Miniature Robotics

[Recusant]

I read up about it on Wikipedia, and according to the article, the "RoBeetle" described below would qualify as a minirobot, I think. The new methanol-powered muscles sound like a real development--if they can figure out some way to provide electrical power to run electronics for a control mechanism, interesting possibilities open up. I'm thinking miniaturized piezoelectrical systems, maybe. 

"Beyond batteries: Scientists build methanol-powered beetle bot" | TechXplore

The RoBeetle. Image credit: Yang et al., Science Robotics

Scientists have long envisioned building tiny robots capable of navigating environments that are inaccessible or too dangerous for humans—but finding ways to keep them powered and moving has been impossible to achieve.

A team at the University of Southern California has now made a breakthrough, building an 88-milligram (one three hundredth of an ounce) "RoBeetle" that runs on methanol and uses an artificial muscle system to crawl, climb and carry loads on its back for up to two hours.

It is just 15 millimeters (.6 inches) in length, making it "one of the lightest and smallest autonomous robots ever created," its inventor Xiufeng Yang told AFP.

"We wanted to create a robot that has a weight and size comparable to real insects," added Yang, who was lead author of a paper describing the work in Science Robotics on Wednesday.

The problem is that most robots need motors that are themselves bulky and require electricity, which in turn makes batteries necessary.

The smallest batteries available weigh 10-20 times more than a tiger beetle, a 50 milligram insect the team used as their reference point.

To overcome this, Yang and his colleagues engineered an artificial muscle system based on liquid fuel—in this case methanol, which stores about 10 times more energy than a battery of the same mass.

[Continues . . .]

The paper is open access:

"An 88-milligram insect-scale autonomous crawling robot driven by a catalytic artificial muscle" | Science Robotics

Abstact:

The creation of autonomous subgram microrobots capable of complex behaviors remains a grand challenge in robotics largely due to the lack of microactuators with high work densities and capable of using power sources with specific energies comparable to that of animal fat (38 megajoules per kilogram). Presently, the vast majority of microrobots are driven by electrically powered actuators; consequently, because of the low specific energies of batteries at small scales (below 1.8 megajoules per kilogram), almost all the subgram mobile robots capable of sustained operation remain tethered to external power sources through cables or electromagnetic fields. Here, we present RoBeetle, an 88-milligram insect-sized autonomous crawling robot powered by the catalytic combustion of methanol, a fuel with high specific energy (20 megajoules per kilogram). The design and physical realization of RoBeetle is the result of combining the notion of controllable NiTi-Pt–based catalytic artificial micromuscle with that of integrated millimeter-scale mechanical control mechanism (MCM). Through tethered experiments on several robotic prototypes and system characterization of the thermomechanical properties of their driving artificial muscles, we obtained the design parameters for the MCM that enabled RoBeetle to achieve autonomous crawling. To evaluate the functionality and performance of the robot, we conducted a series of locomotion tests: crawling under two different atmospheric conditions and on surfaces with different levels of roughness, climbing of inclines with different slopes, transportation of payloads, and outdoor locomotion.

[Randy]

This is a fascinating article, Recusant. I've been interested in robots since I was a kid.

About twenty years ago, give or take, I played around with Mindstorms robotics sets. I was an old kid, what can I say? I enjoyed the hour or so I'd spend each day when my wife was doing something else. On weekends, when we weren't traveling I'd spend a little longer on them.

I read what was in the quote and now I'm going to read the rest of it.

[Tank]

100 years from now...

[xSilverPhinx]

The RoBeetle. Image credit: Yang et al., Science Robotics

Cute!

[Recusant]

Note that in the television show Futurama the robot character Bender B. Rodriguez runs on alcohol, though he prefers ethanol rather than methanol. 

[Tank]

I love Bender 

[Recusant]

I love Bender 

It could be said that he's actually the central character of the series. Fry is more his sidekick than the other way around. 

The new methanol-powered muscles sound like a real development--if they can figure out some way to provide electrical power to run electronics for a control mechanism, interesting possibilities open up. I'm thinking miniaturized piezoelectrical systems, maybe. 

This one kept buzzing around in my head, so I did some looking around and found a paper on extremely small scale piezoelectrical "energy harvesters." The concept is being developed, and the possibility of battery-free electronic control systems for micro-scale alcohol-powered robots seems less far-fetched. On the other hand, I'm not qualified to evaluate the paper, and it's published in a pay to publish journal.

"Effects of Proof Mass Geometry on Piezoelectric Vibration Energy Harvesters" | sensor

Abstract:

Piezoelectric energy harvesters have proven to have the potential to be a power source in a wide range of applications. As the harvester dimensions scale down, the resonance frequencies of these devices increase drastically. Proof masses are essential in micro-scale devices in order to decrease the resonance frequency and increase the strain along the beam to increase the output power. In this work, the effects of proof mass geometry on piezoelectric energy harvesters are studied. Different geometrical dimension ratios have significant impact on the resonance frequency, e.g., beam to mass lengths, and beam to mass widths. A piezoelectric energy harvester has been fabricated and tested operating at a frequency of about 4 kHz within the audible range. The responses of various prototypes were studied, and an optimized T-shaped piezoelectric vibration energy harvester design is presented for improved performance.

