The sensors are integrated in a 100-micron sized package containing a silicon IC, photovoltaic converter and inorganic light emitting diodes. The devices have been used to record and report voltage, temperature, pressure and conductivity in a variety of environments.
The devices are fabricated, packaged, and released in parallel using photolithographic techniques, resulting in 10,000 individual sensors per square inch. With production volumes of up to 1 million sensors per 200mm-diameter wafer, each device would be expected to cost less than 1 cent each.
To transfer the LEDs to the silicon wafer the researchers developed an assembly method that requires more than 15 photolithography definitions, 30 different materials and more than 100 steps.
In order to transfer the LEDs to a wafer with the electrical components and integrate them, the researchers developed a complicated assembly method that involved more than 15 layers of photolithography, 30 different materials and more than 100 steps.
The team’s paper, “Microscopic sensors using optical wireless integrated circuits,” was published in the Proceedings of the National Academy of Sciences of the United States of America on April 17.
The collaboration is led by Paul McEuen, professor of physical science, and Alyosha Molnar, associate professor of electrical and computer engineering. Working with the paper’s lead author, Alejandro Cortese, a Cornell Presidential Postdoctoral Fellow, they devised a platform for parallel production of their optical wireless integrated circuits (OWICs)
Next: Startup formed
McEuen, Molnar and Cortese have launched their own company, OWiC Technologies, to commercialize the microsensors. The first application is the creation of e-tags that can be attached to products to help identify them.
OWICs can be used to measure voltage and temperature inside living tissue and microfluidic systems. And as a proof of concept the team successfully embedded an OWIC with a temperature sensor in brain tissue and wirelessly relayed the results.
“The circuits in this paper were quite simple. But you can potentially fit thousands of transistors on one of these devices. And that means you can increase the range of things the device can sense, how the device communicates out, or its ability to complete more complex tasks,” said Cortese, in a statement.
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