In a general aspect, a syringe terminates the dispensing of a fluid based on a force applied to a plunger member of the syringe. In some aspects, a plunger member of a syringe includes a top portion, a bottom portion, and a contact portion. The top and bottom portions are in contact with the contact portion, and the bottom portion has a length greater than or equal to a length of the top portion. The contact portion permits the top portion to move independent of the bottom portion in response to a stress in the contact portion exceeding a critical stress. The stress in the contact portion is based on a first force applied to the top portion and a second force opposite the first force applied to the bottom portion.
