A system (110; 1510; 1610; 1710; 1810) for measuring injection of a liquid medicine, comprising: a syringe body having proximal and distal ends (120, 122), a syringe interior, and a syringe flange at the proximal end thereof; a stopper member disposed in the syringe interior; a plunger member coupled to the stopper member and configured to be manipulated to insert the stopper member distally in the syringe interior relative to the syringe body; a needle coupled to the syringe body at the distal end thereof; and a sensor flange (150; 1150; 1550; 1650; 1750; 1850) removably and slidably attached in a radial direction to the syringe body, the sensor flange (150; 1150; 1550; 1550; 1650; 1750; 1850) having a flat shape that is a flange and comprising: a sensor (152, 160; 1152; 1588; 1692; 1798; 1898) to measure an injection characteristic; a processor to analyze the injection characteristic to determine an occurrence of an injection of a dose of the liquid medicine; and a mounting sensor (158; 1158) to detect when the sensor flange (150; 1150) is removably coupled to the syringe body, wherein the mounting sensor (158, 1158) comprises a mechanical switch, characterized in that the sensor flange (150; 1150; 1550; 1650; 1750; 1850) is configured to deliver an alarm once the injection of the dose of the liquid medicine has been completed to prevent the sensor flange (150; 1150; 1550; 1650; 1750; 1850) from being disposed of prematurely, wherein the alarm is silenced once the mounting sensor (158; 1158) indicates the sensor flange has been removed from the syringe body. a syringe body having proximal and distal ends (120, 122), a syringe interior, and a syringe flange at the proximal end thereof; a stopper member disposed in the syringe interior; a plunger member coupled to the stopper member and configured to be manipulated to insert the stopper member distally in the syringe interior relative to the syringe body; a needle coupled to the syringe body at the distal end thereof; and a sensor flange (150; 1150; 1550; 1650; 1750; 1850) removably and slidably attached in a radial direction to the syringe body, the sensor flange (150; 1150; 1550; 1550; 1650; 1750; 1850) having a flat shape that is a flange and comprising: a sensor (152, 160; 1152; 1588; 1692; 1798; 1898) to measure an injection characteristic; a processor to analyze the injection characteristic to determine an occurrence of an injection of a dose of the liquid medicine; and a mounting sensor (158; 1158) to detect when the sensor flange (150; 1150) is removably coupled to the syringe body, wherein the mounting sensor (158, 1158) comprises a mechanical switch, a sensor (152, 160; 1152; 1588; 1692; 1798; 1898) to measure an injection characteristic; a processor to analyze the injection characteristic to determine an occurrence of an injection of a dose of the liquid medicine; and a mounting sensor (158; 1158) to detect when the sensor flange (150; 1150) is removably coupled to the syringe body, wherein the mounting sensor (158, 1158) comprises a mechanical switch, characterized in that the sensor flange (150; 1150; 1550; 1650; 1750; 1850) is configured to deliver an alarm once the injection of the dose of the liquid medicine has been completed to prevent the sensor flange (150; 1150; 1550; 1650; 1750; 1850) from being disposed of prematurely, wherein the alarm is silenced once the mounting sensor (158; 1158) indicates the sensor flange has been removed from the syringe body.