The miniaturizable sensor comprises an insulating substrate (10) supporting first measurement electrode (24) and comprising a flexible measurement arm (18) of conductive or semiconductor material, one end of which is secured to the substrate (10) and the other end of which constitutes a second electrode facing the first electrode. The first end of the measurement arm is secured to the substrate via a beam (16) having a bending modulus at least ten times greater than that of the measurement arm (18) and substantially parallel to the measurement arm and via a foot (14) rigidly secured to the substrate (10) and situated between the two ends of the measurement arm, the connections of the beam (16) to the measurement arm (18) and to the foot (14) being of the fixed-end type.