Tag Archives: Xu Wang

Protein wires for nanoelectronics

A February 24, 2022 news item on phys.org describes research into using proteins as electrical conductors,

Proteins are among the most versatile and ubiquitous biomolecules on earth. Nature uses them for everything from building tissues to regulating metabolism to defending the body against disease.

Now, a new study shows that proteins have other, largely unexplored capabilities. Under the right conditions, they can act as tiny, current-carrying wires, useful for a range human-designed nanoelectronics.

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A February 25, 2022 Arizona State University (ASU) news release (also on EurekAlert but published February 24, 2022), which originated the news item, delves further into the intricacies of nanoelectronics (Note: Links have been removed),

In new research appearing in the journal ACS Nano, Stuart Lindsay and his colleagues show that certain proteins can act as efficient electrical conductors. In fact, these tiny protein wires may have better conductance properties than similar nanowires composed of DNA [deoxyribonucleic acid], which have already met with considerable success for a host of human applications. 

Professor Lindsay directs the Biodesign Center for Single-Molecule Biophysics. He is also professor with ASU’s Department of Physics and the School of Molecular Sciences.

Just as in the case of DNA, proteins offer many attractive properties for nanoscale electronics including stability, tunable conductance and vast information storage capacity. Although proteins had traditionally been regarded as poor conductors of electricity, all that recently changed when Lindsay and his colleagues demonstrated that a protein poised between a pair of electrodes could act as an efficient conductor of electrons.

The new research examines the phenomenon of electron transport through proteins in greater detail. The study results establish that over long distances, protein nanowires display better conductance properties than chemically-synthesized nanowires specifically designed to be conductors. In addition, proteins are self-organizing and allow for atomic-scale control of their constituent parts.

Synthetically designed protein nanowires could give rise to new ultra-tiny electronics, with potential applications for medical sensing and diagnostics, nanorobots to carry out search and destroy missions against diseases or in a new breed of ultra-tiny computer transistors. Lindsay is particularly interested in the potential of protein nanowires for use in new devices to carry out ultra-fast DNA and protein sequencing, an area in which he has already made significant strides.

In addition to their role in nanoelectronic devices, charge transport reactions are crucial in living systems for processes including respiration, metabolism and photosynthesis. Hence, research into transport properties through designed proteins may shed new light on how such processes operate within living organisms.

While proteins have many of the benefits of DNA for nanoelectronics in terms of electrical conductance and self-assembly, the expanded alphabet of 20 amino acids used to construct them offers an enhanced toolkit for nanoarchitects like Lindsay, when compared with just four nucleotides making up DNA.

Transit Authority

Though electron transport has been a focus of considerable research, the nature of the flow of electrons through proteins has remained something of a mystery. Broadly speaking, the process can occur through electron tunneling, a quantum effect occurring over very short distances or through the hopping of electrons along a peptide chain—in the case of proteins, a chain of amino acids.

One objective of the study was to determine which of these regimes seemed to be operating by making quantitative measurements of electrical conductance over different lengths of protein nanowire. The study also describes a mathematical model that can be used to calculate the molecular-electronic properties of proteins.

For the experiments, the researchers used protein segments in four nanometer increments, ranging from 4-20 nanometers in length. A gene was designed to produce these amino acid sequences from a DNA template, with the protein lengths then bonded together into longer molecules. A highly sensitive instrument known as a scanning tunneling microscope was used to make precise measurements of conductance as electron transport progressed through the protein nanowire.

The data show that conductance decreases over nanowire length in a manner consistent with hopping rather than tunneling behavior of the electrons. Specific aromatic amino acid residues, (six tyrosines and one tryptophan in each corkscrew twist of the protein), help guide the electrons along their path from point to point like successive stations along a train route. “The electron transport is sort of like skipping stone across water—the stone hasn’t got time to sink on each skip,” Lindsay says.

Wire wonders

While the conductance values of the protein nanowires decreased over distance, they did so more gradually than with conventional molecular wires specifically designed to be efficient conductors.

