Injection device with a capacitive proximity sensor

Injection device for injecting medication to a patient, comprising a surface having a through hole for passage of a needle and a capacitive proximity sensor for detecting proximity or contact of human skin to/with said surface, wherein the capacitive proximity sensor comprises a first electrode, a second electrode defining a capacitance with the first electrode and means for detecting a change in said capacitance due to the proximity of human skin to the sensor, and wherein one side of the first electrode is adjacent to the through hole and has a concave shape that follows part of the contour of the through hole.