Springs are a common method of achieving an "over centre" action. A spring attached to a simple two position ratchet-type mechanism can create a button or plunger that is clicked or toggled between two mechanical states. Many ballpoint and rollerball retractable pens employ this type of bistable mechanism.

Which is a bistable device?

A bistable device is a device that can be either in one of the two possible states such as on or off, pulse or no pulse, 0 or 1. Transistors, flip-flop and organic bistable devices are examples of bistable device.

What is bistable expression?

Bistable regulation results in the same gene being expressed in some cells and silenced in others, an outcome that promotes cellular differentiation. ... If repressors bind both upstream and downstream of the coding sequence, the response is bistable.