A skin sensing system for a drug delivery device comprising: a control unit; and a skin sensor comprising one or more electrodes (705, 710), control units (715, 720) and storage units (725, 730), respectively; the skin sensor being configured to: (a.) store a threshold value associated with skin sensing; (b.) store a range of electrode signal values that are calculated as percentages of the threshold value; (c,) receive one or more sensed signal values from the one or more electrodes (705, 710); (d.) compare the one or more sensed signal values with the threshold value; and (e.) based on the comparison, transmit a resultant signal to the control unit wherein, in a detection mode for detecting establishment of a skin contact prior to initiation of a drug delivery sequence, the control unit is configured to use the resultant signal to determine whether a skin surface of a user is substantially proximate to the skin sensor upon receiving the resultant signal, and, in a monitoring mode for continuously determining whether there is any change to the established skin contact while the drug is administered, the control unit is further configured to monitor the skin sensing during a drug delivery process, the control unit being configured to determine whether the skin sensor is substantially proximate to the skin surface based on the resultant signal from the skin sensor indicating whether the one or more sensed signal values are within a fluctuation window of electrode signal values, the fluctuation window including the range of electrode signal values stored in the skin sensor. a control unit; and a skin sensor comprising one or more electrodes (705, 710), control units (715, 720) and storage units (725, 730), respectively; the skin sensor being configured to: (a.) store a threshold value associated with skin sensing; (b.) store a range of electrode signal values that are calculated as percentages of the threshold value; (c,) receive one or more sensed signal values from the one or more electrodes (705, 710); (d.) compare the one or more sensed signal values with the threshold value; and (e.) based on the comparison, transmit a resultant signal to the control unit wherein, in a detection mode for detecting establishment of a skin contact prior to initiation of a drug delivery sequence, the control unit is configured to use the resultant signal to determine whether a skin surface of a user is substantially proximate to the skin sensor upon receiving the resultant signal, and, in a monitoring mode for continuously determining whether there is any change to the established skin contact while the drug is administered, the control unit is further configured to monitor the skin sensing during a drug delivery process, the control unit being configured to determine whether the skin sensor is substantially proximate to the skin surface based on the resultant signal from the skin sensor indicating whether the one or more sensed signal values are within a fluctuation window of electrode signal values, the fluctuation window including the range of electrode signal values stored in the skin sensor. (a.) store a threshold value associated with skin sensing; (b.) store a range of electrode signal values that are calculated as percentages of the threshold value; (c,) receive one or more sensed signal values from the one or more electrodes (705, 710); (d.) compare the one or more sensed signal values with the threshold value; and (e.) based on the comparison, transmit a resultant signal to the control unit wherein,