We 3D printed small strips of hydrogel and evaluated the conductivity of each material (Figure ). As expected, increasing the conductive polymer (PEDOT:PSS) content results in increased conductivity. Meanwhile, the crosslinker (BIS) content seems to have no impact on conductivity. This finding highlights another advantage of utilizing conductive polymers; hydrogels that use ionic atoms, like common salts, as charge carries will have reduced conductivity with increased crosslinker concentration because the diffusion path of the ions becomes more convoluted. The conductive pathways provided by the conductive polymers presented here are unaffected by crosslinking density at the concentrations investigated. However, increased MC content does result in decreased conductivity to an extent. At higher MC concentrations, the effect seems to plateau and, beyond a certain threshold, increased MC content has minimal impact. The measurements shown in Figure use graphite felt electrodes with hexacyanoferrate (HCF) as a redox agent to accommodate mixed ionic conductivity. 55 If the printing characterization, mechanical characterization, and conductivity characterization are all considered together, the three components (PEDOT:PSS, MC, and BIS) can be used together to optimize material properties throughout the process. With the fabrication of soft electronics in mind, the conductivity of the material is a crucial property to consider. As expected, increasing the PEDOT:PSS content increased conductivity, but increased PEDOT:PSS also impacts every other material property, including the viscosity of the fluid ink, its rheological behavior, its printability, and the crosslinked hydrogel's stiffness. This can create a challenge for tuning conductivity without altering other desirable characteristics. Fortunately, the MC content can be tuned to optimize fluid rheological properties and significantly alter the extrusion printing properties with minimal impact on the resulting hydrogel's stiffness. Above a threshold, MC seems to have minimal impact on conductivity as well, although increasing MC content does initially result in decreasing conductivity values before reaching that threshold. Offering even more adaptability, the BIS content can be tuned to optimize hydrogel stiffness with negligible impact on any other characteristic examined, rheological behavior, printability, or conductivity. We hypothesize that general trends may hold true even when substituting different materials for the conductive polymer, the thickening agent, or the crosslinker. Some of these findings likely also transfer to other 3D printing methods. For example, conductivity may still be unaffected by crosslinking density when using direct light printing methods. While we focus on the impact of three components in this work, additional materials could contribute further advantages, especially to improve conductivity. For example, the addition of polypyrrol, polyacrylic acid, sulfuric acid treatment, ionic liquids, or other doping agents can greatly improve the conductivity of PEDOT:PSS materials in comparison to this work. Thermoannealing can also improve PEDOT:PSS material conductivity. Dehydration provides another factor that should be considered when developing iontronic hydrogels and is limited when the hydrogels are encased in PDMS or are submerged in water. Some applications, however, may want to further limit dehydration over long periods of use in dry environments. In such cases, glycerol, lithium chloride, or other hygroscopic materials can be used to maintain water or to even draw water from the air. High concentrations of lithium chloride, for example, would likely improve both conductivity and water retention of the PEDOT:PSS material presented. Our aim focused on understanding the contributions of the basic components without additional modifications beyond the 3D printing process. The understanding established by this characterization informed the composition of the ink that was then used for the rapid fabrication of advanced soft electronics.