Continuous-flow　microfluidic　biochips　have　attracted　high　research　interest　over　the　past　years.　Inside　such　a　chip,　fluid　samples　of　milliliter　volumes　are　efficiently　transported　between　devices　(e.g.,　mixers,　heaters,　etc.)　to　automatically　perform　various　laboratory　procedures　in　biology　and　biochemistry.　Each　transportation　task,　however,　requires　an　exclusive　flow　path　composed　of　multiple　contiguous　microchannels　during　its　execution　period.　Excess/waste　fluids,　in　the　meantime,　should　be　discarded　by　independent　flow　paths　connected　to　waste　ports.　All　these　paths　are　etched　in　a　very　tiny　chip　area　using　multilayer　soft　lithography　and　driven　by　flow　ports　connecting　with　external　pressure　sources,　forming　a　highly　integrated　chip　architecture　that　determines　the　final　performance　of　biochips.　In　this　article,　we　propose　a　new　and　practical　design　flow　called　PathDriver+　(PD+)　for　the　architecture　design　of　microfluidic　biochips,　integrating　the　actual　fluid　manipulations　into　both　high-level　synthesis　and　physical　design,　which　has　never　been　considered　in　prior　work.　With　this　design　flow,　highly　efficient　chip　architectures　with　a　flow-path　network　that　enables　the　actual　fluid　transportation　and　removal　can　be　constructed　automatically.　Meanwhile,　fluid　volume　management　between　devices　and　flow-path　minimization　are　realized　for　the　first　time,　thus,　ensuring　the　correctness　of　assay　outcomes　while　reducing　the　complexity　of　chip　architectures.　Additionally,　diagonal　channel　routing　is　implemented　to　fundamentally　improve　the　chip　performance.　The　tradeoff　between　the　numbers　of　channel　intersections　and　fluidic　ports　is　evaluated　to　further　reduce　the　fabrication　cost　of　biochips.　The　experimental　results　on　multiple　benchmarks　confirm　that　the　proposed　design　flow　leads　to　high　assay　execution　efficiency　and　low　overall　chip　cost.