An external infusion device (100; 301; 410) for infusing fluid into a person from a reservoir (305; 434); comprising: a housing (101; 318; 420) adapted to be carried on an exterior of the person; a drive mechanism (302 - 304, 306, 307; 432) contained in the housing and operatively coupled to the reservoir to deliver fluid from the reservoir into the person; a processor contained in the housing; an indicator (102; 416, 428, 430) operatively coupled to the processor and adapted to provide at least one of a visual indication, an audible indication, or a tactile indication to indicate information about the infusion device to the person; and an acceleration sensor coupled to the processor and adapted to provide an acceleration output signal as a function of acceleration forces acting on the housing, wherein the processor is adapted to control the infusion device in accordance with the acceleration output signal; characterized in that the acceleration sensor is an impact switch disposed within the housing (101; 318; 420), wherein the impact switch comprises: an electrical input and an electrical output; an electrically conductive seismic mass having an anchored end and a free end, the mass being electrically coupled to the electrical output, the mass being coupled to the housing (101; 318; 420) at the anchored end and adapted for resilient deflection in a first closing contact direction; and a first electrically conductive contact fixedly mounted adjacent to the mass, the first contact being electrically coupled to the electrical input, wherein the mass is adapted to deflect in the first closing contact direction from a first position to a second position, touch the first contact, and return from the second position to the first position such that a circuit between the electrical input and the electrical output is closed to provide the acceleration output signal when a first predetermined acceleration force acts on the housing. a housing (101; 318; 420) adapted to be carried on an exterior of the person; a drive mechanism (302 - 304, 306, 307; 432) contained in the housing and operatively coupled to the reservoir to deliver fluid from the reservoir into the person; a processor contained in the housing; an indicator (102; 416, 428, 430) operatively coupled to the processor and adapted to provide at least one of a visual indication, an audible indication, or a tactile indication to indicate information about the infusion device to the person; and an acceleration sensor coupled to the processor and adapted to provide an acceleration output signal as a function of acceleration forces acting on the housing, wherein the processor is adapted to control the infusion device in accordance with the acceleration output signal; an electrical input and an electrical output; an electrically conductive seismic mass having an anchored end and a free end, the mass being electrically coupled to the electrical output, the mass being coupled to the housing (101; 318; 420) at the anchored end and adapted for resilient deflection in a first closing contact direction; and a first electrically conductive contact fixedly mounted adjacent to the mass, the first contact being electrically coupled to the electrical input, wherein the mass is adapted to deflect in the first closing contact direction from a first position to a second position, touch the first contact, and return from the second position to the first position such that a circuit between the electrical input and the electrical output is closed to provide the acceleration output signal when a first predetermined acceleration force acts on the housing.