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pixies
This is not really nano-technology, just a neat trick in processing. The circuit ...
yalanand
Nanocircuits that adhere to any substrate
R Colin Johnson
8/1/2011 2:13 PM EDT
PORTLAND, Ore.— Researchers at Stanford University recently demonstrated a novel wafer-scale lift-off process for fabricating nanowire-based circuits on reusable silicon wafers, then transferring them to any substrate in any shape.
The research team, led by professor Xiaolin Zheng, claims the flexible circuitry can be used to create anything from paper-thin displays and solar cells to biomedical sensors that attach directly to the tissue being monitored.
"Devices can be transferred without sustaining any damage," said Zheng. "And the detachment process can be done at room temperature in just a few seconds."
The key to the novel process is depositing a sacrificial nickel layer atop a donor silicon wafer which has been pre-coated with insulating silicon dioxide. Next, a flexible polymer just 800 nanometers thick is deposited on the nickel, after which the nanowire circuitry is fabricated which can include field-effect transistors (FETs), diodes and resistors. Once the circuitry is finished, the wafer is submerged into water which detaches the nickel and the circuitry atop its polymer substrate. The whole assembly can then be transferred to nearly any target substrate including paper, plastic, glass or metal.
"The lift-off process only separates the nickel from the silicon wafer," said Zheng. "The nickel can be etched afterwards to leave the polymer only."
After fabrication on a silicon wafer, nanowire-based circuits can be lifted off and transferred to any substrate in any shape.
The silicon wafer is undamaged by the whole process, allowing it to be repeated over-and-over with the same wafer—the donor silicon wafer is merely recoated with nickel before each reuse.
The detached circuitry uses nanowires just two microns long, allowing circuits to be deposited on nearly any shaped target substrate without substantial damage from crimping. The circuits can also be detached and reused, such as for biological sensors deposited on tissue—like the heart—the later removed and reused with other patients.
Zheng performed the work with doctoral candidates Chi Hwan Lee and Dong Rip Kim.
The research team, led by professor Xiaolin Zheng, claims the flexible circuitry can be used to create anything from paper-thin displays and solar cells to biomedical sensors that attach directly to the tissue being monitored.
"Devices can be transferred without sustaining any damage," said Zheng. "And the detachment process can be done at room temperature in just a few seconds."
The key to the novel process is depositing a sacrificial nickel layer atop a donor silicon wafer which has been pre-coated with insulating silicon dioxide. Next, a flexible polymer just 800 nanometers thick is deposited on the nickel, after which the nanowire circuitry is fabricated which can include field-effect transistors (FETs), diodes and resistors. Once the circuitry is finished, the wafer is submerged into water which detaches the nickel and the circuitry atop its polymer substrate. The whole assembly can then be transferred to nearly any target substrate including paper, plastic, glass or metal.
"The lift-off process only separates the nickel from the silicon wafer," said Zheng. "The nickel can be etched afterwards to leave the polymer only."
After fabrication on a silicon wafer, nanowire-based circuits can be lifted off and transferred to any substrate in any shape.
The silicon wafer is undamaged by the whole process, allowing it to be repeated over-and-over with the same wafer—the donor silicon wafer is merely recoated with nickel before each reuse.
The detached circuitry uses nanowires just two microns long, allowing circuits to be deposited on nearly any shaped target substrate without substantial damage from crimping. The circuits can also be detached and reused, such as for biological sensors deposited on tissue—like the heart—the later removed and reused with other patients.
Zheng performed the work with doctoral candidates Chi Hwan Lee and Dong Rip Kim.
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R_Colin_Johnson
8/1/2011 8:08 PM EDT
These researchers claim to be able to fabricate simple sensors and similar circuits that can be directly attached to the objects being monitored. The inexpensive process should enable them to be used for all sorts of interesting applications, such as monitoring food spoilage.
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yalanand
8/3/2011 2:33 AM EDT
Colin,
Thanks for the post. Rusability of nano-circuits is an interesting idea. Any idea when will we see the first product which will use this technology ?
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resistion
8/1/2011 8:30 PM EDT
It's a nice new field, but once the substrate is not taken for granted, stress becomes a much more significant issue.
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kdboyce
8/2/2011 12:12 AM EDT
Lots of applications exist for very simple and targeted sensors capable of adhering to any shape or object. Assuming the circuit performance is stable and repeatable in bulk then adding simple memory to it (for read back later), or perhaps a simple RF or NFC link would be all that you need to get commercially viable (and very cheap) sensor systems.
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goafrit
8/2/2011 10:23 AM EDT
Lot of buzz on nano, yet to see the effect. this will never end, until maybe we just stop writing about them. the promises are not yet.
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pixies
8/4/2011 5:00 PM EDT
This is not really nano-technology, just a neat trick in processing. The circuit is huge and an 800 nm thick film is hardly nano technology.
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