This paper introduces a new sensor architecture for making interactive surfaces that are sensitive to human hand and finger gestures. This sensor recognizes multiple hand positions and shapes and calculates the distance between the hand and the surface by using capacitive sensing and a mesh-shaped antenna. In contrast to camera-based gesture recognitionsystems, all sensing elements can be integrated within the surface, and this method does not suffer from lightingand occlusion problems. This paper describes the sensor architecture, as well as two working prototype systems: a table-size system and a tablet-size system. It also describes several interaction techniques that would be difficult to perform without using this architecture. Keywords Interactive surfaces, gesture recognition, augmented tables, two-handed interfaces, touch-sensitive interfaces.