Nice one! This device wasn't just a concept. It was actually used by Beverly Crusher in TNG season 7 episode 22 "Bloodlines" when she took a blood sample of Picard's "son" to check his DNA. While holding the top part to his neck she pulled the bottom part away to fill the vial with blood... It is just a very short scene, felt like maybe 2-3 seconds. But the device was clearly visible.