Microfluidic chip integrated with amperometric detector array for in situ estimating oxygen consumption characteristics of single bovine embryos

The detection of oxygen consumption as an indicator of the bovine embryo activity has attracted much attention. A microfluidic chip with the built-in amperometric detector array was successfully constructed to transport, immobilize, and in situ measure a single bovine embryo for the evaluation of oxygen consumption characteristics. The microfluidic chip consisted of a poly(dimethylsiloxane) slab containing a size-limited transportation microchannel and a glass substrate with a 4-working-electrode amperometric detector array located on the bottom of a groove. A single embryo could be transported along the groove and be safely immobilized at the gate position of the microchannel due to the size limitation by using the flow rate of 10 μl/min. Subsequently, the oxygen consumption characteristics of the embryo were in situ measured with the amperometric detector array. The average value of oxygen concentration difference (ΔC) between the bulk solution and the Day-6 embryo surface based on the analysis of spherical diffusion theory was 2.80 ± 0.72 μM at room temperature. Moreover, the correlation coefficient of more than 0.92 indicates that the spherical diffusion theory could be suitable for depicting the oxygen consumption layer of an embryo at the morula stage in the microchannel. The success of the presently used microfluidic chip not only greatly simplifies the expensive instrument requirements such as scanning electrochemical microscope and stereo-positioning manipulator but also makes the transportation, immobilization, and detection of a single embryo feasible within a microchip.