Tag Archives: Big Dog


It’s usually organ-on-a-chip or lab-on-a-chip or human-on-a-chip; this is my first tree-on-a-chip.

Engineers have designed a microfluidic device they call a “tree-on-a-chip,” which mimics the pumping mechanism of trees and other plants. Courtesy: MIT

From a March 20, 2017 news item on phys.org,

Trees and other plants, from towering redwoods to diminutive daisies, are nature’s hydraulic pumps. They are constantly pulling water up from their roots to the topmost leaves, and pumping sugars produced by their leaves back down to the roots. This constant stream of nutrients is shuttled through a system of tissues called xylem and phloem, which are packed together in woody, parallel conduits.

Now engineers at MIT [Massachusetts Institute of Technology] and their collaborators have designed a microfluidic device they call a “tree-on-a-chip,” which mimics the pumping mechanism of trees and plants. Like its natural counterparts, the chip operates passively, requiring no moving parts or external pumps. It is able to pump water and sugars through the chip at a steady flow rate for several days. The results are published this week in Nature Plants.

A March 20, 2017 MIT news release by Jennifer Chu, which originated the news item, describes the work in more detail,

Anette “Peko” Hosoi, professor and associate department head for operations in MIT’s Department of Mechanical Engineering, says the chip’s passive pumping may be leveraged as a simple hydraulic actuator for small robots. Engineers have found it difficult and expensive to make tiny, movable parts and pumps to power complex movements in small robots. The team’s new pumping mechanism may enable robots whose motions are propelled by inexpensive, sugar-powered pumps.

“The goal of this work is cheap complexity, like one sees in nature,” Hosoi says. “It’s easy to add another leaf or xylem channel in a tree. In small robotics, everything is hard, from manufacturing, to integration, to actuation. If we could make the building blocks that enable cheap complexity, that would be super exciting. I think these [microfluidic pumps] are a step in that direction.”

Hosoi’s co-authors on the paper are lead author Jean Comtet, a former graduate student in MIT’s Department of Mechanical Engineering; Kaare Jensen of the Technical University of Denmark; and Robert Turgeon and Abraham Stroock, both of Cornell University.

A hydraulic lift

The group’s tree-inspired work grew out of a project on hydraulic robots powered by pumping fluids. Hosoi was interested in designing hydraulic robots at the small scale, that could perform actions similar to much bigger robots like Boston Dynamic’s Big Dog, a four-legged, Saint Bernard-sized robot that runs and jumps over rough terrain, powered by hydraulic actuators.

“For small systems, it’s often expensive to manufacture tiny moving pieces,” Hosoi says. “So we thought, ‘What if we could make a small-scale hydraulic system that could generate large pressures, with no moving parts?’ And then we asked, ‘Does anything do this in nature?’ It turns out that trees do.”

The general understanding among biologists has been that water, propelled by surface tension, travels up a tree’s channels of xylem, then diffuses through a semipermeable membrane and down into channels of phloem that contain sugar and other nutrients.

The more sugar there is in the phloem, the more water flows from xylem to phloem to balance out the sugar-to-water gradient, in a passive process known as osmosis. The resulting water flow flushes nutrients down to the roots. Trees and plants are thought to maintain this pumping process as more water is drawn up from their roots.

“This simple model of xylem and phloem has been well-known for decades,” Hosoi says. “From a qualitative point of view, this makes sense. But when you actually run the numbers, you realize this simple model does not allow for steady flow.”

In fact, engineers have previously attempted to design tree-inspired microfluidic pumps, fabricating parts that mimic xylem and phloem. But they found that these designs quickly stopped pumping within minutes.

It was Hosoi’s student Comtet who identified a third essential part to a tree’s pumping system: its leaves, which produce sugars through photosynthesis. Comtet’s model includes this additional source of sugars that diffuse from the leaves into a plant’s phloem, increasing the sugar-to-water gradient, which in turn maintains a constant osmotic pressure, circulating water and nutrients continuously throughout a tree.

Running on sugar

With Comtet’s hypothesis in mind, Hosoi and her team designed their tree-on-a-chip, a microfluidic pump that mimics a tree’s xylem, phloem, and most importantly, its sugar-producing leaves.

