Mechanical　assessment　of　the　human　skin　is　critically　important　for　clinical　diagnosis　and　treatment　of　disease.　Past　works　developed　a　conformal　piezoelectric　system　(CPS)　that　enables　the　noninvasive　in　vivo　measurement　of　the　elasticity　modulus　of　the　skin,　and　a　mechanical　model　based　on　the　mechanism　of　out-of-plane　extension　of　the　capacitor-type　structures.　Here,　we　present　a　new　theoretical　model　that　is　established　based　on　the　mechanism　of　the　in-plane　deformation.　The　study　on　both　the　free-standing　CPS　and　the　CPS　mounting　to　the　polydimethylsiloxane　(PDMS)　target　substrates　verified　the　universality　of　the　new　model.　The　experimental　and　theoretical　results　consistently　show　that　the　output　voltage　of　the　first　sensor　approximately　linearly　increases　with　the　increase　of　not　only　the　applied　voltage　but　also　the　modulus　of　the　PDMS.　The　optimal　usage　mode　of　the　CPS,　in　which　the　voltage　is　applied　to　all　actuators　simultaneously,　is　proposed　for　the　measurement　of　the　elastic　modulus　of　target　substrates　such　as　skin.　(c)　2022　Elsevier　Ltd.　All　rights　reserved.