the present invention discloses a biological detection device and a detecting method . the biological detection device comprises a substrate , an electric field unit , a liquid crystal / polymer composite film , a power supply , a processing unit , and an image sensor . because of the electrically tunable orientations of the liquid crystal director anchored among the polymer grains , the wettability of the lcpcf changes with an applied electric field . as a result , we can manipulate a blood droplet on the lcpcf by a wettability gradient owing to the distribution of lc directors on the lcpcf . the motion states of the blood droplet can be related to the various qualities of the blood , and finally determines the health of the test sample . the change of contact angle of blood on lcpcf and the blood droplet motion on lcpcf indicate the concentration of tg and the concentration of hdl .