A tiny implant developed by researchers in the U.S. and Korea can control neural circuits in the brain.

Researchers from the Korea Advanced Institute of Science and Technology (KAIST) and the University of Washington in Seattle, publishing in Nature Biomedical Engineering, said they believe the device, which is controlled by a smartphone can speed up efforts to uncover brain diseases such as Parkinson's, Alzheimer's, addiction, depression, and pain.

The device, using Lego-like replaceable drug cartridges and powerful Bluetooth low-energy, can target specific neurons of interest using drug and light for prolonged periods.

"The wireless neural device enables chronic chemical and optical neuromodulation that has never been achieved before," lead author Raza Qazi, a researcher with KAIST and University of Colorado Boulder.

To achieve chronic wireless drug delivery, scientists had to solve the critical challenge of exhaustion and evaporation of drugs. Researchers collaborated to invent a neural device with a replaceable drug cartridge, which could allow neuroscientists to study the same brain circuits for several months without worrying about running out of drugs.

These 'plug-n-play' drug cartridges were assembled into a brain implant for mice with a soft and ultrathin probe (thickness of a human hair), which consisted of microfluidic channels and tiny LEDs (smaller than a grain of salt), for unlimited drug doses and light delivery.

Controlled with an elegant and simple user interface on a smartphone, neuroscientists can easily trigger any specific combination or precise sequencing of light and drug deliveries in any implanted target animal without need to be physically inside the laboratory.

Using these wireless neural devices, researchers could also easily set up fully automated animal studies where the behavior of one animal could positively or negatively affect behavior in other animals by a conditional triggering of light and/or drug delivery.