A truly portable scanner would add another dimension to mobile computing. Using the compact optical configuration single optical fiber imaging (SOFI), a handheld scanner can be built inside a penshaped housing. Here, an image sensor formed on a glass substrate is used. Each photodiode of the image sensor has multiple apertures coupled to multiple optical fibers. The light is transmitted through the glass, the apertures and the fibers successively, and a document is illuminated. Scattered light comes back in the same fibers and is detected by a sensitive part of the photodiode. Therefore, a single fiber is involved to both illuminate the document and detect the reflected light. By incorporating light-absorbing material at the fiber boundaries, optical crosstalk inside the fiber array is suppressed. The design of this SOFI-based scanner is studied in detail. A prototype is developed: the width of its housing and the input length are 13 and 110 mm, respectively. The key components are an image sensor fabricated by a-Si and poly-Si thin film technology, a 2 mm-thick array of optical fibers with 0.9 numerical aperture, and an array of three-color LEDs. Images of color documents and fingerprints are successfully acquired by this scanner.