TRIGGERING SEQUENCE

A therapeutic substance delivery device includes a fluid path having a reservoir needle, a body needle, a body needle injection mechanism, and a pumping assembly (a) configured to pump the substance from the reservoir to the subject, (b) shaped to define a pump chamber, and (c) including a plunger disposed within the pump chamber. The plunger moves back and forth through a plurality of discrete motion phases. A first motion phase of the plunger actuates a first operation from a group of operations including (a) driving the reservoir needle to penetrate the reservoir, (b) advancing the body needle into the body of the subject, (c) withdrawing the substance from the reservoir, (d) pumping the substance into the subject, and (e) retracting the body needle. A second motion phase of the plunger actuates a second operation from the group of operations. Other applications are also described.