Power/Performance Bits: March 3

Optimizing fiber networks; smartphone diagnostic lab; printed cathodes.


Optimizing fiber networks
Researchers at Chalmers University of Technology are working towards reducing the energy consumption of fiber optic communications before the amount of electricity required by the Internet becomes too great to manage. To improve overall efficiency, the team tackled several aspects of fiber optic cables.

One of the major energy drains the team identified was the error-correction data chips used to compensate for noise and interference. By optimizing these circuits, they were able to see a significant energy reduction.

“Our measurements show that the energy consumption of our refined chips is around 10 times less than conventional error-correcting chips,” said Per Larsson-Edefors, Professor in Computer Engineering at Chalmers.

On the transmitter side, instead of having separate laser transmitters for each frequency channel, the team used optical frequency combs. An optical frequency comb emits light at all wavelengths simultaneously, making the transmitter very frequency-stable. This makes reception of the signals much easier and thus more energy efficient.

The researchers addressed the network side, too. By mathematically modelling the energy consumption in different network resources, data traffic can be controlled and directed so that the resources are utilized optimally, according to the team. This becomes particularly important when traffic varies over time. For this, the researchers developed an optimization algorithm which can reduce network energy consumption by up to 70%.

The project drew scientists from different disciplines, noted Erik Agrell, Professor in Communications Systems at Chalmers. “Improving the energy efficiency of data transmission requires multidisciplinary competence. The challenges lie at the meeting points between optical hardware, communications science, electronic engineering and more. That’s why this project has been so successful.”

Smartphone diagnostic lab
Engineers at the University of Cincinnati developed an add-on for smartphones that can perform simple disease testing and diagnosis using just a patient’s saliva.

About the size of a credit card, the portable lab uses a single-use plastic lab chip, which the patient places in their then plugs into a slot in the box. An app on the phone transmits results to the patient’s doctor.

The lab chip uses natural capillary action to draw a sample down two channels called a “microchannel capillary flow assay.” One channel mixes the sample with freeze-dried detection antibodies. The other contains a freeze-dried luminescent material to read the results when the split samples combine again on three sensors.

UC engineers developed a smartphone app that can record and transmit test results from a portable lab that people can plug into their phones. The lab uses saliva from plastic test strips that people put in their mouths like a sucker. (Photo credit: Joseph Fuqua II/UC Creative Services)

The team used the device for instant testing for malaria, but say the device could be used for smart point of care testing for many chronic or infectious diseases. “The performance is comparable to laboratory tests. The cost is cheaper. And it’s user-friendly,” said Chong Ahn, a professor at University of Cincinnati. “We wanted to make it simple so anyone could use it without training or support.”

Beyond disease diagnosis, the team sees potential for measuring hormones or other biomarkers associated with depression or anxiety to guide mental health treatment.

Being able to use saliva rather than a blood sample is important, noted Sthitodhi Ghosh, a doctoral student at UC. “If you’re stressed from doing a finger prick, it’s already creating a bias in the testing of stress. That’s why we’re moving to a noninvasive method.”

The team is pursuing a patent to commercialize the device.

Printed cathodes
Researchers from ITMO University, Peter the Great St. Petersburg Polytechnic University, and the Ioffe Institute developed a cathode for lithium-ion batteries that can be printed with an inkjet printer. This would allow the cathode thickness to be greatly reduced, making for thinner and lighter batteries that could be stacked in a laptop or tablet.

“We’ve developed the ink for inkjet printing of the cathode material,” said Denis Kolchanov, a PhD student at ITMO’s SCAMT Laboratory. “We’ve managed to apply a layer of about 5 micrometers in thickness on the current collector. Existing industrial samples use cathode materials with a thickness of 100 micrometers. Laboratory samples created on the basis of other technologies give a thickness of 50 micrometers. Therefore, we were able to reduce the thickness by 10-20 times. It’s not possible to make an ever smaller layer with this technology, because a short circuit will occur.”

The ultra-thin current collector could also be used to build a flexible battery that does not deform when bent, which would make designing foldable electronics simpler. “In theory, our development can be used to create such devices,” said Kolchanov. “There is a huge possibility that thin electrodes will be more flexible since they will not deform when bent. This will allow us to use them in transformer devices.”

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