Skin stimulation and recording: Moving towards metal-free electrodes

Bioelectronic microfluidic wound healing: a platform for investigating direct current stimulation of injured cell collectives

“…33 The use of recently developed non-metal, supercapacitive hydrogel electrodes facilitates not only a compact design in this 2D assay work, but also ease of translation to more 3D architectures, and importantly, it is an enabling technology for translation into a clinically useful device. 38 However, it is of critical importance to focus on the electrode's charge storage limitations and the stimulation protocol's total charge to be delivered. The pseudocapacitor hydrogel electrode used here has a relatively high charge storage capacity (CSC ≃ 40 mC cm −2 to 50 mC cm −2 ).…”

“…The pseudocapacitor hydrogel electrode used here has a relatively high charge storage capacity (CSC ≃ 40 mC cm −2 to 50 mC cm −2 ). 38 This CSC is crucial for determining over how long the current can be delivered capacitively ( t = q / i , where q is the charge stored in the electrode and i is the input current) before it shifts to a predominately faradaic current, which is reliant on pH-shifting electrochemical reactions. This is why it is imperative to also account for the amount of pH buffering agent (molarity).…”

Bioelectronic microfluidic wound healing

“…The pseudocapacitor hydrogel electrode used here has a relatively high charge storage capacity (CSC ≃ 40 to 50 mCcm −2 ). 31 This CSC is crucial for determining over how long the current can be delivered capacitively ( t = q / i , where q is charge stored in electrode and i is the input current) before it shifts to a mostly faradaic current, which is reliant on pH-shifting electrochemical reactions. This is why it is imperative to also account for the amount of pH buffering agent (molarity).…”

“…The protocol for making the electrotaxis scratch device leverages using a common prototyping equipment (i.e., CO 2 laser) for both microfluidic adhesive structuring 30 and electrode fabrication 31 (Fig. 1 a,b, see Methods section for more details).…”

“…The fabrication of laser-induced graphene (LIG) electrodes coated with pure PEDOT:PSS hydrogels was recently established by our group. 31 In short, a (CO 2 ) laser (same as above) is used to carbonize a polyimide sheet (Kapton HN, 75 µm thick) with a rasterization protocol at 4.8 W and 15.2 mm/s. The freshly carbonized LIG was air plasma-treated (Femto, Diener Electronics) for 5 min at 100 W and 10 sccm to make it more hydrophilic and functionalizable.…”