Optional sensors for ActiveTwo permit measurement of a range of non-biopotential signals, including respiration, temperature, blood flow / pulse, skin conductance / skin resistance, force, acceleration, eye-position, ambient sound, light, and more.  In general, active electrodes are the best sensor for measuring any biopotential with ActiveTwo.

  • Respiration – A Nihon Kohden TR-753T respiration belt is provided with a cable wired for use with one of the three available circular DIN connectors on the ActiveTwo front panel.  Strong, reliable signals are produced, because the respiration belt uses the ActiveTwo system power supply.  An additional LabVIEW module is delivered with the system when a respiration belt is ordered.
  • Skin Conductance (GSR) – With this ActiveTwo accessory, the impedance of the skin can be measured.  The Skin Conductance option consists of 2 passive electrodes to induce an oscillatory signal exactly synchronized with the system’s sample-rate.  The skin conductance option is wired to one of three available circular DIN connectors on the ActiveTwo front panel. Because the skin conductance accessory uses “lock-in detection”, the stimulus-current can be as low as 1uA. The low-current and synchronized oscillator ensure that the biopotential measurements (EEG, EMG or ECG) are not corrupted by the skin conductance oscillator signal. An additional LabVIEW module for skin conductance is delivered with the system when skin conductance is ordered.
  • Temperature – With this high precision temperature sensor from HP (Agilent 21078A), skin temperatures can be measured.  The temperature sensor directly plugs into one of the three available circular DIN connectors on the front panel of the ActiveTwo A/D Interface Box. An additional LabVIEW module is delivered with the system when a temperature sensor is ordered.
  • Pulse / Plethysmograph – This Plethysmograph sensor from ADI instruments (MLT1020) uses an infrared photoelectric sensor to detect changes in tissue blood volume. The Plethysmograph sensor directly plugs into the front of the ActiveTwo. An additional LabVIEW module is delivered with the system when a Plethysmograph sensor is ordered. This sensor can be ordered with a finger clip (/F option), with a Velcro strap (/p option) or with an ear clip (see picture, /E option).
  • Jazz Vigilance Monitor – The Jazz vigilance monitor system was developed by a Polish academic research group, led by Prof. Ober.  A special ‘synchronic’ version is offered for interfacing directly with the ActiveTwo.  The synchronic Jazz system consists of 3 building blocks: 1) the head mounted eye monitor, 2) transmitter with twin fiber-optic connection (data out, sync in), and 3) receiver with twin fiber-optic connection and RS232 output.  Note that there is no head position/orientation monitoring capability, so Jazz cannot be used to derive ‘point-of-regard’ from eye-position, as would typically be possible with an eye-tracking system, unless the subject’s head is immobilized.  The sample-rate of Jazz is synchronized with the ActiveTwo sample rate via a sync connection between ActiveTwo receiver and Jazz receiver. The Jazz data interfaces to the ActiveTwo host PC via the RS-232 port.  The ActiView acquisition software combines the ActiveTwo data (via USB2 port) and Jazz data (via RS-232 port).
  • Active Strain Gage – BioSemi can equip your force transducer with a miniature (15x30mm) precision strain gage amplifier.  This makes your strain gage active.  The output signal is processed by the ActiveTwo A/D box just like any other active sensor. The advantages are that all influences of the connection cable are completely eliminated, there is no cable interference and there is no temperature drift.  The Active strain gage contains a low-noise, low-power, zero-drift, chopper-stabilized differential amplifier.  The power supply is from the ActiveTwo AD-box (16mA total bridge current). The modification to the Active strain gage can be performed for quarter, half and full bridge strain gage configurations. The supplied LabVIEW module automatically zeros the bridge and amplifier offset on startup.  No further hardware trimming is necessary.  The photo shows a precision force measurement for finger pressure, the amplifier is sealed in resin on the left side of the ergometer.  Note that the Active strain gage needs 2 extra channels
  • Microphone – Microphone to record audio stimuli and responses.  A highly effective built-in spherical filter minimizes wind and breath ‘pop’ noise.  Connects directly to the standard BioSemi ActiveTwo Ergo input on the AD-box.
  • Dual Response Switch – Response switches for direct connection to the AUX (front) connectors on the AD-box. The setup with the response switches connected directly to the AD-box ensures accurate timing of the response moments (pulse is mixed directly with the incoming EEG signals) as well as optimal isolation of the subject (no grounded equipment near the subject). Using the USB trigger port with a response box also provides good timing, but has the disadvantage of bringing the safety grounds near the subject. The BioSemi Response switches connected to the AD-box will make sure your response timing is accurate and your subject isolation remains optimal.