The　DNA　intensity　modified　on　the　surface　of　the　inner　wall　of　microchannel　can　regulate　the　resistance　of　the　microchannel　and　which　can　be　used　to　design　biosensors　for　diverse　targets.　In　this　study,　a　portable　biosensor　based　on　the　regulation　of　the　charge　density　in　microchannel　using　multimeter　as　redout　had　been　designed　for　disease　related　DNA　sequence　detection　(p53　gene　had　been　chosen　as　model　target).　The　inner　wall　of　microchannel　was　functionalized　with　ssDNA　firstly,　where　target　p53　activated　Cas12a　via　crRNA,　whose　cleavage　activity　altered　the　inner　surface　charge　density,　thereby　changing　resistance　of　the　channel,　which　can　be　detected　by　a　simple　multimeter　easily.　Key　operational　parameters　such　as　KCl　concentration,　CRISPR/Cas12a　cleavage　time,　the　concentration　of　modified　ssDNA,　and　the　amounts　of　Cas12a/crRNA　complex　were　systematically　optimized　to　enhance　detection　performance.　Under　optimized　conditions,　the　changing　of　the　resistance　of　the　channel　exhibited　a　linear　relationship　with　the　logarithm　of　p53　gene　concentration　ranging　from　50　fM　to　50　pM,　achieving　a　detection　limit　of　15　fM　(S/N　=　3).　The　sensor　demonstrated　high　sensitivity,　specificity,　and　operational　convenience,　offering　a　promising　point-of-care　testing　for　disease　related　DNA　detection.　©　2025　Elsevier　B.V.