'Nikola's silicone skin is less elastic than real human skin and cannot form wrinkles very well,' the researchers explained. They found that the participants could recognise the six emotions – albeit with varying accuracies. To put these facial expressions to the test, the researchers showed Nikola to a group of participants while it displayed its six facial expressions. Using a coding system called the Facial Action Coding System (FACS), the team can control subtle movements such as 'cheek raises' and 'lip puckers', allowing them to convey six emotions. These actuators are controlled by air pressure, which the team says results in 'silent and smooth' movements.
Nikola's face includes 29 pneumatic actuators that control the movement of artificial muscles, with a further six actuators used to control head and eyeball movements.