ActiveTwo

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

Configurations

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
Digitalization: 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: USB2.0
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
Quantization-resolution: 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: 1%	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	Distortion: < 0.1 %	Leakage current, normal operation: < 1 uA rms.	Warranty: 3 years (1 year on electrodes and batteries)

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