Paper Title
A Carboxymethyl Cellulose Colorimetric Film Sensor for Carbon Dioxide

A carbon dioxide (CO2) sensor colorimetric film was papered by using the different solution of indicators, including, hydrogencarbonate, bromthymol blue, phenol red and natural indicators such as sappan wood and purple cabbage and carboxymethyl cellulose (CMC) After drying at 45 C for 6 h, the colorimetric films (CF) were obtained. In addition, the colorimetric film coated on papers (CFP) were prepared by immersing the paper in size of 2 cm × 2 cm and in each indicator solution and drying. The both of CF and CFP were tested for CO2 sensors. The result showed that the hydrogencarbonate indicator in both of CF and CFP more clearly changed color from purple to orange than others. The both of CF and CFP with hydrogencarbonate indicator presents purple at pH 9 and changed the color to orange at pH 8 due to CO2 adsorption. Therefore, the both of CF and CFP with hydrogencarbonate indicator were used for fruit ripeness testing by packing with the raw bananas and keeping at room temperature. The color of film was changed to orange in the second day, which the green bananas became ripe. It may be possible to apply to detect food spoilage in food packaging products. Index Terms - CO2 sensor, carboxymethyl cellulose, dye indicators, colorimetric film