Miniaturized amorphous-silicon based chemical imaging sensor system using a mini-projector as a simplified light-addressable scanning source

This paper reports the development of a chemical imaging sensor configuration addressing two important issues of imaging systems: the flexibility of the scanning technique and the resolution of the image. In this set-up, a commercial pico-projector in combination with an objective lens is placed directly below the sensor plate and is utilized as a light-addressing source to scan the sensor surface. The pico-projector provides the computer software interface that enables the user to generate a programmable light beam with control over its size, shape, color, movement, and even modulation frequency. This approach eliminates the requirement of complicated mechanics and optics in conventional scanning techniques based on linear X-Y stages or multiple light sources and effectively miniaturizes the set-up. Furthermore, no additional control unit is required to access the internal control of digital micro-mirror, thus simplifying the scanning set-up. An amorphous-silicon-based thin-film light-addressable potentiometric sensor (LAPS) structure is used as a sensor chip. At the present stage, pH sensitivity close to the ideal Nernstian value and a visibility of patterns of 25 μm chemical image were exhibited. Finally, the chemical imaging of a complex pattern was successfully demonstrated using this simple low-cost, miniaturized system.