Rolling bearings include a plurality of rolling bodies which during operation roll on raceways. In order to reduce friction during rolling, it is customary to supply the rolling bearings with a lubricant. However, the quality of the lubricant can deteriorate during operation due to long-term stress, aging, or thermal influences, or get lost in gaps etc. The objective addressed by the invention is that of providing a sensor device, which can be operated in a functionally reliable manner. This objective is achieved by a sensor device for monitoring the state of a lubricant in a lubricant chamber, including a transmitter platform, wherein on the transmitter platform, a plurality of diode devices are arranged, having a measurement window device, wherein the measurement window device is arranged between a measuring chamber and the lubricant chamber, having a receiving device, wherein at least one of the diode devices comprises a die and a plastic dome. The plastic dome and the die are connected by way of a contact surface, wherein the contact surface is arranged on an upper side of the die.