Dropletronics

Scientists at Oxford University’s Department of Chemistry have developed a set of biocompatible devices that use ions as the signal carriers. Made from soft hydrogel droplets, these “iontronic” devices are the first to be compatible for use with soft tissues. In the study published in Science, the team demonstrated the technology by recording electrical signals from beating human heart cells.

Iontronics is a rapidly growing field of biochemical engineering. The devices transmit information via charged particles of sodium, potassium, and calcium, amongst others, mimicking cell signaling, which allows them to interface with cells and record signals from them. They have potential for many applications in clinical medicine, including sensing abnormalities in an organ and intelligent drug delivery inside the body.

Iontronics are typically set in solid scaffolds, so their integration with soft tissues has thus far been limited. The Oxford team, however, constructed their “dropletronics” by encasing tiny droplets in a surfactant-based organogel, creating a range of devices, including diodes, transistors, logic gates, and memory devices. In comparison with other soft iontronic devices, the dropletronic collection achieved superior response times and efficiencies. Performance of the dropletronics was comparable with solid iontronics, with the advantage of the flexible construct, which supports more applications within the body.

The researchers tested dropletronics by creating a transistor to record electrophysiological signals from sheets of human heart cells. Co-author of the study, Christopher Toepfer, said, “This is the first example of a lab-built biological sensor that can sense and respond to changes in function of human heart cells in a dish. This finding is an exciting step towards the fabrication of more complex biological devices that will sense a variety of abnormalities in an organ and react by delivering drugs intelligently inside the body.”