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Small injectable chips use ultrasound to monitor vital signs

Columbia University engineers have developed a one-chip system with a fully functioning electronic circuit small enough to be injected into the body with a hypodermic needle to help control medical conditions.

Researchers are increasingly interested in designing wireless, miniaturized implantable medical devices for in vivo and in situ physiological monitoring.

These devices can monitor physiological conditions, such as temperature, blood pressure, glucose and respiration, for both diagnostic and therapeutic procedures.

To date, conventional implanted electronics have been very volume-inefficient – they require multiple chips, packages, wires and external transducers, and they often require batteries for energy storage.

A constant trend in electronics has been the closer integration of electronic components, often moving more functions to the integrated circuit itself.

With this, Columbia engineers report that they believe they have built the world’s smallest single-chip system, with a total volume of less than 0.1 mm3.

The system is as small as a dust mite and only visible under a microscope; the researchers said. To accomplish this, the team used ultrasound to both power the device and communicate with the device wirelessly.

“We wanted to see how far we could push the boundaries of how small a working chip we could make,” said Ken Shepard, professor of electrical engineering and professor of biomedical engineering.

“This is a new idea of ​​’chip as a system’ – this is a chip that alone, with nothing else, is a fully functioning electronic system. This should be revolutionary for developing wireless, miniaturized implantable medical devices that can do a variety of things. perceive, can be used in clinical applications, and are ultimately approved for human use. “

Chip shown on the tip of an injection needle.

PhD candidate Chen Shi designed the chip. And according to the researchers, Shi’s design is unique in its volumetric efficiency, the amount of function contained in each volume.

Traditional radio frequency (RF) communication links are not possible for a device this small because the wavelength of the electromagnetic wave is too large for the size of the device.

To address this, the engineers used ultrasound to both power the device and communicate with the device wirelessly since the wavelengths at a given frequency are much smaller because the speed of sound is so much less than the speed of light.

They manufactured the “antenna” for communication and power with ultrasound directly on top of the chip.

The chip, which is the full implantable / injectable substance with no additional packaging, was manufactured at the Taiwan Semiconductor Manufacturing Company with additional process modifications performed at the Columbia Nano Initiative clean room and the City University of New York Advanced Science Research Center (ASRC) Nano fabrication Facility.

“This is a great example of ‘beyond Moore’ technology – we have introduced new materials on standard complementary metal oxide semiconductors to provide a new function,” explains Shepard.

added the integrated circuit to convert acoustic energy into electrical energy. ”Elisa Konofagou, a professor of biomedical engineering and professor of radiology, added,“ Ultrasound is becoming increasingly important in clinical importance as new tools and techniques become available.

continues this trend. ”The team’s goal is to develop chips that medical experts can inject into the body with a hypodermic needle and then communicate back out of the body via ultrasound to provide information about something they measure locally.