A team from the University of Oxford (United Kingdom) associated with the Federal Polytechnic School of Lausanne (EPFL, Switzerland) has just invented a new technological field, “gutterelectronics” or the art of manipulating electric currents using tiny gel drops. Like semiconductor materials in microelectronics, these compounds are “doped” with different electrical charges. Here, there are no electrons, but sodium or chlorine ions circulating. The combination of positive and negative drops is used to create diodes, transistors, logic gates used to perform calculations, etc., as presented in Science, on November 29. Previously the team created a power source and a battery. The small size (around a hundred micrometers), biocompatibility and sensitivity make it possible to create sensors for biological tissues or cells.
“Many previous devices, based on “iontronics”, the circulation of ions, rely on micro or nanofluidic systems with conductive liquids confined in small channels, Constate Yujia Zhang, de l’EPFL. Our approach is different, ensuring small size but also new functions. Our systems are modular, reconfigurable and suitable for biological measurements. » His team did not invent the term “iontronics”, but designed that of « dropletronic »in English, which can be translated as “electronic drop”. The researcher also explains that classic electronics are not very suitable for measurements on cells because they require larger interfaces as well as higher currents.
Patents protect the manufacture of these drops made of a polymer network based on silk threads which can be negatively and positively charged. The drops also trap charged and mobile salts which cause currents to circulate. Ultraviolet lighting makes it possible to “open” the interface between two adjacent drops so that this current passes between the beads.
The team recognizes that these works are prototypes and that the dropletronic is still in its infancy, but sees a promising future for interfaces with living matter.
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