Strain sensor unit and skin sensor module comprising the same

A skin sensor module comprising:

• a substrate having a plurality of through-holes;
• and
• a plurality of strain sensor units located at the plurality of through-holes, respectively, each strain sensor unit comprising:
• a piezoelectric device located at one side of the through-hole on the substrate, and extending toward another side of the through-hole;
• a piezoresistor located at another side of the through-hole on the substrate, and extending toward one side of the through-hole;
• a first electrode located on the piezoelectric device;
• and
• a second electrode located on the piezoresistor,
• wherein the piezoresistor overlaps with a whole or part of the piezoelectric device, and
• wherein the piezoresistor is a nanocrack-control based metal piezoresistive device.