Semiconductor-based　photoelectrochemical　(PEC)　test　protocols　offer　a　viable　solution　for　developing　efficient　individual　health　monitoring　by　converting　light　and　chemical　energy　into　electrical　signals.　However,　slow　reaction　kinetics　and　electron-hole　complexation　at　the　interface　limit　their　practical　application.　Here,　we　reported　a　triple-engineered　CdS　nanohierarchical　structures　(CdS　NHs)　modification　scheme　including　morphology,　defective　states,　and　heterogeneous　structure　to　achieve　precise　monitoring　of　the　neurotransmitter　dopamine　(DA)　in　plasma　and　noninvasive　body　fluids.　By　precisely　manipulating　the　Cd-S　precursor,　we　achieved　precise　control　over　ternary　CdS　NHs　and　obtained　well-defined　layered　self-assembled　CdS　NHs　through　a　surface　carbon　treatment.　The　integration　of　defect　states　and　the　thin　carbon　layer　effectively　established　carrier　directional　transfer　pathways,　thereby　enhancing　interface　reaction　sites　and　improving　the　conversion　efficiency.　The　CdS　NHs　microelectrode　fabricated　demonstrated　a　remarkable　negative　response　toward　DA,　thereby　enabling　the　development　of　a　miniature　self-powered　PEC　device　for　precise　quantification　in　human　saliva.　Additionally,　the　utilization　of　density　functional　theory　calculations　elucidated　the　structural　characteristics　of　DA　and　the　defect　state　of　CdS,　thus　establishing　crucial　theoretical　groundwork　for　optimizing　the　polymerization　process　of　DA.　The　present　study　offers　a　potential　engineering　approach　for　developing　high　energy　conversion　efficiency　PEC　semiconductors　as　well　as　proposing　a　novel　concept　for　designing　sensitive　testing　strategies.　©　2024　American　Chemical　Society.