A device for safely accessing
bone marrow and other tissues is disclosed. Such device comprises a needle
assembly, a sensor mechanism, and an
actuator configured to engage with the needle
assembly via the sensor mechanism to advance a tissue penetrable needle through a first tissue region and into a second tissue region. In one aspect, the first tissue region is a
bone cortex and the second tissue region is a
bone marrow cavity. The sensor mechanism is configured to disengage the
actuator from the needle once the needle has crossed the first tissue region (e.g.,
bone cortex) into the second tissue region (e.g.,
bone marrow cavity), thereby preventing the needle from advancing further into the second tissue region. In one aspect, the sensor mechanism is mechanical and comprises a pin
assembly comprising a spring-loaded pin that extends through the needle. The pin assembly is configured such that advancement of the distal tip of the spring-loaded pin past the distal tip of the needle causes the
actuator to disengage from the needle. The actuator is a rotatable actuator. A
catheter-based embodiment of the device can be inserted in body passageways to access tissue internally within the body.