Broadband infrared (IR) radiation detectors have been developed using miniature, inexpensive, mass produced microcantilevers capable of detecting temperature differences as small as 10(-6) K. Microcantilevers made out of semiconductor materials with dimensions of 50 to 200 mu m long, 10 to 30 mu m wide and 0.4 to 4 mu m thick, undergo bending when exposed to IR radiation and can be used either as uncooled photon or thermal detectors. Mounted on a probe 1 mm in diameter a number of microcantilevers can be accommodated in the working channel of existing endoscopes for in vivo proximity focus measurements inside the human body.