A　ratiometric　self-powered　photoelectrochemical　sensor　based　on　laser　direct　writing　technology　was　constructed　to　address　the　problem　that　the　conventional　single-signal　detection　mode　was　susceptible　to　the　influence　of　instrumentation　and　environmental　factors,　which　interfered　with　the　detection　results.　Laser-induced　CdS/TiO2/Graphene　was　prepared　as　dual　photoanodes　(PA1　and　PA2),　which　were　controlled　by　multiplexed　switches　to　form　a　photocatalytic　fuel　cell　with　Pt　cathode.　By　modifying　the　aptamer　of　aflatoxin　B1　(AFB1)　on　the　photoanode　surface,　the　target　was　specifically　captured　to　the　electrode　surface　to　form　a　biological　complex,　which　increased　the　steric　hindrance　and　affected　the　electron　transfer,　thus　reducing　the　output　signal　of　the　sensor.　Targets　with　different　concentrations　were　incubated　on　the　surface　of　PA1,　and　targets　with　fixed　concentrations　were　incubated　on　the　surface　of　PA2.　Under　the　control　of　the　multiplex　switch,　the　output　signals　of　the　two　photoanodes　were　recorded,　and　the　ratio　of　these　two　signals　was　used　as　the　basis　for　the　quantitative　detection　of　AFB1.　The　sensor　output　was　linearly　increasing　with　the　logarithm　of　AFB1　concentration　from　1.0　to　150 ng mL−1　and　the　detection　limit　was　0.0974 ng mL−1.　Additionally,　this　method　had　good　stability,　fast　response,　and　good　selectivity　to　real　samples,　providing　an　effective　method　for　food　safety　monitoring.　Graphical　Abstract:　(Figure　presented.)　©　The　Author(s),　under　exclusive　licence　to　Springer-Verlag　GmbH　Austria,　part　of　Springer　Nature　2024.