When the protein nanowires exceeded six nanometers in length, their conductance outperformed molecular nanowires, opening the door to their use in many new applications. The fact that they can be subtly designed and altered with atomic scale control and self-assembled from a gene template permits fine-tuned manipulations that far exceed what can currently be achieved with conventional transistor design.

One exciting possibility is using such protein nanowires to connect other components in a new suite of nanomachines. For example, nanowires could be used to connect an enzyme known as a DNA polymerase to electrodes, resulting in a device that could potentially sequence an entire human genome at low cost in under an hour. A similar approach could allow the integration of proteosomes into nanoelectronic devices able to read amino acids for protein sequencing.

“We are beginning now to understand the electron transport in these proteins. Once you have quantitative calculations, not only do you have great molecular electronic components, but you have a recipe for designing them,” Lindsay says. “If you think of the SPICE program that electrical engineers use to design circuits, there’s a glimmer now that you could get this for protein electronics.”

Here’s a link to and a citation for the paper,

Electronic Transport in Molecular Wires of Precisely Controlled Length Built from Modular Proteins by Bintian Zhang, Eathen Ryan, Xu Wang, Weisi Song, and Stuart Lindsay. ACS Nano 2022, 16, 1, 1671–1680 DOI: https://doi.org/10.1021/acsnano.1c10830 Publication Date:January 14, 2022 Copyright © 2022 American Chemical Society

This paper is behind a paywall.

You mean Fitbit makes mistakes? More accuracy with ‘drawn-on-skin’ electronics

A July 30, 2020 news item on ScienceDaily announces news about more accurate health monitoring with electronics applied directly to your skin,

A team of researchers led by Cunjiang Yu, Bill D. Cook Associate Professor of Mechanical Engineering at the University of Houston, has developed a new form of electronics known as “drawn-on-skin electronics,” allowing multifunctional sensors and circuits to be drawn on the skin with an ink pen.

The advance, the researchers report in Nature Communications, allows for the collection of more precise, motion artifact-free health data, solving the long-standing problem of collecting precise biological data through a wearable device when the subject is in motion.

The imprecision may not be important when your FitBit registers 4,000 steps instead of 4,200, but sensors designed to check heart function, temperature and other physical signals must be accurate if they are to be used for diagnostics and treatment.

A July 30, 2020 University of Houston news release (also on EurekAlert) by Jeannie Kever, which originated the news item, goes on to explain why you might want to have electronics ‘drawn on your skin’,

The drawn-on-skin electronics are able to seamlessly collect data, regardless of the wearer’s movements.  

They also offer other advantages, including simple fabrication techniques that don’t require dedicated equipment.

“It is applied like you would use a pen to write on a piece of paper,” said Yu. “We prepare several electronic materials and then use pens to dispense them. Coming out, it is liquid. But like ink on paper, it dries very quickly.”

Wearable bioelectronics – in the form of soft, flexible patches attached to the skin – have become an important way to monitor, prevent and treat illness and injury by tracking physiological information from the wearer. But even the most flexible wearables are limited by motion artifacts, or the difficulty that arises in collecting data when the sensor doesn’t move precisely with the skin.

The drawn-on-skin electronics can be customized to collect different types of information, and Yu said it is expected to be especially useful in situations where it’s not possible to access sophisticated equipment, including on a battleground.

The electronics are able to track muscle signals, heart rate, temperature and skin hydration, among other physical data, he said. The researchers also reported that the drawn-on-skin electronics have demonstrated the ability to accelerate healing of wounds.

In addition to Yu, researchers involved in the project include Faheem Ershad, Anish Thukral, Phillip Comeaux, Yuntao Lu, Hyunseok Shim, Kyoseung Sim, Nam-In Kim, Zhoulyu Rao, Ross Guevara, Luis Contreras, Fengjiao Pan, Yongcao Zhang, Ying-Shi Guan, Pinyi Yang, Xu Wang and Peng Wang, all from the University of Houston, and Jiping Yue and Xiaoyang Wu from the University of Chicago.

The drawn-on-skin electronics are actually comprised of three inks, serving as a conductor, semiconductor and dielectric.

“Electronic inks, including conductors, semiconductors, and dielectrics, are drawn on-demand in a freeform manner to develop devices, such as transistors, strain sensors, temperature sensors, heaters, skin hydration sensors, and electrophysiological sensors,” the researchers wrote.

