In　this　paper,　we　introduced　a　signal-on　electrochemical　sensor　based　on　target-induced　split　aptamer　fragments　conjunction.　To　construct　the　aptasensor,　the　sequence　of　the　15-base　anti-thrombin　DNA　aptamer　was　split　into　two　fragments.　one　of　which　was　attached　to　a　gold　electrode　via　thiol　self-assembled　monolayer　chemistry　and　the　second　of　which　was　modified　with　the　redox　moiety　ferrocene.　Thrombin-induced　association　of　the　two　fragments　thus　increased　the　concentration　of　ferrocene　at　the　electrode　surface,　which　could　be　readily　monitored　via　voltammetry.　The　sensitivity　of　the　proposed　electrochemical　aptasensor　was　investigated　by　differential　pulse　voltammogram.　The　results　indicated　that,　in　pH　7.1　Tris-HCl　buffer　solution,　the　peak　current　was　linear　with　the　concentration　of　thrombin　in　the　range　of　0.8-15　nM　with　a　detection　limit　of　0.2　nM.　The　proposed　aptasensor　has　the　advantages　of　higher　sensitivity　and　lower　background　current.　Given　the　simplicity　in　design　of　the　proposed　electrochemical　aptasensor,　it　is　fairly　easy　to　generalize　this　strategy　to　detect　a　spectrum　of　targets　by　splitting　the　aptamers　into　two　suitable　segments.　Furthermore,　this　design　could　be　also　used　to　construct　novel　optical　aptasensors.　(C)　2009　Elsevier　B.V.　All　rights　reserved.