Automatic fluid product injection device

An automatic fluid injection device comprising:

• a body fastened to a support for coming into contact with an injection zone, said body containing one or more fluid reservoirs each containing an injection piston;
• a needle assembly including an injection needle for penetrating into the injection zone;
• and an injection mechanism;
• said needle assembly including an injection needle for penetrating into the injection zone and an insertion actuator made of a shape memory alloy, wherein the needle assembly comprises a retraction ring;
• a needle support;
• an insertion ring;
• a retraction spring;
• an actuator ring;
• and an insertion spring;
• the insertion spring and the retraction spring being retained, at rest, in a compressed state by respective locking means, activation of the insertion actuator by heating in order to reach about 50% of the available contraction causing the actuator ring to move relative to the insertion ring with one end of the insertion actuator fastened to the insertion ring, thereby causing the needle support to be released and enabling the insertion spring to extend, which causes the needle support and the injection needle to penetrate into the injection zone, and activation of the actuator by heating in order to reach 100% of the available contraction causing the insertion actuator ring to move relative to the retraction ring, thereby causing the insertion ring and the assembly formed of the needle support and of the injection needle to be released, such that the retraction spring retracts the injection needle out from the injection zone.