The　present　study　aims　to　provide　an　overall　analysis　about　nanofluids　flowing　through　microchannel　heat　sinks.　Al2O3　and　TiO2　nanofluids　based　on　deionized　water　with　particle　volume　fractions　of　0%,　0.1%,　0.5%,　1.0%　were　prepared　by　the　two-step　dispersion　method.　Nonionic　surfactant　polyvinylpyrrolidone　(PVP)　was　added　into　the　nanofluids　to　avoid　particle　aggregation　and　enhance　stability.　An　ImageIR　3350　was　used　to　get　the　temperature　distribution　on　the　substrate　of　microchannel　heat　sinks.　The　results　reveal　that　the　thermal　conductivity　and　dynamic　viscosity　of　Al2O3　and　TiO2　nanofluids　are　both　improved　with　the　increase　of　particle　volume　fraction.　Compared　with　a　rectangular　microchannel　heat　sink,　the　performance　of　heat　transfer　in　fan-shaped　microchannel　heat　sink　is　more　strengthened　using　Al2O3　nanofluids.　The　thermal　motion　of　nanoparticles　could　promote　the　interruption　of　laminar　flow　and　intensify　the　heat　transfer　between　fluids　and　channel　walls.　The　cyclical　change　with　a　fixed　period　on　equivalent　diameter　could　also　help　destroy　the　boundary　layers.　(C)　2016　Elsevier　Ltd.　All　rights　reserved.