RUDN Professor Proposes Nanoporous Silicon Making Technique for Neuroprocessors

RUDN professor suggested the way to create porous silicon nanostructures strictly on a given region. This will help forming the silicon substrate with neurons or other biological objects and for example create neuroprocessors. The results are published in Processes.

Particles of nanostructured silicon are about one millionth of a millimeter in a size. It has so many pores that the total surface area in one gram of matter can reach 1000 square meters. Such a space can be used for example to create “microprocessors” from living neurons. To do this, one needs to learn how to obtain such porous nanostructures in the desired isolated zone of the silicon substrate. Associate Professor of RUDN proposed a way to create nanoporous silicon locally. The method will help “settling” neurons or other biological objects on the nanostructure. 

“The main characteristic of nanostructured porous silicon which prevails in most cases of practical applications is a very significant specific surface area. Therefore, the formation of various membrane and electrode structures based on silicon is of considerable interest,” said Ekaterina Gosteva, PhD, Associate Professor of the Nanotechnology and Microsystem Engineering Department of the RUDN Academy of Engineering.

RUDN scientists together with colleagues from MISIS and the Institute of microelectronics technology and high purity materials proposed to use the technique of anode etching to create silicon nanostructures. The essence of the method is in the electrolytic dissolution of the initial substance from the substrate. After that, the desired structure remains on the plate.

The researchers used a small silicon wafer covered on one side with a thin (0.2–0.3 mm) layer of oxide. A ring of durite — a “reinforced” rubber — was placed on it. It separated the area where nanoporous silicon was created. As a result, electric etching does not affect the plate outside the ring. And inside the ring itself, the nanopores are formed evenly. The only exception is a layer of 1 micrometer thickness near the edge of the ring. The pores there become elongated and look like slits.

“Our results suggest that it is practical to localize the porous region on the silicon wafers without any noticeable effect on their structure outside the porous region. The porous structure is fairly uniform throughout the area. The proposed scheme makes it possible to conduct experiments with biological objects – for example, stem cells, neurons and other objects – in a locally formed porous structure,” said Ekaterina Gosteva, PhD, Associate Professor of the Nanotechnology and Microsystem Engineering Department of the RUDN Academy of Engineering.