Abstract: A flow conduit system (100,200a,200b) suitable for biochemical sensing, the flow conduit system (100,200a,200b) comprising, a first flow cell conduit (1) comprising one or more sensing areas for biochemical sensing; a first selector valve (4); a first inlet/outlet conduit (2) which fluidly connects the first flow cell conduit (1) to the first selector valve (4); a first injection conduit (6) having a first end and a second end; a second injection conduit (7) having a first end and a second end; a fluid injecting means (8) fluidly connected to the second ends of each of the first and second injection conduits (6, 7) so that the fluid injecting means can selectively inject fluids into the first and/or second injection conduits (6,7); wherein the first injection conduit (6) is fluidly connected, at its first end, to the first inlet/outlet conduit (2) by a valveless junction (9), and the second injection conduits (6) is fluidly connected, at its first end, to the first inlet/outlet conduit (2) by a valveless junc