an oximetry sensor; and

an adapter;

wherein the oximetry sensor comprises a detection end and an output end; the detection end comprises a photodetector and a plurality of light emitting elements capable of independently emitting light beams of different peak wavelengths; the light emitting elements are connected in series; the output end has a plurality of output ports; two adjacent output ports are electrically connected to two sides of the corresponding light emitting element, respectively;

the adapter has a first adapter end and a second adapter end; the first adapter end is configured to adapt to an input end of a target monitor; the second adapter end is configured to adapt to the output end of the oximetry sensor; a plurality of first wires are provided between the second adapter end and the first adapter end; the first adapter end is electrically connected with the input end of the target monitor to allow one end of each first wire to be electrically connected with a corresponding input port at the input end of the target monitor; the output ports are greater than the first wires in number; when the second adapter end is connected to the output end, the other end of each first wire is electrically connected with the corresponding output port to form a closed circuit, so as to enable the light emitting element between the two adjacent output ports in the closed circuit to emit light, and the emitted light is received by the photodetector to generate a detection signal associated with a blood oxygen saturation of a patient which is displayed on the target monitor.