• ActiveTwo

  • Next Generation Active EEG System - from 16 - 256 channels

  • Product No: NS-1000
  • Manufacturer: Biosemi
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The BioSemi ActiveTwo system is equipped with up to 280 channels, a DC amplifier and 24-bit resolution, setting world-leading standards for multi-channel, high resolution, biopotential measurement systems for research applications. The ActiveTwo system is a further development of the successful ActiveOne system, which was the first commercially available system with active electrodes. Advances in technology have allowed BioSemi to significantly increase the number of channels, digital resolution, input range, and sample rate, without any increase in size, power consumption or costs. The second-generation active electrodes are smaller in size with less cable weight, while offering even better specs in terms of low-frequency noise and input impedance. The BioSemi ActiveTwo system upholds superiority over competing designs.


System Features

  • Up to 256+8+2 channels in a single box.
  • Second generation active electrode: smaller size, less weight and strain-relief.
  • Flexible coloured electrode labelling system.
  • 24-bit ADC per channel, unsurpassed S/N ratio and linearity.
  • Improved digital resolution, LSB value is 31nV.
  • Full DC operation, the largest input range in the industry (524mVpp).
  • User-selectable sample rate, high sampling available.
  • Full range of auxiliary sensor inputs available.

The BioSemi ActiveTwo system is fast to set up and does not require skin preparation for achieving reliable measurement. The ActiveTwo system is compatible with MEG/MCG and suitable for EEG, ECG as well as EMG measurements, allowing graphical programming (LabVIEW) on PC and Mac. The ActiveTwo is battery powered with high-speed fibre optic data transfer, which makes the subject fully optically and galvanically isolated from any mains. The BioSemi ActiveTwo system is specifically designed to be used in research applications only. The system benefits from freely configurable hardware and completely open-source software.


Technical Specifications


Sample-rate options: 2048 Hz 4096 Hz 8192 Hz 16,384 Hz
Max. number of channels at selected sample rate: 256 128 64 32
Bandwidth (-3dB): DC - 400 Hz DC - 800 Hz DC - 1600 Hz DC - 3200 Hz
Absolute sample rate accuracy (over temp range: 0-70 C): 0.1 Hz 0.2 Hz 0.4 Hz 0.8 Hz
Total input noise (Ze < 10 kOhm): 0.8 uVRMS 1.0 uVRMS 1.4 uVRMS 2.0 uVRMS
Full bandwidth: (5 uVpk-pk) (6 uVpk-pk) (8 uVpk-pk) (12 uVpk-pk)


System Specifications

Low-pass response:
5th order sinc digital filter
1/f noise (Ze < 1 MOhm):
1 uVpk-pk @ 0.1..10Hz
Channel separation:
> 100 dB
Leakage current, single fault:
< 50 uArms
High-pass response:
Fully DC-coupled
Amplifier current noise:
< 30 fArms
Common Mode Rejection Ratio:
> 80 dB @ 50 Hz
Trigger inputs:
16 inputs on optical receiver
(isolated from subject section), TTL level
24 bits, 4th order Delta-Sigma modulator with 64x oversampling, one converter per channel
Input bias current:
< 10 pA per channel
Isolation Mode Rejection Ratio:
> 160 dB @ 50 Hz
Trigger outputs:
15 outputs on the optical receiver
(isolated from subject section), TTL level
Sampling skew:
< 10 ps
Input impedance Active Electrode:
300 MOhm @ 50 Hz (1012 Ohm // 11 pF)
Power Consumption:
4 Watt @ 256 channels
inversely proportional with the number of installed channels
PC interface:
Relative sample rate accuracy (jitter):
< 200 ps
DC offset:
< 0.5 mV
Battery capacity, standard battery:
25 Watt-hour, 3 cell sealed lead-acid
(double capacity battery is available as an option)
Size of front-end, including battery-box (H x W x D):
120 x 150 x 190 mm
LSB = 31.25 nV, guaranteed no missing codes
DC drift:
< 0.5 uV per degree Celsius
Battery life on standard battery:
> 5 hours @ 256 channels
inversely proportional with the number of installed channels
Weight of front-end, including battery-box:
1.1 kg
Gain accuracy:
Input range:
+262 mV to -262 mV
Battery charge time (with external fast charger):
< 3.5 hours for a 100% charge
Environment: Indoor use
Temperature: +10°C to +40°C
Humidity: 30 to 75%
Pressure: 700 hPa to 1060 hPa
Anti aliasing filter:
fixed first order analog filter, -3dB at 3.6 kHz
< 0.1 %
Leakage current, normal operation:
< 1 uA rms.
3 years (1 year on electrodes and batteries)

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Please note: Important! This product is for research applications only. Not a medical device as defined in EU directive 93/42/EEC. Not designed or intended to be used for diagnosis or treatment of disease.