Tag Archives: motion

Bionanomotors for bio-inspired robots on the battlefield

An October 9, 2019 news item on ScienceDaily provides some insight into the latest US Army research into robots,

In an effort to make robots more effective and versatile teammates for Soldiers in combat, Army researchers are on a mission to understand the value of the molecular living functionality of muscle, and the fundamental mechanics that would need to be replicated in order to artificially achieve the capabilities arising from the proteins responsible for muscle contraction.

Caption: Army researchers are on a mission to understand the value of the molecular ‘living’ functionality of muscle, and the fundamental mechanics that would need to be replicated in order to artificially achieve the capabilities arising from the proteins responsible for muscle contraction. Credit: US Army-Shutterstock

An October 8, 2019 US Army Research Laboratory news release (also on EurekAlert but published on October 9, 2019), which originated the news item, delves further into the research,

Bionanomotors, like myosins that move along actin networks, are responsible for most methods of motion in all life forms. Thus, the development of artificial nanomotors could be game-changing in the field of robotics research.

Researchers from the U.S. Army Combat Capabilities Development Command’s [CCDC] Army Research Laboratory [ARL] have been looking to identify a design that would allow the artificial nanomotor to take advantage of Brownian motion, the property of particles to agitatedly move simply because they are warm.

The CCDC ARL researchers believe understanding and developing these fundamental mechanics are a necessary foundational step toward making informed decisions on the viability of new directions in robotics involving the blending of synthetic biology, robotics, and dynamics and controls engineering.

“By controlling the stiffness of different geometrical features of a simple lever-arm design, we found that we could use Brownian motion to make the nanomotor more capable of reaching desirable positions for creating linear motion,” said Dean Culver, a researcher in CCDC ARL’s Vehicle Technology Directorate. “This nano-scale feature translates to more energetically efficient actuation at a macro scale, meaning robots that can do more for the warfighter over a longer amount of time.”

According to Culver, the descriptions of protein interactions in muscle contraction are typically fairly high-level. More specifically, rather than describing the forces that act on an individual protein to seek its counterpart, prescribed or empirical rate functions that dictate the conditions under which a binding or a release event occurs have been used by the research community to replicate this biomechanical process.

“These widely accepted muscle contraction models are akin to a black-box understanding of a car engine,” Culver said. “More gas, more power. It weighs this much and takes up this much space. Combustion is involved. But, you can’t design a car engine with that kind of surface-level information. You need to understand how the pistons work, and how finely injection needs to be tuned. That’s a component-level understanding of the engine. We dive into the component-level mechanics of the built-up protein system and show the design and control value of living functionality as well as a clearer understanding of design parameters that would be key to synthetically reproducing such living functionality.”

Culver stated that the capacity for Brownian motion to kick a tethered particle from a disadvantageous elastic position to an advantageous one, in terms of energy production for a molecular motor, has been illustrated by ARL at a component level, a crucial step in the design of artificial nanomotors that offer the same performance capabilities as biological ones.

“This research adds a key piece of the puzzle for fast, versatile robots that can perform autonomous tactical maneuver and reconnaissance functions,” Culver said. “These models will be integral to the design of distributed actuators that are silent, low thermal signature and efficient – features that will make these robots more impactful in the field.”

Culver noted that they are silent because the muscles don’t make a lot of noise when they actuate, especially compared to motors or servos, cold because the amount of heat generation in a muscle is far less than a comparable motor, and efficient because of the advantages of the distributed chemical energy model and potential escape via Brownian motion.

According to Culver, the breadth of applications for actuators inspired by the biomolecular machines in animal muscles is still unknown, but many of the existing application spaces have clear Army applications such as bio-inspired robotics, nanomachines and energy harvesting.

“Fundamental and exploratory research in this area is therefore a wise investment for our future warfighter capabilities,” Culver said.

Moving forward, there are two primary extensions of this research.

“First, we need to better understand how molecules, like the tethered particle discussed in our paper, interact with each other in more complicated environments,” Culver said. “In the paper, we see how a tethered particle can usefully harness Brownian motion to benefit the contraction of the muscle overall, but the particle in this first model is in an idealized environment. In our bodies, it’s submerged in a fluid carrying many different ions and energy-bearing molecules in solution. That’s the last piece of the puzzle for the single-motor, nano-scale models of molecular motors.”

The second extension, stated Culver, is to repeat this study with a full 3-D model, paving the way to scaling up to practical designs.

Also notable is the fact that because this research is so young, ARL researchers used this project to establish relationships with other investigators in the academic community.

“Leaning on their expertise will be critical in the years to come, and we’ve done a great job of reaching out to faculty members and researchers from places like the University of Washington, Duke University and Carnegie Mellon University,” Culver said.

According to Culver, taking this research project into the next steps with help from collaborative partners will lead to tremendous capabilities for future Soldiers in combat, a critical requirement considering the nature of the ever-changing battlefield.

