Abstract
Most of the digital image capture devices use spherical lenses which have curved image plane that cannot match the flat CMOS image sensors. In this research, we try to design and fabricate a stretchable and curved image sensors array that can match the curved image planes formed by different spherical lenses. In this research, we realize the stretchable and curved image sensors array by embedding image sensor chips which were designed by our own into a stretchable PDMS film, and using the wire bonding technology to connect these chips into an array form. After the stretchable and curved image sensors array was fabricated, a series tests about stretchability and photoelectrical characteristic of this image sensors array were conducted. In the stretchability tests, the maximum uniaxial strain was 17.86 % which can be transferred into a dynamic curvature range from flat to a 14.84 mm radius of curvature for a 22mm-length film. In the photoelectrical characteristic tests, we use different lenses with suitable bases to perform the measurement and analyzing the result. The combination of lenses and bases are: 40 mm focal length with 40 mm radius of curvature, 60 mm focal length with 60 mm radius of curvature, and 120 mm focal length with 120 mm radius of curvature. In addition all the measurement data from different radii of curvature were compared with those from the flat base. We also construct equations that describe the relationship between the illuminance of light source and the output current of different image sensors. By using these equations, we transferred the measurement data from the current intensity distribution into the illumiance distribution, and then were compared with the optical simulation result. The comparison results show that in the case of 40 mm focal length, the illuminance distribution of curved base is up to 9% better than flat base; in the case of 60 mm focal length, the illuminance distribution of curved base is up to 17% better than flat base; in the case of 120 mm focal length, the illuminance distribution of curved base is up to 1% better than flat base. In this research, we successfully fabricate a stretchable and curved image sensor array with a concept of embedding silicon chips into PDMS film and connecting these chips through wire bonding. From a series tests, analyses, and discussions about the image sensor array, we do show that the concept is very feasible.