Gel electrophoresis is able to separate proteins according to their molecular weight. The amount of protein can be determined by applying densitometry on the stained gel. The equipment for doing this is typically expensive. The ability to reduce the cost of densitometers will make it available and affordable in laboratories around the world. This in turn will help to advance life science research.

Flatbed scanners have been previously considered but found to be inferior to commercial densitometers. Our investigations have found that the key to high sensitivity measurements come from the use of wavelength limited light that matches the peak absorbance of the gel stain. We then modified the flatbed scanner to perform high sensitivity densitometry [1]. The approach that we have developed requires a optical density wedge to be scanned together with the stained gel. Our investigations have revealed that this wedge has to also be calibrated with wavelength limited light for high accuracy [2].

For wavelength band limited light, we initially used an array of LEDs. This made the illumination device bulky. We have found that this problem can be overcome by adapting the backlighting of a LCD monitor. This is done by using the light guide together with a selected single color fluorescent lamp [3]. As the brightness of fluorescent lamps cannot be controlled electrically, we used a proximity approach to the lightguide to do so.

In all imaging devices, brightness and the recording gain are important factors that determine good measurements. The same applies for flatbed scanner densitometry. We have investigated these factors and developed a methodology to ascertain how brightness and gain can be controlled to yield optimal measurement accuracy [4]. Our results show that sensitivity better than commercial densitometers can be achieved with these schemes.