We studied electrochemical sensors using printed carbon nanotubes (CNT) film on a polyethylene telephtalate (PET) substrate. The mechanical stability of the printed CNT film (PCF) was confirmed by using bending and Scotch tape tests. In order to determine the optimum sensor structure, a resistance-type PCF sensor (R-type PCF sensor) and a comb-type PCF sensor (C-type PCF sensor) were fabricated and compared using a diluted NH₃ droplet with various concentrations. The magnitude of response, response time, sensitivity, linearity, and limit of detection (LOD) were compared, and it was concluded that C-type PCF sensor has superior performance. In addition, the feasibility of PCF electrochemical sensor was investigated using 12 kinds of hazardous and noxious substances (HNS). The detection mechanism and selectivity of the PCF sensor are discussed.

A chemical sensor was fabricated using indium-tin-oxide (ITO) films printed on biodegradable plastic substrates. The ITO layers were printed on polylactic acid (PLA) films. To optimize the printing procedure, the thermal properties of the PLA substrate were investigated using the differential scanning calorimetry method. The structural and electrical properties of the fabricated ITO films (P-ITO) were compared with commercial sputtered ITO films (S-ITO). X-ray diffraction and Hall effect measurements were used to estimate the grain size and the carrier transportation mechanism of the ITO films. The small grain size of P-ITO was attributed to its scattering mechanism. Grain boundary scattering was shown to be dominant in the P-ITO. The chemical sensing properties were also evaluated using a droplet of methanol (20 µl), indicating that the response rate of the P-ITO film was considerably higher (650%) than that of the S-ITO film. These results were attributed to the large surface area of the P-ITO film.

The feasibility of useing a flexible, printed indium-tin-oxide (ITO) sensor to detect hazardous and noxious substances was investigated. The resistivities of this printed ITO (P-ITO) film and that of a commercial sputtered ITO (S-ITO) film were 35.9 and 1.5 x 10(-4)omega center dot cm, respectively. The corresponding grain sizes, a determined via X-ray diffractometry, were 31.7 and 102.6 nm. This difference in grain size between the two films led to a remarkable difference in the respective carrier scattering mechanisms. To evaluate the chemical sensing property of both ITO films, we tested their NH(3)sensing abilities; the printed film exhibited a higher sensitivity and better electrical properties.