A sensor device, comprising a self-sufficient sensor base unit for determining process variables in an industrial environment and at least one first expansion module, which can be attached to the sensor base unit, and a further expansion module; wherein the self-sufficient sensor base unit comprises: a first wireless communication unit, configured both to transmit signals to the first expansion module and/or receive signals from the first expansion module and to transmit signals to the further expansion module (702, 703) and/or to receive signals from the further expansion module and/or a first wireless power transmission unit, configured both to transmit power to the first expansion module and/or to receive power from the first expansion module and to transmit power to the further expansion module (702, 703) and/or to receive power from the further expansion module (702, 703); a first housing with a first receiving device, configured to receive the first expansion module, wherein the first housing completely encloses the sensor base unit; and wherein the first expansion module comprises: a second wireless communication unit configured to transmit signals to the sensor base unit and/or receive signals from the sensor base unit; and a second housing having a second receiving device configured to match the first receiving device so that the first expansion module can be received by the sensor base unit, and a third receiving device for receiving the further expansion module, wherein the second housing completely encloses the first expansion module; and whereby the further expansion module comprises: a third wireless communication unit configured to transmit signals to the sensor base unit and/or receive signals from the sensor base unit; and a third housing with a further receiving device, which is designed to match the third receiving device, so that the further expansion module can be received by the first expansion module, wherein the third housing completely encloses the further expansion module; and wherein the first expansion module and the further expansion module have different assemblies, components, interfaces and/or functionalities. a first wireless communication unit, configured both to transmit signals to the first expansion module and/or receive signals from the first expansion module and to transmit signals to the further expansion module (702, 703) and/or to receive signals from the further expansion module and/or a first wireless power transmission unit, configured both to transmit power to the first expansion module and/or to receive power from the first expansion module and to transmit power to the further expansion module (702, 703) and/or to receive power from the further expansion module (702, 703); a first housing with a first receiving device, configured to receive the first expansion module, wherein the first housing completely encloses the sensor base unit; and wherein the first expansion module comprises: a second wireless communication unit configured to transmit signals to the sensor base unit and/or receive signals from the sensor base unit; and a second housing having a second receiving device configured to match the first receiving device so that the first expansion module can be received by the sensor base unit, and a third receiving device for receiving the further expansion module, wherein the second housing completely encloses the first expansion module; and whereby the further expansion module comprises: a third wireless communication unit configured to transmit signals to the sensor base unit and/or receive signals from the sensor base unit; and a third housing with a further receiving device, which is designed to match the third receiving device, so that the further expansion module can be received by the first expansion module, wherein the third housing completely encloses the further expansion module; and wherein the first expansion module and the further expansion module have different assemblies, components, interfaces and/or functionalities. a second wireless communication unit configured to transmit signals to the sensor base unit and/or receive signals from the sensor base unit; and a second housing having a second receiving device configured to match the first receiving device so that the first expansion module can be received by the sensor base unit, and a third receiving device for receiving the further expansion module, wherein the second housing completely encloses the first expansion module; and whereby the further expansion module comprises: a third wireless communication unit configured to transmit signals to the sensor base unit and/or receive signals from the sensor base unit; and a third housing with a further receiving device, which is designed to match the third receiving device, so that the further expansion module can be received by the first expansion module, wherein the third housing completely encloses the further expansion module; and wherein the first expansion module and the further expansion module have different assemblies, components, interfaces and/or functionalities. a third wireless communication unit configured to transmit signals to the sensor base unit and/or receive signals from the sensor base unit; and a third housing with a further receiving device, which is designed to match the third receiving device, so that the further expansion module can be received by the first expansion module, wherein the third housing completely encloses the further expansion module; and wherein the first expansion module and the further expansion module have different assemblies, components, interfaces and/or functionalities.