This　work　describes　a　novel　and　portable　pressure-based　point-of-care　(POC)　testing　strategy　for　the　sensitive　and　rapid　detection　of　carcinoembryonic　antigen　(CEA)　via　a　flexible　pressure　sensor　constructed　by　three-dimensional　(3D)　polypyrrole　(PPy)　foam.　Initially,　platinum　nanoparticles　(PtNPs)　were　conjugated　to　the　detection　antibodies,　which　were　used　to　form　sandwich-type　immunocomplexes　with　targets　and　capture　antibodies　in　the　reaction　cell.　Then,　the　carried　PtNPs　catalyzed　the　dissociation　of　hydrogen　peroxide　(H2O2)　for　the　generation　of　oxygen　(O2)　in　a　sealed　device,　translating　the　biomolecule　recognition　event　into　gas　pressure.　With　the　increase　of　pressure,　a　flexible　pressure　sensor　with　3D　polypyrrole　foam　as　the　sensing　layer　was　used　to　sensitively　monitor　the　pressure　variations　in　this　system.　Thus,　the　concentration　of　the　target　could　be　quantitatively　determined　by　the　pressure　response.　Under　optimal　conditions,　the　pressure-based　immunosensor　showed　good　sensing　performance　for　CEA　in　the　dynamic　working　range　from　0.2　to　60　ng/mL　with　a　detection　limit　of　0.13　ng/mL.　The　reproducibility,　specificity,　and　accuracy　compared　with　commercial　enzyme-linked　immunosorbent　assay　(ELISA)　kit　were　also　acceptable.　Therefore,　this　work　provides　a　promising　approach　for　developing　portable　and　sensitive　POC　testing　in　the　future.　©　2020　American　Chemical　Society.