High sensitivity conducting polymer sensors

Thermoelectric power and conductivity of different types of polypyrrole

“…5,6 It is of interest to determine what other differences exist in the properties of this new type of polypyrrole compared to comparable electrochemically prepared samples. The recent development of polypyrrole for use in gas sensors 7,8 also gives added impetus to the quest to understand more fully the variations in the behavior of its electronic transport properties and to compare this behavior with that seen in our earlier studies of polyaniline 9 and polyacetylene. 10 In this article, we report and compare measurements of thermoelectric power and conductivity down to low temperatures for a wide variety of different samples of polypyrrole.…”

“…7,8 The electrodes were separated by a 5-m gap, and the films were approximately 50 nm thick. The dopants used were p-toluenesulfonic acid (sample S-pTS in Table I), octanesulfonic acid (S-OS), and Tiron (4,5-dihydroxy-1,3-benzenedisulfonic acid, disodium salt monohydrate, sample S-DHBS).…”

Sensors: From biosensors to the electronic nose

“…The random nature of the deposition process is, however, a problem for the production of reproducible sensors, although the use of four electrodes, instead of two, seems to improve the results (Partridge et al 1996). The sensors have also other drawbacks as their too long response time (20-40 s), in comparison with MOS (Mielle 1996), and their inherent drift over time or with changes in temperature.…”

“…characterisation or authentication). The oxidation state of the polymer can also be changed after deposition to tailor the sensing characteristics (Partridge et al 1996). CPs are resilient to poisoning by the compounds that inactivate the described inorganic semiconductor sensors but surprisingly their lifetime, only about 9-18 months, is shorter.…”

“…These sensors are made of a broad range of monomers that are polymerised by chemical or electrochemical methods. A thin film of polymer is deposited onto a sensing substrate formed by two parallel platinum or gold plated electrodes with a insulating base such as oxidized silicon (Partridge et al 1996). The most common polymers used in the synthesis of CPs are polypyrroles, polyanilines, polytiophenes, butane to decane sulphonic acids, para-toluenesulphonic acid and its tetra-ethylammonium salt, sodium monohydrogenosulphate and tetraethylammonium tetrafluoroborate (Mielle 1996) although new polymers are being synthesized to open these sensors to new applications.…”