Electronic Properties of Molecular Memory Circuits on a Nanoscale Scaffold

Abstract

Significant challenges exist in assembling and interconnecting the building blocks of a nanoscale device and being able to electronically address or measure responses at the molecular level. Here we demonstrate the usefulness of engineered proteins as scaffolds for bottom-up self-assembly for building nanoscale devices out of multiple components. Using genetically engineered cowpea mosaic virus, modified to express cysteine residues on the capsid exterior, gold nanoparticles were attached to the viral scaffold in a specific predetermined pattern to produce specific interparticle distances. The nanoparticles were then interconnected using thiol-terminated conjugated organic molecules, resulting in a three-dimensional network. Network properties were engineered by using molecular components with different I-V characteristics. Networks consisting of molecular wires alone were compared with networks containing voltage controlled molecular switches with two stable conductance states. Using such bistable molecules enabled the formation of switchable molecular networks that could be used in nanoscale memory circuits.

A virus-based nanoplasmonic structure as a surface-enhanced Raman biosensor

“…We have been studying viral protein capsids Smith et al 2013;Soto and Ratna 2010) as scaffolds for fabrication of 3D bio-organic/inorganic nanohybrids for advanced optoelectronics and metamaterials applications (Blum et al 2004(Blum et al , 2005(Blum et al , 2006(Blum et al , 2007(Blum et al , 2011Zhou et al 2012). We recently reported self-assembly of a "BCnanocluster" (BC-NC) (Fontana et al 2014) comprising Au NPs (ranging from 17 nm to 34 nm diameter) covalently bound to the surface of 30 nm diameter cowpea mosaic virus (CPMV) protein capsid.…”

A Multiloop and Full Amplitude Hysteresis Model for Molecular Electronics

“…The original hysteresis graphs which have appeared in the literature and output of the proposed model in each case are shown with solid line and dotted lines, respectively. I/V characteristic of a) an oligo phenylene ethynylene molecule with one nitro side group used after in situ acetate removal to produce the free thiol [27], b) a metal/self-assembled monolayer/organic electrode/metal [29], c) an isolated bipyridyl-dinitro oligophenylene ethynylene dithiol (BPDN) molecule [31], d) a virus-gold-BPDN complexes (BPDN/diPt-CPMV) [32], e) a BPDN/diPt-CPMV network based on measured characteristics of individual BPDN molecules [31], f) a ZnO/aluminum stack [30], g) a ITO/aluminum stack [30], h) a layer of Rose Bengal (143 nm) on ZnO (the outer loop) [30], i) a device consisting of ZnO, 5nm Al2O3, and 80 nm Al (the outer loop) [30]. For (f)-(i), the contact area is 0.0288mm 2 .…”

“…This figure demonstrates that the hysteresis loop exists in the first and third quadrants and passes the (0,0) point; however, the hysteresis graphs have different shapes in general. A survey in the literature was done to find different shapes for hysteresis of molecular devices [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34], some of which are shown in Fig. 4 with solid line (this figure demonstrates the simulation curves generated from the proposed model in dotted lines, which will be discussed later).…”

Nonvolatile memory characteristics of small-molecule memory cells with electron-transport and hole-transport bilayers

“…Organic nonvolatile memory cells have recently attracted much interest because of their simple fabrication process, small device feature size, and high-speed operation [1][2][3][4][5]. Among the various kinds that have been reported are memory cells having a layer of small organic molecules that contains metal nanocrystals produced at an evaporation rate low enough that the crystals oxidize spontaneously during their production [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16].…”

“…Among the various kinds that have been reported are memory cells having a layer of small organic molecules that contains metal nanocrystals produced at an evaporation rate low enough that the crystals oxidize spontaneously during their production [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Because the irregular shape and non-uniform distribution of the nanocrystals in those cells degraded the reproducibility of the memory cell characteristics [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16].…”