Abstract: An implantable bolus injector having a battery, an electronic control unit and an injector including a shape memory alloy spring, a standard low-tension spring, and a threaded top part with a stainless steel cannula. The electronic control unit is connected to the shape memory alloy spring via a direct connection to the lower part of the spring and via the low-tension spring that ensures a connection between the spring and the control unit during the expansion of the shape memory alloy spring.