The diagnostic bed found in every Starfleet sickbay, fitted with sensors that read a patient's vital signs and show them on a display above the head.
Biobeds line the sickbay of Kirk's Enterprise in the Original Series, where a panel above each bed shows pulse, temperature, respiration and other readings with moving pointers and a steady heartbeat sound. Dr McCoy can judge a patient at a glance from the panel.
In The Next Generation, Deep Space Nine and Voyager the main surgical bed stands in the middle of sickbay under an overhead sensor cluster. A clamshell frame can be closed over the patient's body for surgery and to hold a sterile field, and the beds can also keep a patient in stasis.
Star Trek: Enterprise shows an earlier stage, with an imaging chamber into which the bed slides, while Strange New Worlds and the later series add holographic displays. The bed remains much the same across nine centuries of the setting.