Infrared plethysmography is one of the most available, cost-effective and user-friendly methods for visualizing pulse-synchronous fluctuations in tissue volume, based on an optical measurement method on the body surface.

In medical diagnostics, this technique is used to measure the heart rate or pulse curve and is also the basis for continuous measurement of oxygen saturation in the blood (pulse oximetry).

In addition to the physical principles and electronic circuit design, hardware and software-based signal filtering and signal amplification are key aspects in the acquisition and processing of biosignals. A finely tuned interaction of these components enables the generation of a high-quality signal (input), which can then be displayed on a monitor as a wave-shaped signal (output).

The generation of high-quality biosignals forms the basis for medical disease diagnostics and research into medical issues, today also using artificial intelligence methods.

Using finger plethysmography as an example, this presentation will explain biosignal generation from the electrotechnical setup to the visualized biosignal using the ADALM2000 module (Analog Devices, Boston, USA).