Examples are generally described that include an array of micro-needles. A capillary may be coupled to the array of micro-needles and configured to receive fluid from at least a portion of the array. A conductivity sensor may be arranged to measure conductivity of the fluid within the capillary, and a pump may be arranged to move fluid through the capillary. A processor may arranged to receive signals indicative of conductivity from the conductivity sensor and identify a dehydration condition based at least in part on a change in the signals indicative of conductivity.
