We report the fabrication of a paper-sensor for quantitative detection of α-amylase activity in human
blood serum. Pieces of filter papers were coated with starch–iodine solution leading to an intense blue
coloration on the surface. Dispensing α-amylase solution on the starch–iodine coated paper reduced the
intensity of the color because of starch-hydrolysis catalyzed by amylase. The variation in the intensity of
the color with the concentration of amylase was estimated in three stages: (i) initially, the paper-surface
was illuminated with a light emitting diode, (ii) then, the transmitted (reflected) rays emitted through
(from) the paper were collected on a photoresistor, and (iii) the variations in the electrical resistance of
the photoresistor were correlated with the amylase concentration in analyte. The resistance of photoresistor
decreased monotonically with an increase in amylase concentration because the intensity of the
reflected (transmitted) rays collected from (through) the paper increased with reduction in the color
intensity on the paper surface. Since a specific bio-reaction was employed to detect the activity of
amylase, the sensor was found to be equally efficient in detecting unknown quantities of amylase in
human blood serum. The reported sensor has shown the potential to graduate into a point-of-care detection
tool for α-amylase.