Data Acquisition Basics: Your Body as a Battery—How Are Physiological Signals Recorded?

During the process of physiological data acquisition, the human body behaves much like a battery. Electricity flows from parts of the body that are negatively charged to parts of the body that are positively charged, and this occurs constantly throughout all living tissue.

Since each physiological signal has a distinctive electrical signature, we can place electrodes at the appropriate points on the body and accurately record the electrical activity of the desired signal. Modern data acquisition systems (such as the MP160 or MP36 systems) convert these analog signals into digital waveforms that can be displayed onscreen via life science software such as AcqKnowledge or Biopac Student Lab.

When acquiring physiological data, it’s important to understand the distinction between biopotential and transducer signals. Biopotential signals are electrical signals acquired directly from the body via electrodes, as previously referenced in the “human battery” analogy. Examples of biopotential signals are heartbeat (ECG), brain activity (EEG), muscle activity (EMG), eye movement (EOG),  and gastric system (EGG). Transducer signals differ from biopotential signals in that they are reliant on force, movement, or some other proportionate change, rather than electricity from the body. To measure these, the transducer itself provides a voltage signal which enables it to measure activity such as respiration/airflow, blood pressure, temperature, and grip strength. In all cases, the voltage signal produced by the transducer increases proportionately with the force, movement, or temperature exerted upon it. This affects the contour and appearance of the onscreen waveform.

Whether recording biopotential or transducer signals, both offer a glimpse into the varied and complex workings of the human body.

BIOPAC offers a wide array of wired and wireless equipment that can be used in your research. To find more information on solutions for recording and analyzing signals such as ECG, heart rate, respiration and more using any platforms mentioned in this blog post, you can visit the individual application pages on the BIOPAC website.