Columbia Engineers develops the smallest single-chip system with a fully functioning electronic circuit.
This implantable chip that is only seen under a microscope shows a future characterized by chips that can be injected into the body with a hypodermic needle to monitor medical conditions.
Implantable medical devices, inner revolution
They are already used extensively for monitoring and mapping biological signals. Or to support and improve physiological functions. Even to cure diseases.
Implantable medical devices are transforming healthcare and improving the quality of life for millions of people.
However, the researchers are focused on devices that can transmit data in vivo and in situ in real time. Having temperature, blood pressure, glucose and breathing under control 24 hours a day as in a dashboard would revolutionize both diagnostic and therapeutic procedures.
A footprint to get rid of
To date, conventional implanted electronics are highly inefficient in terms of volume: requiring more chips, packaging, cables and external transducers. More importantly, batteries are often needed for energy storage.
A constant trend in electronics has been the tighter integration of electronic components, often moving more and more functions onto the integrated circuit itself.
Columbia Engineering researchers have built what they say is the smallest single-chip system in the world. It occupies a total volume of less than 0,1 mm3.
A chip as small as a dust mite, and visible only under a microscope.
To achieve this, the team used ultrasound to both power and communicate with the device wirelessly.
The study was published online in Science Advances.
“We wanted to see how far we could push the limits on how small we could make a working chip,” says the study leader Ken Shepard, professor of electrical and biomedical engineering.
A new idea of chip as a system
Nothing else is needed: the chip alone is a fully functional electronic system.
It could be a revolutionary approach to developing wireless miniaturized implantable medical devices that can sense different things, be used in clinical applications and possibly even for human use.
The project was carried out by doctoral student Chen Shi, who is the first author of the study.
Shi's design is unique in its volumetric efficiency. Traditional RF communication links are not possible for such a small device, because the wavelength of the electromagnetic wave is too large compared to the size of the device.
Because ultrasound wavelengths are much smaller at a given frequency (the speed of sound is much slower than the speed of light) the team used ultrasound to both power and communicate with the device wirelessly.
The team thus fabricated the “antenna” for communication and ultrasound power directly on top of the chip.
“Invisible” chip to be injected
The chip, implantable/injectable as it is, was manufactured at the Taiwan Semiconductor Manufacturing Company.
Ultrasound continues to grow in clinical importance as new tools and techniques become available. This work continues this trend.
The team's goal is to develop chips that can be injected into the body with a hypodermic needle and then communicate outside via ultrasound, providing information about something they measure locally.
