Described examples include a sensor device having at least one conductive elongated first pillar positioned on a central pad of a first conductor layer over a semiconductor substrate, the first pillar extending in a first direction normal to a plane of a surface of the first conductor layer. Conductive elongated second pillars are positioned in normal orientation on a second conductor layer over the semiconductor substrate, the conductive elongated second pillars at locations coincident to via openings in the first conductor layer. The second conductor layer is parallel to and spaced from the first conductor layer by at least an insulator layer, the conductive elongated second pillars extending in the first direction through a respective one of the via openings. The at least one conductive elongated first pillar is spaced from surrounding conductive elongated second pillars by gaps.