Hydrogel sheet

A medical electrode hydrogel used to be placed between an electrode formed from a conductive material and a skin surface, the hydrogel comprising:

• a hydrogel sheet including a hydrogel, and
• a plurality of intermediate substrates embedded in the hydrogel, the plurality of intermediate substrates including a first intermediate substrate and a second intermediate substrate,
• wherein the first intermediate substrate has a stretch rate of 20% to 90% measured by the following measurement method:
• the first intermediate substrate having a 20 mm-width and a 100-mm length is clamped at 70-mm intervals in a length direction, the first intermediate substrate is stretched in the length direction at a stretch rate of 100 mm/min, and the length L (mm) of the first intermediate substrate between the clamps when the maximum load is applied is measured, the stretch rate (%) is calculated as [(L-70)/70]*100,
• wherein the second intermediate substrate has a stretch rate of 100% to 200%, the stretch rate of the second intermediate substrate being measured by the following measurement method:
• the second intermediate substrate having a 20 mm-width and a 100-mm length is clamped at 70-mm intervals in a length direction, the second intermediate substrate is stretched in the length direction at a stretch rate of 100 mm/min, and the length L (mm) of the second intermediate substrate between the clamps when the maximum load is applied is measured, the stretch rate (%) is calculated as [(L-70)/70]*100.