[Recusant]

Proof of concept on a microrobot--powered remotely by laser light.

"Laser jolts microscopic electronic robots into motion" | Cornell Chronicle

A Cornell-led collaboration has created the first microscopic robots that incorporate semiconductor components, allowing them to be controlled – and made to walk – with standard electronic signals.

These robots, roughly the size of paramecium, provide a template for building even more complex versions that utilize silicon-based intelligence, can be mass produced, and may someday travel through human tissue and blood.

The collaboration is led by Itai Cohen, professor of physics, Paul McEuen, the John A. Newman Professor of Physical Science – both in the College of Arts and Sciences – and their former postdoctoral researcher Marc Miskin, who is now an assistant professor at the University of Pennsylvania.

[. . .]

The walking robots are the latest iteration, and in many ways an evolution, of Cohen and McEuen's previous nanoscale creations, from microscopic sensors to graphene-based origami machines.

The new robots are about 5 microns thick (a micron is one-millionth of a meter), 40 microns wide and range from 40 to 70 microns in length. Each bot consists of a simple circuit made from silicon photovoltaics – which essentially functions as the torso and brain – and four electrochemical actuators that function as legs.

[Continues . . .]

The paper is behind a paywall.

Abstract:

Fifty years of Moore's law scaling in microelectronics have brought remarkable opportunities for the rapidly evolving field of microscopic robotics. Electronic, magnetic and optical systems now offer an unprecedented combination of complexity, small size and low cost6,7, and could be readily appropriated for robots that are smaller than the resolution limit of human vision (less than a hundred micrometres). However, a major roadblock exists: there is no micrometre-scale actuator system that seamlessly integrates with semiconductor processing and responds to standard electronic control signals. Here we overcome this barrier by developing a new class of voltage-controllable electrochemical actuators that operate at low voltages (200 microvolts), low power (10 nanowatts) and are completely compatible with silicon processing. To demonstrate their potential, we develop lithographic fabrication-and-release protocols to prototype sub-hundred-micrometre walking robots. Every step in this process is performed in parallel, allowing us to produce over one million robots per four-inch wafer. These results are an important advance towards mass-manufactured, silicon-based, functional robots that are too small to be resolved by the naked eye.

[Recusant]

Microrobots used to connect neural networks. This could eventually be a means of repairing nerve damage.

"Microrobots used to build bridge between rat nerve cell networks" | Medical Xpress

A team of researchers affiliated with several institutions in South Korea has created microrobots that are able to serve as bridge builders between rat nerve cell networks. In their paper published in the journal Science Advances, the group describes how their microrobots were constructed and how well they served as a bridge builder between neural networks.

Scientists have taken many approaches to study of the brain. One way is to try to grow a brain from nerve cells. Prior work has shown that it is possible to grow a network of neural cells on a glass plate Such a network is, of course, 2-D. In this new effort, the researchers have taken a step toward the creation of a 3-D neural network by devising a way to connect 2-D neural networks using microrobots.

The work consisted of creating rectangular microrobots (300 micrometers long and 95 micrometers wide) out of a polymer coated with nickel and titanium. The movement of the microrobot was controlled by applying external magnetic fields. To make use of such robots, the researchers first grew two separate neural networks on a plate of glass just 300 micrometers apart. Next, they grew another neural network on the surface of the microrobot. Once all the networks were grown and in place, the researchers applied a magnetic field to the robot to push it into place between the other two neural networks. Another magnetic field was used to fine-tune the position of the microrobot relative to the two networks. And then the researchers simply waited and watched as events unfolded. They found that not only did nerve cells grow from either end of the microrobot toward the other neural networks, but the other networks began reaching out to the network on the microrobot. Over time, a bridge formed between the two original neural networks. The researchers found that when they applied a slight charge to one of the original networks, it was carried across the bridge to the other network, proving that it worked as intended.

[Continues . . .[/color]]

The paper is open access.

"A magnetically actuated microrobot for targeted neural cell delivery and selective connection of neural networks" | ScienceAdvances

Abstract:

There has been a great deal of interest in the development of technologies for actively manipulating neural networks in vitro, providing natural but simplified environments in a highly reproducible manner in which to study brain function and related diseases. Platforms for these in vitro neural networks require precise and selective neural connections at the target location, with minimal external influences, and measurement of neural activity to determine how neurons communicate. Here, we report a neuron-loaded microrobot for selective connection of neural networks via precise delivery to a gap between two neural clusters by an external magnetic field. In addition, the extracellular action potential was propagated from one cluster to the other through the neurons on the microrobot. The proposed technique shows the potential for use in experiments to understand how neurons communicate in the neural network by actively connecting neural clusters.

[Icarus]

^Scary stuff!