This research is supported by the Office of Naval Research and National Institutes of Health.

Caption: A new form of electronics known as “drawn-on-skin electronics” allows multifunctional sensors and circuits to be drawn on the skin with an ink pen. Credit: University of Houston

Here’s a link to and a citation for the paper,

Ultra-conformal drawn-on-skin electronics for multifunctional motion artifact-free sensing and point-of-care treatment by Faheem Ershad, Anish Thukral, Jiping Yue, Phillip Comeaux, Yuntao Lu, Hyunseok Shim, Kyoseung Sim, Nam-In Kim, Zhoulyu Rao, Ross Guevara, Luis Contreras, Fengjiao Pan, Yongcao Zhang, Ying-Shi Guan, Pinyi Yang, Xu Wang, Peng Wang, Xiaoyang Wu & Cunjiang Yu. Nature Communications volume 11, Article number: 3823 (2020) DOI: https://doi.org/10.1038/s41467-020-17619-1

This paper is open access.

Not origami but kirigami-inspired foldable batteries

Origami is not noted for its stretchy qualities, a shortcoming according to a June 16, 2015 news item on Azonano,

Origami, the centuries-old Japanese paper-folding art, has inspired recent designs for flexible energy-storage technology. But energy-storage device architecture based on origami patterns has so far been able to yield batteries that can change only from simple folded to unfolded positions. They can flex, but not actually stretch.

Now an Arizona State University [ASU] research team has overcome the limitation by using a variation of origami, called kirigami, as a design template for batteries that can be stretched to more than 150 percent of their original size and still maintain full functionality.

A June 15, 2015 ASU news release, which originated the news item, provides a few more details about the kirigami-influenced batteries (Note: A link has been removed),

A paper published on June 11 [2015] in the research journal Scientific Reports describes how the team developed kirigami-based lithium-ion batteries using a combination of folds and cuts to create patterns that enable a significant increase in stretchability.

The kirigami-based prototype battery was sewn into an elastic wristband that was attached to a smart watch. The battery fully powered the watch and its functions – including playing video – as the band was being stretched.

“This type of battery could potentially be used to replace the bulky and rigid batteries that are limiting the development of compact wearable electronic devices,” Jiang said.

Such stretchable batteries could even be integrated into fabrics – including those used for clothing, he said.

The researchers have provided a video demonstrating the kirigami-inspired battery in action,

Here’s a link to and a citation for the paper,

Kirigami-based stretchable lithium-ion batteries by Zeming Song, Xu Wang, Cheng Lv, Yonghao An, Mengbing Liang, Teng Ma, David He, Ying-Jie Zheng, Shi-Qing Huang, Hongyu Yu & Hanqing Jiang. Scientific Reports 5, Article number: 10988 doi:10.1038/srep10988 Published 11 June 2015

This is an open access paper.

According to the ASU news release, the team published a previous paper on origami-inspired batteries and some of the problems associated with them (Note: Links have been removed),

An earlier paper in the research journal Nature Communications by Jiang and some of his research team members and other colleagues provides an in-depth look at progress and obstacles in the development of origami-based lithium-ion batteries.

The paper explains technical challenges in flexible-battery development that Jiang says his team’s kirigami-based devices are helping to solve.

Read more about the team’s recent progress and the potential applications of stretchable batteries in Popular Mechanics, the Christian Science Monitor, Yahoo News and the Daily Mail.

Here’s a link to and a citation for the team’s earlier paper,

Origami lithium-ion batteries by Zeming Song, Teng Ma,    Rui Tang, Qian Cheng, Xu Wang, Deepakshyam Krishnaraju, Rahul Panat, Candace K. Chan, Hongyu Yu, & Hanqing Jiang. Nature Communications 5, Article number: 3140 doi:10.1038/ncomms4140 Published 28 January 2014

This paper is behind a paywall but there is a free preview available via ReadCube Access.

On a related note, Dexter Johnson has written up Binghamton University research into paper-based origami batteries powered by the respiration of bacteria in a June 16, 2015 posting on his Nanoclast blog.