This invention provides a composition for a conductive polymer allowing the production of electrodes for detecting electrophysiological signals (e.g. ECG) associated to a impedance variation of the body. Such electrodes can be printed on several types of fabric, including wetsuits and patches.
| Patent title | Conductive polymeric composition and method for preparing the conductive polymeric composition |
|---|---|
| Thematic area | Health |
| Ownership | ARNALDO USAI, ALMA MATER STUDIORUM - UNIVERSITA' DI BOLOGNA, UNIVERSITA DEGLI STUDI DI CAGLIARI |
| Inventors | DANILO PANI, ELEONORA SULAS, ARNALDO USAI, Annalisa Bonfiglio, Erika Scavetta, Beatrice Fraboni, Marta Tessarolo, Isacco Gualandi |
| Protection | International |
| Licensing status | Licensed |
| Keywords | Conductive polymer, electrodes, bioelectrodes, wearable electronics |
| Filed on | 29 April 2019 |
The first examples of textile electrodes (first half of the 2000s) were completely metallic and thus totally unsuitable to be worn because of the mismatch between their mechanical properties and those of the fabric they were supposed to be attached to. Furthermore, they needed gels in order to improve the electrical contact between metallic conductor and skin.
Intrinsically conductive polymers, like PEDOT:PSS, are light, flexible and soft, they can thus be easily integrated in a functionalized garment for a non-invasive control of vital parameters. Nonetheless, the high impedance values of the skin/electrode interface and the dehydration process of the PEDOT:PSS still impose the application of a gel close to the electrodes, which could cause cutaneous rash and reduce the level of comfort of the garment.
Room-temperature ionic liquids are salts with melting point below 100 °C, low vapor pressure, moderate electrical conductivity, thermal stability and a wide electrochemical window. The combination of ionic liquids with PEDOT:PSS allows to control the physico-chemical properties of the polymer and its application in actual devices, such as organic electrochemical transistors, field-effect transistors, gas sensors, electrochemical sensors and transparent flexible electrodes for displays.
Solutions based on PEDOT and ionic liquids were never proposed before for preparing compositions to be used on fabric, nor for producing electrodes for detecting bioelectric parameters.
This invention allows to detect bioelectric signals by using polymeric electrodes printed on fabric thanks to a new formulation, eliminating the need of gels or hydrating solutions.
“Bioelectrical signals” are electrical signals that can be continuously measured on a living being as potentials or currents (e.g. electrocardiogram, electroencefalogram, etc).
The conductive composition includes the couple poly(3,4-ethylenedioxythiophene):anion (PEDOT), preferably as poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), and an imidazolic ionic liquid.
A secondary dopant can be added to increase PEDOT cristallinity. Typical examples are ethylene glycol, dimethylsulfoxyde, dimethylformamide, metoxyethanol, glycerol, sorbitol.
Ionic liquids also have a thickening effect: a mild heating at 1% concentration (1-60 mins at 50-70 °C) provides an adequate viscosity (100-10000 cP) for the desired application, especially for silk-screen printing.
The strong point of the invention is the formulation to be applied on fabric, allowing to obtain PEDOT electrodes for detecting bioelectrical signals without the need of gels or hydrating solutions.
This formulation can be applied on garments, like a shirt, as to be in direct contact with the particular areas subject to monitoring. The products containing the formulation can be flexible and wearable, including wetsuits for scuba diving, water sports, and underwater missions, medical devices such as patches, supporting elastic strips, bioceramic fabric.
Functionalized garments can be washed and retain their electrical response even after 20 washing cycles. The compositions are suitable for direct skin contact and do not cause cutaneous rashes.