Among others, the present invention provides apparatus for detecting circulating tumor cells, comprising a system delivery biological subject and a probing and detecting device, wherein the probing and detecting device includes a first micro-device and a first substrate supporting the first micro-device, the first micro-device contacts a biologic material to be detected and is capable of measuring at the microscopic level an electrical, magnetic, electromagnetic, thermal, optical, acoustical, biological, chemical, electro-mechanical, electro-chemical, electro-optical, electro-thermal, electro-chemical-mechanical, bio-chemical, bio-mechanical, bio-optical, bio-thermal, bio-physical, bio-electro-mechanical, bio-electro-chemical, bio-electro-optical, bio-electro-thermal, bio-mechanical-optical, bio-mechanical thermal, bio-thermal-optical, bio-electro-chemical-optical, bio-electro-mechanical-optical, bio-electro-thermal-optical, bio-electro-chemical-mechanical, physical or mechanical property, or a combination thereof, of the biologic subject.