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

A Dynamic Escape Problem of Molecular Motors by Dean Culver, Bryan Glaz, Samuel Stanton. J Biomech Eng. Paper No: BIO-18-1527 https://doi.org/10.1115/1.4044580 Published Online: August 1, 2019

This paper is behind a paywall.

Creeping gel does ‘The Loco-Motion’

Now it’s the creeping gel’s turn, from an Oct. 24, 2016 news item on phys.org,

Directed motion seems simple to us, but the coordinated interplay of complex processes is needed, even for seemingly simple crawling motions of worms or snails. By using a gel that periodically swells and shrinks, researchers developed a model for the waves of muscular contraction and relaxation involved in crawling. As reported in the journal Angewandte Chemie, they were able to produce two types of crawling motion by using inhomogeneous irradiation.


Courtesy: Angewandte Chemie

Courtesy: Angewandte Chemie

An Oct. 24, 2016 Angewandte Chemie (Wiley) press release (also on EurekAlert), which originated the news item, explains further,

Crawling comes from waves that travel through muscle. These waves can travel in the same direction as the animal is crawling (direct waves), from the tail end toward the head, or in the opposite direction (retrograde waves), from the head toward the tail. While land snails use the former type of wave, earthworms and limpets use the latter. Chitons (polyplacophora) can switch between both types of movement.

With the aid of a chemical model in the form of a self-oscillating gel, researchers working with Qingyu Gao at the China University of Mining and Technology (Jiangsu, China) and Irving R. Epstein at Brandeis University (Waltham, Massachusetts, USA) have been able to answer some of the many questions about these crawling processes.

A gel is a molecular network with liquid bound in the gaps. In this case, the liquid contains all of the ingredients needed for an oscillating chemical reaction (“chemical clock”). The researchers incorporated one component of their reaction system into the network: a ruthenium complex. During the reaction, the ruthenium periodically switches between two oxidation states, Ru2+ and Ru3+. This switch changes the gel so that in one state it can hold more liquid than the other, so the gel swells and shrinks periodically. Like the chemical clock, these regions propagate in waves, similar to the waves of muscle contractions in crawling.

The complex used in this gel also changes oxidation state when irradiated with light. When the right half of the gel is irradiated more strongly than the left, the waves move from right to left, i.e., from a high- to a low-frequency region of gel oscillations. Once the difference in intensity of irradiation reaches a certain threshold, it causes a wormlike motion of the gel from left to right, retrograde wave locomotion. If the difference is increased further, the gel comes to a stop. A further increase in the difference causes the gel to move again, but in the opposite direction, i.e., direct wave locomotion. The nonuniform illumination plays a role analogous to that of anchoring segments and appendages (such as limbs and wings) during cell migration and animal locomotion, which control the direction of locomotion by strengthening direct movement and/or inhibiting the opposite movement.

By using computational models, the researchers were able to describe these processes. Within the gel, there are regions where pulling forces predominate; pushing forces predominate in other areas. Variations in the intensity of the irradiation lead to different changes in the friction forces and the tensions in the gel. When these effects are added up, it is possible to predict in which direction a particular grid element of the gel will move.

One important finding from this model: special changes in the viscoelastic properties of the slime excreted by the snails and worms as they crawl are not required for locomotion, whether retrograde or direct.

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

Retrograde and Direct Wave Locomotion in a Photosensitive Self-Oscillating Gel by Lin Ren, Weibing She, Prof. Dr. Qingyu Gao, Dr. Changwei Pan, Dr. Chen Ji, and Prof. Dr. Irving R. Epstein. Angewandte Chemie International Edition DOI: 10.1002/anie.201608367 Version of Record online: 13 OCT 2016

© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

For anyone curious about the song, there’s this from its Wikipedia entry (Note: Links have been removed),

“The Loco-Motion” is a 1962 pop song written by American songwriters Gerry Goffin and Carole King. “The Loco-Motion” was originally written for Dee Dee Sharp but Sharp turned the song down.[1] The song is notable for appearing in the American Top 5 three times – each time in a different decade, performed by artists from three different cultures: originally African American pop singer Little Eva in 1962 (U.S. No. 1);[2] then American band Grand Funk Railroad in 1974 (U.S. No. 1);[3] and finally Australian singer Kylie Minogue in 1988 (U.S. No. 3).[4]

The song is a popular and enduring example of the dance-song genre: much of the lyrics are devoted to a description of the dance itself, usually done as a type of line dance. However, the song came before the dance.

“The Loco-Motion” was also the second song to reach No. 1 by two different musical acts. The earlier song to do this was “Go Away Little Girl”, also written by Goffin and King. It is one of only nine songs to achieve this

I had not realized this song had such a storied past; there’s a lot more about it in the Wikipedia entry.