Humidity　sensors　have　received　considerable　attention　in　recent　years　because　of　their　significance　and　wide　applications　in　agriculture,　industries,　goods　stores,　and　medical　fields.　However,　the　conventional　humidity　sensors　usually　possessed　a　complex　sensing　mechanism　and　low　sensitivity　and　required　a　time-consuming,　labor-intensive　process.　The　exploration　for　an　ideal　sensing　material　to　amplify　the　sensitivity　of　humidity　sensors　is　still　a　big　challenge.　Herein,　we　developed　a　simple,　low-cost,　and　scalable　fabrication　strategy　to　construct　a　highly　sensitive　humidity　sensor　based　on　polymer/gold　nanoparticle　(AuNP)　hybrid　materials.　The　hybrid　polymer/AuNP　aerogel　was　prepared　by　a　simple　freeze-drying　method.　By　taking　advantage　of　the　conductivity　of　AuNPs　and　high　surface　area　of　the　highly　porous　structure,　the　hybrid　poly-N-isopropylacrylamide　(PNIPAm)/AuNP　aerogel　showed　high　sensitivity　to　water　molecules.　Interestingly,　the　hybrid　PNIPAm/AuNP　aerogel-based　humidity　sensor　can　be　used　to　detect　human　breath　in　different　states,　such　as　normal　breath,　fast　breath,　and　deep　breath,　or　in　different　individuals　such　as　persons　with　illness,　persons　who　are　smoking,　and　persons　who　are　normal,　which　is　promising　in　practical　flexible　wearable　devices　for　human　health　monitoring.　In　addition,　the　humidity　sensor　can　be　used　in　whistle　tune　recognition.　©　2018　American　Chemical　Society.