Fluid delivery device with sensor

An apparatus, comprising:

• a reservoir configured to hold a liquid drug;
• a fluid path component configured to couple the reservoir to a user;
• a plunger configured to expel the liquid drug from the reservoir for delivery to the user;
• an absolute pressure sensor configured to detect atmospheric pressure and relative pressure;
• and
• a monitoring component including circuitry configured to:
• receive a first signal from a pressure sensor indicative of a first pressure at a start of a delivery operation for a liquid;
• determine the first pressure at the start of the delivery operation for the liquid drug based on the received first signal;
• receive a second signal from the pressure sensor indicative of a second pressure at an end of the delivery operation for the liquid;
• determine the second pressure at the end of the delivery operation for the liquid drug based on the second signal;
• determine a fluid capacitance value of a fluid path used for the delivery operation of the liquid drug;
• determine an intended liquid drug delivery amount;
• determine a delivery error amount of the liquid drug based on the first and second pressures, the fluid capacitance value, and the intended liquid drug delivery amount;
• and
• in response to the determined delivery error amount, actuate an alarm actuator by outputting an alert-alarm signal, the alarm actuator configured to activate an alarm.