**Abstract**

In-home physiological monitoring devices enable the monitoring of vital health parameters and can facilitate health recovery. The current state of the art is inclined towards non-invasive technologies such as wearable mobile devices and patch-based sensors. In this chapter, we provide an overview of progress made in the field of dry electrodes for biopotential acquisition, based on their mechanistic principles, materials, testing methods, and effectiveness in a real-world setting. Important parameters affecting the dry electrode performance such as the area, material, applied pressure and skin hydration are discussed. Traditionally, the development and testing of these wearable electrodes are conducted empirically, *in vivo* on human skin. However, due to the inter- and intra-subject variability in human skin properties, reliability, repeatability, and the efficacy of the device under investigation cannot be evaluated. Thus a review is presented about the skin phantoms used to simulate the electrical properties of the skin, which has the potential to serve as a robust method to test the functionality of current and future electrodes. This retrospective overview provides researchers with an understanding of the mechanistic principle of biopotential electrodes and the crucial factors that affect electrode performance, thus facilitating wearable electrode development.

**Keywords:** dry electrodes, skin phantoms, biopotential signals, wearable devices, non-invasive, skin-electrode impedance
