Research Highlight

Humidity shield with potato starch

doi:10.1038/nindia.2012.37 Published online 19 March 2012

Researchers have developed a new biopolymer electrolyte by mixing potato starch and ammonium salt. The electrolyte is immune to changes in humidity and therefore could have potential for use in humidity-immune devices.

The researchers decided to use natural resources such as starch in order to make an eco-friendly polymer film. However, most starch-based films are inflexible and have poor conductivity.

To devise a flexible organic film that exhibits high conductivity, they mixed potato starch and glutaraldehyde. They prepared several polymer films by adding various concentrations of ammonium iodide salt, and then investigated each film's conductivity over a range of temperatures.

Initially, the conductivity increased at a salt content level of 20%, followed by a drop at 40%. The conductivity rose again beyond 40%.

The conductivity rose slightly as the temperature was increased from 20°C to 70°C. At room temperature, the conductivity remained nearly constant up to a relative humidity of 75%, which makes this material immune to atmospheric changes.

Polymer films often decay due to fungal growth. The researchers found that their starch-based films resisted fungal growth due to the presence of glutaraldehyde.

"This electrolyte could replace synthetic polymers in devices," says lead researcher Neelam Srivastava.


  1. Kumar, M. et al. Electrical transport behaviour of bio-polymer electrolyte system: potato starch +ammonium iodide. Carbohydr. Polymer. 88, 54-60 (2012) | Article |