| CPC A61M 5/31528 (2013.01) [A61M 5/31551 (2013.01); A61M 2005/3126 (2013.01); A61M 5/31568 (2013.01); A61M 5/31585 (2013.01); A61M 2205/3306 (2013.01); A61M 2205/3327 (2013.01)] | 27 Claims | 

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               1. A data collection device attachable to an injection device, the data collection device comprising: 
            a body attachable to a dial member of the injection device, the injection device comprising a trigger, the dial member, and an expelling mechanism, the injection device being configured such that during expelling of a medicament by the injection device, (a) a relative rotation occurs between the dial member and the trigger upon an advancement of the expelling mechanism of the injection device, and (b) the trigger is rotationally fixed relative to a housing of the injection device; 
                a sensor arrangement comprising a sensor and a sensed element, wherein the sensor is configured to detect a rotation of the body relative to the trigger during expelling of the medicament; 
                a processor arrangement configured to determine, based on the detected rotation, an amount of the medicament expelled by the injection device; and 
                a button attached to the body, wherein the button is axially displaceable relative to the body and wherein the button is freely rotatable relative to the body. 
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