Pengaruh Komposisi dan Ketebalan Pati Singkong-Graphene Oxide sebagai Sensor Gas untuk Kopi Robusta

Abstract

The development of gas sensors currently relies on the use of composite materials, where cassava starch is used as a matrix and GO as reinforcement. This composit sensor has succesfully detecting gases. In this study studied the effect of composition and thickness. The composite was prepared by mixing cassava starch and GO with a certain composition and it was found that the sensor could detect the aroma of coffee in the form of a conductance response. The best response was obtained at the composition of 0,35 gram GO and 0,65 gram cassava starch with a conductance value of 8.370 x 10-8 S and a response time of 45 seconds. The thickness study was carried out by coating the surface of the electrode using a composite by dripping followed by thickness measurement. The results show that the conductance response increases from 0.097 mm to 0.163 mm of thickness, and the response decreases when the thickness is increased to 0.233 mm, 0.277 mm and also at 0.320 mm. The best response is at a thickness of 0.163 mm with a conductance value of 8.862 x 10-8 S and a response time of 41 seconds. Sensors with optimum composition and thickness were then tested for sensitivity using 3 coffee samples from different plantations. The measurement results showed that the sensitivity increased from 0.0128, 0.0167 and 0.0328 S/g on 45 mL of water, for Garahan, Gumitir and Sidomulyo coffee. The sensor is also quite feasible to use up to a five week after preparation which is shown with a reproducibility value of 2,91%-4,44% with repeatability values from measurements every week ranging from 2.91% -4.95%