Needle bending is a significant cause of error in biopsies, leading to lesion missampling and consequent cancer misdiagnosis. This paper presents the design of a new mechanism that detects the needle bending as soon as it occurs and immediately reduces the insertion force. Importantly, this is achieved without employing external sensors or electromechanical actuators. Experiments on a silicone-rubber phantom indicate that the proposed device can help to avoid deep insertions with bent needles, thus potentially reducing the associated risks and improving patient safety in biopsies and percutaneous interventions.