Back in early October, I headed to Leuven, Belgium, to attend the IMEC Technology Forum. IMEC specializes in nanotechnology research in information and communication technologies (ICT), healthcare, and energy.
The forum consisted of two days of presentations on IMEC’s various research projects. I also interviewed IMEC president and CEO Luc Van den hove about IMEC, which was celebrating its silver anniversary, and how research there was faring in these tough economic times. You can check out the interview here.
The presentations ran the gamut of research at the facility, including photovoltaics, green radios, medical devices, advanced process technology, the latest in memory technology, extreme ultraviolet lithography, advanced materials, 3D through-silicon-via technology, and a semiconductor scaling roadmap.
A BED OF NAILS
Wolfgang Eberle, project manager of bioelectronic systems at IMEC, discussed the simple electrical communication between two neurons. He pointed out that a neuron can create an electrical signal that travels over a synaptic path to another neuron. When this one-to-one communication is extended to more neurons, you have a network.
This electrical activity makes it possible to interact with neurons. For example, with the appropriate equipment you can sense the electrical activity a neuron creates—small spikes in the microvolt-millivolt range. You can also produce an appropriate electrical spike and use it to stimulate a neuron.
Eberle then explained a process whereby you place neurons onto a chip substrate and create electrodes to interact with them electrically. He made the distinction between a classical planar or flat approach versus the method IMEC is using, which employs nail-like structures. Incredibly enough, cells like the nails and tend to wrap around them. On a flat surface, the cell might sit on the electrode, but then again it may not.
“The Maier method actually uses planar electrodes. The problem is the cell is just sitting on it,” Eberle said. “But the cell can also sit next to the electrode. The cell has no motivation to sit exactly on the electrode, which is of course the best thing. If the cell is sitting on the electrode you only get the signal from that single neuron, not one of the neighboring ones.”
For this and other reasons, Eberle says the planar method has a very bad signal-to-noise ratio. So IMEC’s idea was to change from a planar to a micro-nail electrode.
“The interesting part is that if you do this properly with regards to the dimensions of these nails, the neuron actively tries to find the nail and engulf it,” Eberle said. “So we just have to put the right nails there, put neurons on it, and the neurons themselves will find the nails. This is a major step forward.”
Eberle says this means any contact on the chip, any nail, will connect with only one single neuron. So, if you were to stimulate a particular neuron, it would not affect any others. And, of course, you only want to see an effect on the others if the neuron you stimulated reacts to the electrical signal and then produces a signal itself that travels to the next neuron.
TRYING OUT A PORTABLE EEG
Eberle also demonstrated a miniaturized, wireless, eight-channel electroencephalogram (EEG) system. His partner in the presentation, Lindsay Brown, a researcher from the Holst Centre in Eindhoven in the Netherlands, wore the device on her head, while Eberle monitored it remotely from a PC.
At the heart of the system is IMEC’s eight-channel ultra low-power analog readout ASIC. The electronics, including ASIC, radio, and controller chips, are integrated on a printed-circuit board that measures only 47 by 27 mm and fits neatly into the front of the head piece. The system consumes only 1.8 mA, which translates into more than three days of operation with a 160-mAh Lithium-ion battery.
I got to try out the head gear at the STUK art center in Leuven at an exhibit called Staalhemel (Steel sky), a work of art by Christoph De Boeck. Staalhemel (www.staalhemel.com) is composed of 80 steel plates suspended from the ceiling of a large hall.
I walked around the hall while wearing the headset, and my brain signals caused tiny hammers to tap on the steel plates, creating quite a din. Some of my colleagues were able to control the cacophony, though I didn’t have much luck. We captured this acoustic representation of my electrical brain activity on video for Engineering TV.
Patients can walk around with this head gear, which is a black plastic “crown” with eight electrodes, for more natural readings and greatly increased comfort compared to a standard EEG system. The data from the head piece is wirelessly transmitted in real time to a receiver, which can be located up to 10 m away.
IMEC has also developed algorithms to interpret the brain signals, linking the brain activity to the degree of relaxation. Applications include comfortable ambulatory monitoring of epileptic patients, e-learning, and gaming.