To make the chip, the researchers sandwiched together two plastic slides, through which they drilled small channels to represent xylem and phloem. They filled the xylem channel with water, and the phloem channel with water and sugar, then separated the two slides with a semipermeable material to mimic the membrane between xylem and phloem. They placed another membrane over the slide containing the phloem channel, and set a sugar cube on top to represent the additional source of sugar diffusing from a tree’s leaves into the phloem. They hooked the chip up to a tube, which fed water from a tank into the chip.

With this simple setup, the chip was able to passively pump water from the tank through the chip and out into a beaker, at a constant flow rate for several days, as opposed to previous designs that only pumped for several minutes.

“As soon as we put this sugar source in, we had it running for days at a steady state,” Hosoi says. “That’s exactly what we need. We want a device we can actually put in a robot.”

Hosoi envisions that the tree-on-a-chip pump may be built into a small robot to produce hydraulically powered motions, without requiring active pumps or parts.

“If you design your robot in a smart way, you could absolutely stick a sugar cube on it and let it go,” Hosoi says.

This research was supported, in part, by the Defense Advance Research Projects Agency [DARPA].

This research’s funding connection to DARPA reminded me that MIT has an Institute of Soldier Nanotechnologies.

Getting back to the tree-on-a-chip, here’s a link to and a citation for the paper,

Passive phloem loading and long-distance transport in a synthetic tree-on-a-chip by Jean Comtet, Kaare H. Jensen, Robert Turgeon, Abraham D. Stroock & A. E. Hosoi. Nature Plants 3, Article number: 17032 (2017)  doi:10.1038/nplants.2017.32 Published online: 20 March 2017

This paper is behind a paywall.

Petman and lifelike movement

Thanks to the Nov. 7, 2011 posting on the Foresight Institute blog, I’ve found Petman,

Last month we noted the impressive progress achieved by Boston Dynamics’ AlphaDog project to develop a robot “pack animal” for the US military. Apparently there has been equally impressive progress in developing a humanoid robot capable of faithfully mimicking human movements to test protective suits for use by the military, and ultimately, to replace humans in a variety of arduous and dangerous tasks. This month IEEE Spectrum gave us this update: “Stunning Video of PETMAN Humanoid Robot From Boston Dynamics”, by Erico Guizzo.

I have written about Boston Dynamics and its military robots before, most recently about Big Dog in my Feb. 2, 2010 posting [scroll down a paragraph or two]. It’s amazing to see how much smoother the movement has become although I notice that the robot is tethered. From the Oct. 31, 2011 IEEE Spectrum article by Erico Guizzo,

It can walk, squat, kneel, and even do push-ups.

PETMAN is an adult-sized humanoid robot developed by Boston Dynamics, the robotics firm best known for the BigDog quadruped.

Today, the company is unveiling footage of the robot’s latest capabilities. It’s stunning.

The humanoid, which will certainly be compared to the Terminator Series 800 model, can perform various movements and maintain its balance much like a real person.

Boston Dynamics is building PETMAN, short for Protection Ensemble Test Mannequin, for the U.S. Army, which plans to use the robot to test chemical suits and other protective gear used by troops. It has to be capable of moving just like a soldier — walking, running, bending, reaching, army crawling — to test the suit’s durability in a full range of motion.

Marc Raibert, the founder and president of Boston Dynamics, tells me that the biggest challenge was to engineer the robot, which uses a hydraulic actuation system, to have the approximate size of a person. “There was a great deal of mechanical design we had to do to get everything to fit,” he says.

The Guizzo article features a number of images and a video demonstrating Petman’s abilities along with more details about the robot’s full capabilities. I went on YouTube to find this Petman mashup,

The Japanese have featured some robots that look like and dance like people as I noted in my Oct. 18, 2010 posting where I also discussed the ‘uncanny valley’ in relationship to those robots. Keeping on the ‘humanoid’ robot theme, I also posted about Geminoid robots in the context of a Danish philosopher who commissioned, for a philosophy project, a Geminoid that looked like himself and whose facial features are expressive. In that same posting, March 10, 2011, I wrote about some work at the Georgia Institute of Technology (US) where they too are developing robots that move like humans. The March 2011 posting features more information about the ‘uncanny valley’, including a diagram.

