Recording synaptic connections; crystal stores terabytes of data; determining plasma equipment lifetime.
Researchers from Harvard University built a silicon chip capable of recording synaptic signals from a large number of neurons and used it to catalogue more than 70,000 synaptic connections from about 2,000 rat neurons. They hope the device is a step in creating a detailed synaptic connection map of the brain.
The chip contains an array of 4,096 microhole electrodes. The individual microholes are similar to patch-clamp electrodes, considered the gold standard in intracellular neuronal recording, but can operate in parallel.
“The integrated electronics in the silicon chip plays as equally an important role as the microhole electrode, providing gentle currents in an elaborate way to obtain intracellular access, and recording at the same time the intracellular signals,” said Woo-Bin Jung, a former postdoctoral researcher at Harvard and now a faculty member at Pohang University of Science and Technology, in a statement.
Left: Packaged silicon chip with a microhole electrode array on top. Right: A neuronal cell sitting on a microhole electrode array (in actual recording, neurons are much more densely settled). (Credit: Donhee Ham Research Group / Harvard SEAS)
On average, 90% of the 4,096 microhole electrodes were intracellularly coupled to neurons on top and were able to record many more synaptic connections compared to the team’s previous array that used nanoneedles. The quality of the recording data allowed the team to categorize each synaptic connection based on its characteristics and strengths.
“One of the biggest challenges, after we succeeded in the massively parallel intracellular recording, was how to analyze the overwhelming amount of data,” said Donhee Ham, professor of engineering and applied sciences at Harvard, in a statement. “We have since come a long way to gain insight into synaptic connections from them. We are now working toward a newer design that can be deployed in a live brain.” [1]
Researchers from the University of Chicago devised a technique to store data in atomic crystal defects.
The memory storage device is based on adding ions of the lanthanide rare-earth element Praseodymium to an Yttrium oxide crystal, although the researchers said a variety of materials could be used. The storage device is activated by an ultraviolet laser that stimulates the lanthanides, which in turn release electrons. The electrons are trapped by some of the oxide crystal’s defects.
“It’s well known that rare earths present specific electronic transitions that allows you to choose specific laser excitation wavelengths for optical control, from UV up to near-infrared regimes,” said Leonardo França, a postdoctoral researcher at UChicago PME, in a press release. “It’s impossible to find crystals – in nature or artificial crystals – that don’t have defects. So what we are doing is we are taking advantage of these defects.”
The researchers were able to guide when defects were charged and when they weren’t. By designating a charged gap as “one” and an uncharged gap as “zero,” they were able to turn the millimeter cube of crystal into a memory storage device containing at least a billion memory cells based on atoms.
“Each memory cell is a single missing atom – a single defect,” said Tian Zhong, an assistant professor at UChicago PME, in a press release. “Now you can pack terabytes of bits within a small cube of material that’s only a millimeter in size.” [2]
Researchers from the Korea Research Institute of Standards and Science, Hanyang University, and SK Hynix developed a measurement system that diagnoses the lifetime of parts used in the semiconductor plasma processes in real time to help preemptively prevent contaminant particles generated by corrosion of components.
Contaminant particles generated when the internal coatings of process equipment corrode in the plasma environment can create defects when they fall on the wafer or reduce process performance when they deposit on the interior of the chamber. However, remaining component lifetime is determined based on either indirect observations of a wafer after the process or time-consuming equipment disassembly.
To monitor the status of parts inside the chamber in real time, the team created a measurement system that consists of a test sample holder, a capture device, and an analysis sensor. After attaching a test sample inside the plasma process equipment, the film of the component peeled off due to plasma exposure is captured and analyzed by the sensor. According to the researchers, the system is capable of analyzing thousands of fine particles of a few micrometers or less generated during the process, enabling real-time diagnosis of the status and remaining lifespan of the components.
The new system also serves as a test bed for semiconductor equipment and component manufacturers in Korea to test the performance of prototypes and obtain official test results. [3]
[1] Wang, J., Jung, WB., Gertner, R.S. et al. Synaptic connectivity mapping among thousands of neurons via parallelized intracellular recording with a microhole electrode array. Nat. Biomed. Eng (2025). https://doi.org/10.1038/s41551-025-01352-5
[2] França, Leonardo V. S., Doshi, Shaan, Zhang, Haitao and Zhong, Tian. All-optical control of charge-trapping defects in rare-earth doped oxides. Nanophotonics, 2025. https://doi.org/10.1515/nanoph-2024-0635
[3] So, Jongho, Choi, Eunmi, Kim, Minjoong, et al. Effect of controlling residual moisture in atmospheric plasma spray-Y2O3 coatings on random defect generation by halogen-based plasma, Journal of the European Ceramic Society (2024). https://dx.doi.org/10.1016/j.jeurceramsoc.2024.116919
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