Electronics constructed in 3D curvilinear layouts have many applications; examples include smart contact lens with sensors integrated, wide field-of-view cameras from curved image sensor arrays, and spherical helix antennas with high radiation efficiency. However, it is very challenging to create 3D curvilinear electronics due to manufacturing technology gaps. This Faculty Early Career Development (CAREER) award supports fundamental research to provide needed knowledge to develop conformal stamp printing approach for 3D curvilinear electronics manufacturing. 3D curvilinear electronics made from conformal stamp printing can be used in healthcare, space, telecommunication, and energy industries. Therefore, outcomes from this research will benefit the U.S. economy and society. The award will also support educational and outreach activities, such as providing learning opportunities to high school students and their teachers, offering research experiences for undergraduate students (especially those from the underrepresented groups), and disseminating the latest science and engineering knowledge to the general public.
Conformal stamp printing involves employing an inflated elastomeric balloon (conformal stamp) to pick-up and print electronic components (inks) onto curvilinear surfaces to create 3D curvilinear electronics. The first research objective is to establish the relationship between the deformation and induced strain in the stamp. To achieve this objective, the stamp's material properties, including strain-stress relationship and modulus, will be characterized by tension tests of thin elastomeric sheets. Employing the measured properties, both analytical models based on strain energy in the stamp and finite element simulations of inflated stamp under deformation will be used to predict the quantitative relationship between the deformation and associated strain. The second objective is to quantify the effects of stamp peeling speed on the interfacial adhesion strength between stamp and inks. To achieve this objective, a model of adhesion strength related to peeling speed will be built based on the energy release rate when peeling to crack an interface between rigid silicon (ink) and viscoelastic elastomer (stamp). After being verified by experiments, the model will be used to predict the effects of peeling speed on interfacial adhesion strength. The third objective is to establish the relationship between the deformation of the stamp and the deformation, strain and pattern distortion of the inks. To achieve this objective, finite element simulations of the inks at deformed states during and after printing will be performed. After being verified by experiments, the simulations will be utilized to capture the inks' deformation, strain and pattern distortion with various deformation conditions of the stamp.
