ActiveThree is the next generation of biopotential measurement systems for scientific research. ActiveThree's signal quality surpasses any EEG system currently available thanks to cutting-edge analog-to-digital converter technology. BioSemi's third-generation active electrodes and amplifier system - the ActiveThree - combines unsurpassed signal quality, portability, low power consumption, and ease of use.
ActiveThree can come configured with up to 142 channels of EEG/EXG electrodes and sensors. All 142 channels are fully DC-coupled and equipped with a novel 24-bit SAR (successive approximation register) A/D converter. This is the latest ADC technology available on the market, allowing for the highest signal quality with high interference suppression, offering a clean frequency spectrum. New low-voltage components further allow for low power consumption compared to its predecessors. As a result, a much smaller-sized battery is used, leading to a decrease in both the size and weight of the main AD-box. Additionally, the battery can be purchased anywhere locally, as it is a standard single battery cell. Auxiliary sensors such as respiration belts, GSR/EDA sensors, and response switches are now automatically detected and configured by the system. Last but not least, the CMS/DRL circuitry has improved in interference suppression.
The auxiliary sensor inputs on the ActiveThree have been completely resigned with six highly versatile inputs. No matter the type of sensor, auxiliary sensors can selectively be connected to any of the six auxiliary inputs. ActiveThree auto-detects the connected sensor and transmits the correct configuration to ActiView acquisition software. ActiView automatically updates the display to show and record data from the connected sensors, without the need to manually configure the sensor. Available auxiliary sensors include:
ActiveThree features up to 16 independent trigger inputs (IN) and 16 outputs (OUT) on the USB receiver’s 37-pin Sub-D connector. Inputs accept 3.3V TTLlogic (with 10kOhm pull-up resistors). All trigger lines are isolated from the AD-box, EEG/EXG electrodes and sensors. Works with nearly any stimulation presentation software (Presentation, E-Prime, PsychoPy, Inquisit, ...) through a trigger interface such as the MMBT-S from NEUROSPEC.
ActiView for ActiveThree can stream from its ring buffer over TCP/IP (e.g., for MATLAB clients) for online analysis and control. ActiView (V103 and newer) incorporates LSL-Streaming.
ActiveThree was designed with lightweight and portability in mind. By carefully selecting novel electronic components, the ActiveThree circuitry was designed with a quarter of the power consumption (both supply voltage, as well as current consumption, are halved) compared to the ActiveTwo. None of these new components compromise the performance of the ActiveThree. This allowed for the use of a smaller and more lightweight battery, decreasing both the size and weight of ActiveThree's AD-box. ActiveThree comes in a form factor of 162 x 149 x 62 mm and a mere 800g.
Compared to its predecessor, ActiveThree's sampling rate can now be adjusted within ActiView acquisition software. ActiveThree records and transmits all signals on the maximum (fixed) sample rate of 16,384 Hz and a bandwidth of 5.4 kHz. Down-sampling can be performed in ActiView software to a minimum of 256 Hz. ActiView uses a 5th-order CIC decimation filter when down-sampling to prevent aliasing. The bandwidth of down-sampled data is 1/5th of the selected sample rate.
ABR (auditory brainstem response) electrodes interface directly with ActiveThree through the six universal auxiliary inputs. The ABR active electrode circuitry has been improved and now features lower noise and a wider bandwidth compared to its predecessor. The high-pass frequency is set to 10 Hz and low-pass frequency is increased to 5.4 kHz.
BioSemi’s ActiveTwo has been extensively used in TMS–EEG for mechanistic, clinical, and methods work. The active electrodes from BioSemi are fully protected against electrostatic discharge (ESD). Users need not adopt special handling procedures to safeguard against damage from static electricity. All three models (ActiveTwo, Active2.5, and ActiveThree) AD-boxes are engineered to withstand TMS pulses without input circuitry degradation or signal corruption.
To maintain signal integrity during EEG acquisition, the following environmental constraints are advised at the subject site:
Exceeding these thresholds may introduce noise, interference, or measurement artifacts, thereby compromising signal quality.
ActiveThree is the direct successor, designed with TMS-pulse protection and the same optical isolation/active-electrode architecture, making it suitable for the same applications as publications transition to the newer hardware. Below a list of peer-reviewed publications show-casing the ActiveTwo used in TMS studies.
Clinical neurophysiology (schizophrenia): 64-channel ActiveTwo at 1024 Hz during single-pulse TMS to characterize cortical responses and connectivity alterations. Demonstrates feasibility and data quality in patient cohorts. https://academic.oup.com/cercorcomms/article/1/1/tgaa013/5828215
Artifact physics & early response access: Methods paper modelling TMS-evoked discharge artifacts; explicitly includes data from an active (BioSemi) EEG system and shows principled artifact removal to reveal responses a few milliseconds post-pulse. Widely cited in TMS–EEG preprocessing pipelines. https://pmc.ncbi.nlm.nih.gov/articles/PMC6063435/
Cognitive TMS–EEG (parietal timing/TEPs): J. Neurosci. study noting that the BioSemi ActiveTwo has been used previously for TMS–EEG (citing Levit-Binnun et al., 2010) and is designed to accommodate TMS effects—evidence of acceptance in high-impact cognitive work. https://www.jneurosci.org/content/jneuro/32/35/12258.full.pdf
The ActiveThree system is seamlessly integrable with Shimadzu’s LIGHTNIRS, enabling high-resolution, multimodal neuroimaging by combining EEG and functional near-infrared spectroscopy (fNIRS). This powerful integration allows researchers to simultaneously capture fast electrophysiological activity and slower hemodynamic responses, delivering a comprehensive view of brain function with millisecond and second-scale precision. The systems are fully synchronized via a dedicated hardware sync interface, ensuring precise temporal alignment between EEG and NIRS data streams. NEUROSPEC offers a purpose-built EEG-NIRS combined cap, ensuring optimal sensor positioning and participant comfort. Furthermore, a dedicated data merger tool is available to combine raw EEG and NIRS recordings into a single synchronized file, allowing for streamlined analysis and multimodal processing within your existing workflows. This seamless integration expands the research possibilities for cognitive neuroscience, developmental studies, and brain-computer interfaces.
Important Note: This product is for research applications only. Not a medical device as defined in Regulation (EU) 2017/745 (EU MDR), Swiss Medical Devices Ordinance (MedDO, SR 812.213), or FDA 21 CFR Part 860. Not designed or intended to be used for diagnosis, treatment of disease or any other medical purposes.
