The present invention provides a reusable spring driven autoinjector. The drive mechanism of the autoinjector of the present invention includes one or more drive springs formed of a shape memory alloy. Therefore, by alternating the shape memory alloy forming the one or more drive springs between austenite phase before an injection and a martensite phase after injection, the reusable autoinjector of the present invention is capable of providing an injection force that is higher than the compressive force required to cock the drive mechanism in preparation for a subsequent injection operation.

A medical device includes a sensor that is configured to measure a property of an outer layer of an anatomical body surface. The sensor includes a source probe configured to stimulate a local surface of the outer layer of an anatomical body surface. The sensor also includes a detector configured to measure a response of the outer layer resulting from the source probe stimulation. A controller coupled to the source probe and the sensor drives the source probe using a tailored stochastic sequence and determines the property of the outer layer using the measured response received from the detector. The sensor can be used with medical devices, such as drug delivery devices including microneedle transport devices and needleless injection devices.

An injector includes a housing having a chamber for holding a liquid formulation of an active principle to be injected into a biological body and an output port in fluid communication with the chamber through which the liquid formulation is injected. A piston is positioned within the housing, and includes an end portion with substantially the same shape as the chamber. A magnetic force draws the piston and housing together to expel the liquid formulation out of the chamber through the output port.