Hydrogel‐Based 3D‐Printable Stretchable Pressure Sensor

ABSTRACT Soft pressure sensors become increasingly important, for example, to introduce tactility to soft robots, smart wearables, and biomedical devices. These applications often require stretchable sensors that withstand deformation. Conventional soft pressure sensors often entail concentrated fillers that tend to render them brittle, such that they risk failing if excessively strained. We introduce a 3D‐printable pressure sensor composed of carbon black‐functionalized double network granular hydrogels (CB‐DNGHs). The granular structure of DNGHs enables localization of CB fillers in the interstitial spaces such that they reach percolation even if added at concentrations as low as 0.95 vol%, enabling them to combine piezoresistivity with toughness. The granular nature of the ink offers an additional advantage: it enables direct ink writing of materials with locally varying compositions and hence pressure sensing ranges. We leverage this feature to 3D print a CB‐DNGH‐based shoe sole for gait analysis that can detect pressures as low as kPa to several 100 kPa. The combination of a wide pressure sensing range, high sensitivity, low signal drift, and high toughness renders this material a promising soft pressure sensor for underwater applications, point‐of‐care measurements, or measurements conducted in humid environments.