A strain sensor for sensing strain along a first axis and a second axis, the strain sensor comprising: (i) a first elastic strain sensor comprising an elastic material having two or more channels, each channel extending from a first end to a second end, parallel to a first strain axis; at least one loop portion connecting the first end of a first channel to the first end of a second channel, wherein the loop portion has a larger cross-sectional area along an axis transverse to the first strain axis; and a conductive liquid extending continuously from at least the second end of the first channel, through the loop portion, to the second end of the second channel; wherein the first strain axis extends along the first axis; and (ii) a second elastic strain sensor comprising an elastic material having two or more channels, each channel extending from a first end to a second end, parallel to a second strain axis; at least one loop portion connecting the first end of a first channel to the first end of a second channel, wherein the loop portion has a larger cross-sectional area along an axis transverse to the second strain axis; and a conductive liquid extending continuously from at least the second end of the first channel, through the loop portion, to the second end of the second channel; wherein the second strain axis extends along the second axis; and wherein the elastic material of the first elastic strain sensor is bonded to a top surface of the elastic material of the second elastic strain sensor such that the first elastic strain sensor is provided in a first layer and the second elastic strain sensor is provided in a second layer whereby the first elastic strain sensor overlaps at least a portion of the second elastic strain sensor and the first axis intersects the second axis. (i) a first elastic strain sensor comprising an elastic material having two or more channels, each channel extending from a first end to a second end, parallel to a first strain axis; at least one loop portion connecting the first end of a first channel to the first end of a second channel, wherein the loop portion has a larger cross-sectional area along an axis transverse to the first strain axis; and a conductive liquid extending continuously from at least the second end of the first channel, through the loop portion, to the second end of the second channel; wherein the first strain axis extends along the first axis; and an elastic material having two or more channels, each channel extending from a first end to a second end, parallel to a first strain axis; at least one loop portion connecting the first end of a first channel to the first end of a second channel, wherein the loop portion has a larger cross-sectional area along an axis transverse to the first strain axis; and a conductive liquid extending continuously from at least the second end of the first channel, through the loop portion, to the second end of the second channel; (ii) a second elastic strain sensor comprising an elastic material having two or more channels, each channel extending from a first end to a second end, parallel to a second strain axis; at least one loop portion connecting the first end of a first channel to the first end of a second channel, wherein the loop portion has a larger cross-sectional area along an axis transverse to the second strain axis; and a conductive liquid extending continuously from at least the second end of the first channel, through the loop portion, to the second end of the second channel; wherein the second strain axis extends along the second axis; and an elastic material having two or more channels, each channel extending from a first end to a second end, parallel to a second strain axis; at least one loop portion connecting the first end of a first channel to the first end of a second channel, wherein the loop portion has a larger cross-sectional area along an axis transverse to the second strain axis; and a conductive liquid extending continuously from at least the second end of the first channel, through the loop portion, to the second end of the second channel;