Above: The third layer is an array of tiny inkjet piezoelectric nozzles that squirts air. The longer each inkjet nozzle stays open, the more air it lets into the pocket, so the shape heights have very high resolution.
The technology for piezo inkjet nozzles is well-established and needs no modification: a voltage causes the piezoelectric material to change shape.
Above: The final layer is an air pump that is shared by all the inkjet nozzles. The pump has a membrane that moves air in and out to make pressure and vacuum. The inkjet nozzles use this pressure and vacuum to fill and empty the pockets. The quantities of air needed are tiny. The fill rate needn't be very fast - the image only updates when the user lifts their finger.
