Engineers in Japan are trying to get robots to imitate that particularly human expression — the smile.

They have created a face mask from human skin cells and attached it to robots with a novel technique that conceals the binding and is flexible enough to turn down into a grimace or up into a squishy smile.

The effect is something between Hannibal Lecter’s terrifying mask and the Claymation figure Gumby.

But scientists say the prototypes pave the way for more sophisticated robots, with an outward layer both elastic and durable enough to protect the machine while making it appear more human.

Beyond expressiveness, the “skin equivalent,” as the researchers call it, which is made from living skin cells in a lab, can scar and burn and also self-heal, according to a study published June 25 in the journal Cell Reports Physical Science.

“Human-like faces and expressions improve communication and empathy in human-robot interactions, making robots more effective in health care, service and companionship roles,” Shoji Takeuchi, a professor at the University of Tokyo and the study’s lead researcher, said in an email.

The research comes as robots are becoming more ubiquitous on factory floors.

There were 3.9 million industrial robots working on auto and electronics assembly lines and other work settings in 2022, according to the International Federation of Robotics.