and image-guided radiotherapy in hospitals. In a CT scanner, it can tell the patient’s dose to X-rays. It can also monitor the radiation sources used in the treatment of prostate cancer,” says Sajo.

“When fully developed, this device has the potential to be implantable in living patients, one that will wirelessly transmit its signal to simultaneously tell doctors its exact location in the body as well as the radiation dose it receives in real time, while the radiation beam is targeting the tumor. In this way, movement of the patient’s organs will no longer affect the beam’s targeting precision,” he adds.

Erno Sajo portrait Photo by Edwin L. Aguirre
Prof. Erno Sajo directs the university’s medical physics program. He studies the fundamental interactions between radiation and biological matter, with particular emphasis on cancer therapy.
The project has been supported by the university’s Office of Technology Commercialization, which provided the seed grant to enable Sajo to fabricate the next-generation prototypes. UMass Lowell and Brigham and Women’s Hospital have filed a patent jointly and founded a new startup company, RayWatch Inc., to commercialize the technology. The company, which is based in the Innovation Hub at 110 Canal St. in Lowell, has recently been awarded a Phase II SBIR grant from the U.S. Air Force. Matt Gagne, the CEO of RayWatch, is a doctoral candidate in the medical physics program at UMass Lowell.

The Thinner, the Better

The sensor can detect the type and intensity of ionizing radiation as well as the location of its emission in a single instrument, and it employs simple electronics to report digital signals that may be transmitted wirelessly, Sajo explains.

“The device is also scalable, meaning we can create the sensor in any size, from a fraction of a square inch to many square feet in area, and operate it either in pixelated array or as a single continuous sheet,” he notes.

“The nanofilm sensor’s efficiency actually increases with decreasing thickness,” Sajo adds. “The best performance is achieved when the sensor is organized in layers of a few hundred nanometers each.”