Enming Song

Silicon Thin Film

Institute of Optoelectronics, Fudan University

220 Handan Road, Shanghai 200433, China

Email: sem@fudan.edu.cn

 

Biography

 

 

 

Abstract for Presentation

Flexible Neural Electronic Interfaces with Single-Crystalline Silicon-Nanomembrane Transistor Array

 

 

    Flexible engineered systems that establish high-performance, long-lived electrical interfaces to the brain, at a variety of scales ranging from individual-neuron resolution level to macroscopic area coverage, are of particular interest to the neuroscience and biomedical researches [1-4]. Conventional material approaches of state-of-art, fully-integrated electronic systems, such as deep brain stimulators, pacemakers and cochlear implants, generally feature stiff, thick (millimeter-scale) materials constructed by bulk metal, ceramics and wafers [5]. These resulting systems directly contact or insert into adjacent surface of bio-tissues by passive, rigid electrodes, where the materials used for these systems are fundamentally mismatched with the curved, compliant and time-dynamic tissues, with the potential of injury and associated foreign-body response that induces device degradation at biotic/electrode interfaces [6]. Here, our work reports a scalable approach with microscale transfer-printing technology to establish flexible bioelectronic systems that can integrate tens of thousands of single-crystalline silicon nanomembrane (Si-NM) transistors (100 nm thick) in interconnected arrays as functional neural interfaces on thin polymer substrates across full-scale brain dimension [4,7,8]. Specifically, the advanced technology has been exploited for deterministic assembly of prefabricated microelectronic devices sourced from semiconductor wafers, using patterned poly (dimethylsiloxane) (PDMS) stamps [7,9]. This scheme, as shown in Figures 1a and 1b, can support rapid, parallel transfer of large collections of variable types of devices (e.g. > 32,000 CMOS transistors and inorganic light emitted diodes) from rigid, planar silicon wafers to shape-conformal membranes as receiving surfaces, with various densities and pitch spacings across large areas (~150 cm2) on polymer films for neural electrophysiological mapping [7,10,11]. The scales of the demonstrated electronic neural interfaces yield significance of importance, with magnitudes of values that greatly surpass those from previous publications [12]. Furthermore, subsequent co-integration of these bioelectronic systems with thermally grown SiO2 at submicron thickness that serves as biofluid barriers can offer long-term stability, over projected lifetime across many decades of in-vivo implantation in human brain [6,10]. These results will create significant opportunities for flexible bio-integrated electronic systems as chronic neural implants in animal model studies and human healthcare.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fig. 1. Photographs of a large collection of silicon nanomembrane transistors (total ~32,000) printed on a large polymer film

cut into the approximate outline of a human brain,while flat (a) and bent (b). Inset shows device yield as function of printing number.

 

 

Acknowledgement: This work is supported by Shanghai Municipal Science and Technology Major Project (No.2018SHZDZX01), ZJ Lab, and Shanghai Center for Brain Science and Brain-Inspired Technology.

 

 

 

References

[1] E. Song, et al., “Materials for flexible bioelectronic systems as chronic neural interfaces," Nat. Mater., 19 (2020) 590.

[2] E. Song, et al., “Miniaturized electromechanical devices for the characterization of the biomechanics of deep tissue." Nat. Biomed. Eng., 5, (2021) 759.

[3] S. M. Won#, E. Song#, J. Reeder# & J. A. Rogers*, “Emerging modalities and implantable technologies for neuromodulation," Cell, 181 (2020) 115 (Co-first Author).

[4] E. Song et al., “Flexible electronic/optoelectronic microsystems with scalable designs for chronic biointegration,” Proc. Natl. Acad. Sci., 116 (2019) 15398.

[5] E. Song et al., “Ultrathin trilayer assemblies as long-lived barriers against water and ion penetration in flexible bioelectronic systems,” ACS Nano, 12 (2018) 10317.

[6] E. Song, J. Li & J. A. Rogers, “Barrier materials for flexible bioelectronic implants with chronic stability—current approaches and future directions,” APL Mater., 7 (2019) 050902.

[7] E. Song et al., “Thickness-dependent electronic transport in ultrathin single crystalline silicon nanomembranes," Adv. Electron. Mater., 5 (2019) 1900232.

[8] E. Song et al., “Schottky contact on ultra-thin silicon nanomembranes under light illumination,” Nanotechnology, 25 (2014) 485201.

[9] E. Song et al., “Bendable photodetector on fibers wrapped with flexible ultra-thin single crystalline silicon nanomembranes,” ACS Appl. Mater. Interfaces, 9 (2017) 12171.

[10] E. Song et al., “Transferred, ultrathin oxide bilayers as biofluid barriers for flexible electronic implants,” Adv. Funct. Mater., 28 (2018) 1702284.

[11] E. Song, et al., “Thin, transferred layers of silicon dioxide and silicon nitride as water and ion barriers for implantable flexible electronic systems." Adv. Electron. Mater., 3 (2017) 1700077.

[12] S. M. Won#, E. Song#, J. Zhao, J. Li, J. Rivnay & J.A. Rogers*, "Recent advances in materials, devices, and systems for neural interfaces," Adv. Mater., 30 (2018)1800534 (Co-first Author).