Body　fluid　pH　is　an　important　indicator　of　the　health　of　the　human　body,　and　potentiometric　sensors　can　be　used　to　determine　the　health　of　people　by　measuring　body　fluid　pH.　However,　most　of　these　sensors　face　the　limitations　of　low　sensitivity　and　high　cost.　In　this　paper,　we　propose　three　pH　sensor　schemes　based　on　the　CMOS-ISFET　process　and　complete　the　simulation　of　these　three　schemes.　They　are　available　in　different　precision　CMOS　processes　0.5μmCMOS,　0.6μmCMOS,　and　65nm　CMOS,　while　their　sensitivities　are　11　mV/pH,　5SmV/pH,　and　43　mV/pH　respectively.　Each　of　these　three　schemes　has　its　advantages　and　disadvantages,　giving　their　respective　options　in　different　processes,　different　scaling　relationships,　and　different　precision,　providing　a　diversity　of　options　in　future　multifunctional　chips.　　©　2023　IEEE.