Bernhard Zimmermann, the Man Behind the NINJA: One of BU’s Most Used fNIRS Devices
By Danny Giancioppo | Photos provided by Bernhard Zimmermann
The NinjaNIRS, or NINJA, is a wearable fNIRS helmet that has thrust the field of neuroscience into new heights, and which almost all Boston University graduate students affiliated with neuroscience subjects have come across in their research. In essence, this fNIRS innovation has allowed subjects’ whole heads to be tested while retaining mobility, allowing for “real world” brain function scans outside of a laboratory.
The technology is well known within the Boston University community. What not everyone knows, however, is who pioneered this instrument, and the continued fNIRS work he leads in the Neurophotonics Center and Bio Optical and Acoustic Spectroscopy (BOAS) lab: Bernhard Zimmermann, senior research scientist and electrical engineer.
From his childhood education in Zurich, pursuing a path in physics and math was always clear to Zimmermann. “Both because that interested me most, and that’s where I got the better grades.” Being drawn to electrical engineering during his time at ETH Zurich, he found an opportunity to develop a thesis working with the university hospital, focusing on fNIRS. A field which he described as feeling “more directly useful to people” to more theoretical or consumer-oriented technology studies.
While attaining his doctoral degree from MIT, Zimmermann worked as a research assistant at Massachusetts General Hospital, and began working with Neurophotonics Center Director David Boas in his lab. Now based in California, his primarily remote work spans all aspects of the BOAS lab, but his main research interests remain in fNIRS.
“My main project is in fNIRS,” Zimmermann says. “My role in the lab [involves] everything that has to do with systems engineering and electronics design.” Within the BOAS lab, Zimmermann goes on, there are “two sides” of research: microscopy and fNIRS. While Zimmermann leans toward the hardware side of fNIRS with fellow research scientists and graduate students, he does assist on the microscopy side as well.
“My research interests are basically to push both fNIRS instrumentation and […] speckle-based side of the research, which is measuring bloodflow,” he says. “My interest is in really pushing those forward and making them more accessible to users inside BU and outside as well.”
This drive is in some part what led to the creation of the NinjaNIRS wearable helmet in 2022, a project started all the way back in 2017 at BU. According to Zimmermann, fNIRS systems fifteen some-odd years ago were far more cumbersome, built into server racks and limiting its usability and accessibility for researchers and test subjects. Some time in the mid-2010’s, efforts to “shrink” the technology down to more mobile platforms through fiberless, portable models gained traction.
“When we came to BU we started playing with that,” Zimmerman says, “but our goal was always to push this to the limit and increase density. More importantly, what no one had commercially at that time was a whole-head system where you could image the whole cortex simultaneously, as opposed to in little patches.”
From these aspirations came the NINJA, which was not only one of the first wearable whole-head solutions, but remains an open system, accessible for free online––which was no mistake. Having an open system allows Zimmermann and team to adapt and iterate the system to evolving needs.
“It’s continuously evolving,” he explains. “It’s a very modular system, from the hardware. You have a main board, a back plane, and you have different plug-in boards for the sources and detectors.” The source hardware, he goes on, has already been upgraded before, and they aim to update to an even higher power in fall 2026. Similarly, the detectors are set to be upgraded to a new generation with internal amplification to increase sensitivity by another factor of ten.
“It’s another reason why it’s nice to have our own [technology] instead of a commercial,” Zimmermann says. “So we can drive.”
The NINJA is one of the best tools to measure brain function and activation, Zimmermann says, providing ideal opportunities for graduate students interested in not only studying, but advancing neuroscience fields. The whole-head utility of the instrument remains rather unique as compared to other fNIRS laboratories, and therefore offers a more detailed look into neurological function, development, and disorder studies.
This optimization further extends to the benefits fNIRS studies, Zimmermann goes on. As most fNIRS falls into convergent efforts to understand the brain, there are many complementary functions to the field of study, including helping to advance disease studies and more. What always helps, in matters of convergent research, is a community which uplifts collaboration and provides such opportunities. To Zimmermann, this is one of Boston University’s great strengths.
“BU is a very collaborative place,” he says. “Everyone is trying to help, if you reach out.” One of Boston University’s strengths is its student-led focus, he continues, which keeps new and interesting ideas afloat. “Also on the administrative side of BU, it is very supportive. People try to make things happen.”
This includes founding a collaborative relationship with NIRx, a company building fNIRS systems for the wider market. With their assistance, the team has been able to build multiple whole-head systems, which would not have been possible as an independent laboratory. “The supportiveness of BU […] to set up a functioning collaboration with a small to medium-size company,” Zimmermann praises, has been an invaluable resource.
Looking ahead, Zimmermann is pleased with the progress of the whole-head system, with two instruments at BU, another at a collaborating lab at TU Berlin, and another at Northeastern University. The ultimate goal when designing such technology, after all, is to make a difference through hands-on experiences.
“The ideal when you design [these systems] is to have some impact, by actually having people use it,” he says. “It has been great to have the opportunity to do that in the Neurophotonics Center and the BOAS lab.”