What materials are used for digital cameras?

Depends. Some are made of plastic, some are made of metal, some are made of a hybrid of both metal and plastic. Expensive cameras tend to be metal.

Although I'm not exactly sure what you're asking, I'll give it a go. The images sensors in most point-and-shoot digital cameras are CMOS chips which digitally capture the light and create the image. In higher-end cameras like DSLR's, CCD's (charged-couple devices) are used since they are more accurate in capturing low-light situations.