Choosing an fNIRS System: NIRx or Artinis

We distribute both NIRx and Artinis in Israel. That is unusual, and it is the reason this post exists. A manufacturer comparing itself to a competitor is writing marketing. We sell both, so the comparison below costs us nothing either way.

First, is fNIRS the right measure

fNIRS measures the haemodynamic response, the same signal as fMRI, using near infrared light through the scalp.

Choose fNIRS over EEG when you need to know where in the cortex, and when the subject has to move. Choose EEG over fNIRS when you need millisecond timing. ERP components live in a window fNIRS cannot see.

Choose fNIRS over fMRI when the subject cannot lie still, when the task is social or naturalistic, when you are testing infants, or when scanner time is the constraint. fMRI still wins on depth and on whole brain coverage. fNIRS reaches cortex, not deep structures.

The combination we install most often is fNIRS with EEG, for exactly this reason.

Short separation channels

Ask about this before anything else. It is the question that separates buyers who have run fNIRS from buyers who have read about it.

Near infrared light passes through scalp and skull twice before it returns to the detector. A large part of what you measure is skin blood flow, not brain. Short separation channels sit close to the source, sample the superficial layer only, and let you regress that contamination out.

Without them, systemic changes in heart rate, blood pressure and skin perfusion sit in your data looking like task activation. Reviewers know this now.

One correction to something we hear on the phone often. This is not one manufacturer's feature. BOTH do it. NIRx offers 8 mm short distance detectors with full array head placement, up to 16 on a single NIRSport2 and up to 80 across connected devices. Artinis gets there through the flexible inter optode distance on the Brite, 10 to 55 mm, plus an SSC splitter that adds up to 8 more without costing you many standard channels.

If a quote you receive does not mention them at all, ask why.

How many channels, and where

Frontal only, 8 channels, is enough for prefrontal work. Executive function, working memory, and most of the applied and sports literature sit here. Brite Lite Frontal is 8 channels and does nothing else, which is the point of it.

The Brite gives up to 27 channels from a configurable optode template. That covers one region with a proper montage, whether that is motor, temporal or prefrontal with room to spare.

Above that you are in NIRx territory. A single NIRSport2 gives roughly 25 to 50 channels at the standard 3 cm separation and scales from 8 to 80 sources and 8 to 80 detectors, with the base device at 8 by 8 or 16 by 16. Three connected devices give a 48 source and 48 detector arrangement, which is where diffuse optical tomography and image reconstruction start to be possible.

3 cm is the standard adult source to detector separation. Infants need shorter, which is why paediatric systems exist as separate products rather than as a setting.

NIRx or Artinis

Density and scalability – NIRx. 8 to 80 sources and detectors, up to 5 devices fully synchronised.
Wearability and setup speed – Artinis. The Brite MKIV weighs 300 grams and attaches to the headcap.
Inside the MRI – NIRx. NIRxBorealis couples up to two NIRSport2 devices with fibre optodes, laser illumination and APD detectors.
Infants and toddlers – Artinis. BabyBrite for young babies, Brite Lite Frontal at 8 channels for prefrontal work with small children.
A CE marked medical device – Artinis. MediBrite is CE marked under MDR (EU) 2017/745, and Artinis calls it Europe's first medical NIRS device. NIRx systems are research devices, not for clinical diagnosis.
Large scale hyperscanning – Artinis. Brite Connect Ultra monitors up to 30 Brite devices from one screen. NIRx synchronises up to 5 devices and states 10 or more subjects over a wired network.
Analysis – a draw, and it depends on who is doing it.

How we advise, and this is our opinion and not a fact.

Buy NIRx if the paper you want to write has an image in it. Density, source reconstruction, MRI compatibility, and Satori as an analysis path a student can use without writing code.

Buy Artinis if the constraint is the participant. Infants, toddlers, patients, athletes mid movement, or thirty people in a room at once. With a two year old, the setup time is the whole experiment.

Buy both if you run a group that does both, which several Israeli labs now do.

And if what you are running is a prefrontal working memory task on 30 healthy adults, you need neither flagship. Tell us that is the paradigm and we will quote you the small system, not the big one.

Analysis, before you buy the hardware

Decide the pipeline first. It constrains the purchase more than people expect.

.snirf is the standard export format and it is what keeps you portable. Artinis Brite Connect exports it for downstream work in Homer or MNE Python. NIRx Satori, developed with Brain Innovation and distributed by NIRx, covers GLM, multi subject analysis, 2D and 3D visualisation and Python integration with no programming at all, which counts if the person doing the analysis is a first year student.

If your lab already runs Homer3, NIRSTORM or FieldTrip in MATLAB, say so in the quote request. It changes the recommendation.

Triggers and synchronisation

Both families support Lab Streaming Layer, so events stream from E-Prime or PsychoPy directly. NIRSport2 also takes a cabled trigger input. Brite Connect accepts events from a keyboard press, a PortaSync, or the button on the device.

If you are combining fNIRS with EEG, decide early which system is the timing master. Doing this after both are installed is painful.

The hair problem

Near infrared light does not pass through dense dark hair well, and signal quality on posterior sites drops accordingly.

It used to be that nobody wrote this down. Both manufacturers now address it. NIRx ships variable tension spring holders for scalp coupling. Artinis added multi power gain control to the Brite MKIV, four power levels plus an automatic setting, aimed at different skin tones and hair types, along with spring optode holders for temporal, parietal and motor sites.

It is better than it was. It is not gone. Frontal montages avoid it entirely. For whole head work, budget preparation time for optode combing and expect to lose some channels. Ask us about optode design before you assume a montage will work on your subject population.

Buying fNIRS in Israel

NBT is the Israeli distributor for both NIRx and Artinis. We install, train and support here, Sunday to Thursday, on site when needed.

Send us the paradigm, the population and the analysis pipeline. Those three decide the system, and we will tell you which of the two we would put in your lab and why we would leave the other one out. What are you running?