This paper presents a novel micromachined high-responsivity thermopile sensor, fully compatible with standard CMOS-SOI (Silicon-On-Insulator) processes. The proposed thermopile features a versatile mosaic structure, based on 128 60 um x 60 um pixels connected in series and/or in parallel. Two versions of the proposed thermopile sensor, featuring a different number of equivalent pixels, are presented and fully characterized. The most performing of the two features 2.9x10^4 V/W-responsivity, outperforming other state-of-the-art thermopile sensors. The application of the most performing thermopile as proximity and motion detector was also verified through measurements.