Electromagnetic waves can cause electronic devices to malfunction unintentionally. Implantable medical devices must be specially designed to be immune to radio frequency interference. Measuring the electric field around an IMD is one approach to determine whether it might malfunction. This paper presents an experimental set-up that emulates the conditions of a medical device implanted inside a human body. Using an electric field probe for liquids, the field around the IMDs is measured. As result, the heat maps around the IMDs are shown, which allows us to infer that at frequencies of 850 MHz there is no reason to consider that the device may have malfunctioned.