Contact lenses that can monitor the wearer’s health and correct eyesight use embedded electronics. These, and other curved devices such as solar cells and electronics, could be manufactured using a new method called conformal additive stamp (CAS) printing.
Electronic devices are typically manufactured in planar layouts but many emerging applications require three-dimensional curvy structures. Fabrication of such structures has proved challenging due to the lack of an effective manufacturing technology. Existing manufacturing technologies, including micro-fabrication, don’t work for curved, three-dimensional electronics because they are inherently designed to produce two-dimensional, flat electronic devices. These devices are small — ranging in size from millimeters to centimeters — with accuracy within a few microns.
With CAS printing, an elastomeric (stretchy) balloon is inflated and coated with a sticky substance. It is then used as a stamping medium, pushing down on prefabricated electronic devices to pick up the electronics and then print them onto various curvy surfaces. The method was used to create a variety of curvy devices including silicon pellets, photodetector arrays, small antennas, hemispherical solar cells, and smart contact lenses.
The work was performed using a manual version of the CAS printer, although the researchers also designed an automated version.