University of Oxford researchers have made a significant step towards realising miniature bio-integrated devices, capable of directly stimulating cells. The work has been published today in the journalSmall bio-integrated devices that can interact with and stimulate cells could have important therapeutic applications, including the delivery of targeted drug therapies and the acceleration of wound healing. However, such devices all need a power source to operate.
The miniaturized soft power source is produced by depositing a chain of five nanolitre-sized droplets of a conductive hydrogel . Each droplet has a different composition so that a salt concentration gradient is created across the chain. The droplets are separated from their neighbours by lipid bilayers, which provide mechanical support while preventing ions from flowing between the droplets.
In the study, the activated droplet power source produced a current which persisted for over 30 minutes. The maximum output power of a unit made of 50 nanolitre droplets was around 65 nanowatts . The devices produced a similar amount of current after being stored for 36 hours. According to the researchers, the device's modular design would allow multiple units to be combined in order to increase the voltage and/or current generated. This could open the door to powering next-generation wearable devices, bio-hybrid interfaces, implants, synthetic tissues, and microrobots. By combining 20 five-droplet units in series, they were able to illuminate a light-emitting diode, which requires about 2 Volts.