The McGill Physiology Virtual Lab

Biomedical Signals Acquisition

Computerized recording system
  In all the laboratory sessions concerned with the acquisition of electrophysiological data, we will use  a complete system that acquires, amplifies and transforms the signal into a digital one and sends it to the computer via a special port (USB).
It is of value to look at the different possible connections and ancillary equipment used for specific tasks.


Setup used in the first laboratory: the sine wave is generated by the waveform generator (left), which is connected via a "BNC" connector to one of the channels of the Powerlab unit, and then processed further by the hardware and software. Cables with special electrodes are also connected to the BioAmplifier (right): this isolated amplifier can be connected to a subject.

The signal acquisition system

Input (coaxial) BNC or 8-pin DIN connectors

Analogue input BNC connectors are used to record external signals, either directly, or by adding high impedance pre-amplifiers (as in the case of the resting membrane potential lab) . The 8-pin DIN connectors allow to record external inputs from signal conditioners, such as “pods”. The EOG pod uses the steady corneal-retinal potential to detect eye movement and position. It is electrically isolated and safe for human use (the EOG will not be demonstrated this year).

The trigger BNC connector allows for an external signal to synchronize recording with an external event. You will be using this feature during the Compound Action Potential lab. An external stimulator (Grass SD9) will be connected to this trigger and synchronization between recording and stimulation of the nerve will occur.

The Bio Amp input provides access to dual isolated differential amplifiers with a common ground- safe for human use in a teaching context-. The signals from this connector are recorded on input channels 3 and 4 of the Powerlab. Bioelectrical potential signals (EEG, EOG, ECG, EMG) can be recorded using the subject cable and lead wires supplied with the unit.


Click here to continue with the next section: the waveform acquisition