A method of joining a device to a joining location (2.1) of an object , the method comprising the steps of: providing the device comprising a first solid portion (1.1) containing a first thermoplastic polymer and a susceptor additive being at least one of electrically conducting and magnetic and being present in the first portion (1.1) in an amount sufficient for rendering the first portion (1.1) capable of being heated by electromagnetic induction, positioning the device relative to the joining location (2.1), positioning the device into an alternating electromagnetic field suitable for heating the first portion (1.1) by electromagnetic induction for a time sufficient for raising the temperature of the first portion (1.1), applying ultrasonic vibration energy to the device or to the object and simultaneously applying a compression force to the device for a time sufficient for liquefying or plasticizing at least part of the first portion and for achieving at least one of bringing the liquefied or plasticized first portion into contact with at least a surface of the joining location (2.1) and deforming the device , characterized in that the time for which the device is positioned in the alternating electromagnetic field suitable for heating the first portion (1.1) by electromagnetic induction is not sufficient for liquefying or plasticizing the first polymer and in that the method comprises the step of stopping the application of the alternating electromagnetic field and the application of the ultrasonic vibration while maintaining the compression force for a time sufficient for achieving, on re-solidification of the liquefied or plasticized first portion (1.1), a connection between the device and the joining location (2.1). providing the device comprising a first solid portion (1.1) containing a first thermoplastic polymer and a susceptor additive being at least one of electrically conducting and magnetic and being present in the first portion (1.1) in an amount sufficient for rendering the first portion (1.1) capable of being heated by electromagnetic induction, positioning the device relative to the joining location (2.1), positioning the device into an alternating electromagnetic field suitable for heating the first portion (1.1) by electromagnetic induction for a time sufficient for raising the temperature of the first portion (1.1), applying ultrasonic vibration energy to the device or to the object and simultaneously applying a compression force to the device for a time sufficient for liquefying or plasticizing at least part of the first portion and for achieving at least one of bringing the liquefied or plasticized first portion into contact with at least a surface of the joining location (2.1) and deforming the device , characterized in that the time for which the device is positioned in the alternating electromagnetic field suitable for heating the first portion (1.1) by electromagnetic induction is not sufficient for liquefying or plasticizing the first polymer and in that the method comprises the step of stopping the application of the alternating electromagnetic field and the application of the ultrasonic vibration while maintaining the compression force for a time sufficient for achieving, on re-solidification of the liquefied or plasticized first portion (1.1), a connection between the device and the joining location (2.1). <EOS>