I wonder what it will be like to encounter one of these humanoid robots in the flesh as it were.

nanoBIDS; military robots from prototype to working model; prosthetics, the wave of the future?

The Nanowerk website is expanding. From their news item,

Nanowerk, the leading information provider for all areas of nanotechnologies, today added to its nanotechnology information portal a new free service for buyers and vendors of micro- and nanotechnology equipment and services. The new application, called nanoBIDS, is now available on the Nanowerk website. nanoBIDS facilitates the public posting of Requests for Proposal (RFPs) for equipment and services from procurement departments in the micro- and nanotechnologies community. nanoBIDS is open to all research organizations and companies.

I checked out the nanoBIDS page and found RFP listings from UK, US (mostly), and Germany. The earliest are dated Jan.25, 2010 so this site is just over a week old and already has two pages.

The Big Dog robot (which I posted about briefly here) is in the news again. Kit Eaton (Fast Company) whose article last October first alerted me to this device now writes that the robot is being put into production. From the article (Robocalypse Alert: Defense Contract Awarded to Scary BigDog),

The contract’s been won by maker Boston Dynamics, which has just 30 months to turn the research prototype machines into a genuine load-toting, four-legged, semi-intelligent war robot–“first walk-out” of the newly-designated LS3 is scheduled in 2012.

LS3 stands for Legged Squad Support System, and that pretty much sums up what the device is all about: It’s a semi-autonomous assistant designed to follow soldiers and Marines across the battlefield, carrying up to 400 pounds of gear and enough fuel to keep it going for 24 hours over a march of 20 miles.

They have included a video of the prototype on a beach in Thailand and as Eaton notes, the robot is “disarmingly ‘cute'” and, to me, its legs look almost human-shaped, which leads me to my next bit.

I found another article on prosthetics this morning and it’s a very good one. Written by Paul Hochman for Fast Company, Bionic Legs, iLimbs, and Other Super-Human Prostheses delves further into the world where people may be willing to trade a healthy limb for a prosthetic. From the article,

There are many advantages to having your leg amputated.

Pedicure costs drop 50% overnight. A pair of socks lasts twice as long. But Hugh Herr, the director of the Biomechatronics Group at the MIT Media Lab, goes a step further. “It’s actually unfair,” Herr says about amputees’ advantages over the able-bodied. “As tech advancements in prosthetics come along, amputees can exploit those improvements. They can get upgrades. A person with a natural body can’t.”

I came across both a milder version of this sentiment and a more targeted version (able-bodied athletes worried about double amputee Oscar Pistorius’ bid to run in the Olympics rather than the Paralympics) when I wrote my four part series on human enhancement (July 22, 23, 24 & 27, 2009).

The Hochman article also goes on to discuss some of the aesthetic considerations (which I discussed in the same posting where I mentioned the BigDog robots). What Hochman does particularly well is bringing all this information together and explaining how the lure of big money (profit) is stimulating market development,

Not surprisingly, the money is following the market. MIT’s Herr cofounded a company called iWalk, which has received $10 million in venture financing to develop the PowerFoot One — what the company calls the “world’s first actively powered prosthetic ankle and foot.” Meanwhile, the Department of Veterans Affairs recently gave Brown University’s Center for Restorative and Regenerative Medicine a $7 million round of funding, on top of the $7.2 million it provided in 2004. And the Defense Advanced Research Projects Administration (DARPA) has funded Manchester, New Hampshire-based DEKA Research, which is developing the Luke, a powered prosthetic arm (named after Luke Skywalker, whose hand is hacked off by his father, Darth Vader).

This influx of R&D cash, combined with breakthroughs in materials science and processor speed, has had a striking visual and social result: an emblem of hurt and loss has become a paradigm of the sleek, modern, and powerful. Which is why Michael Bailey, a 24-year-old student in Duluth, Georgia, is looking forward to the day when he can amputate the last two fingers on his left hand.

“I don’t think I would have said this if it had never happened,” says Bailey, referring to the accident that tore off his pinkie, ring, and middle fingers. “But I told Touch Bionics I’d cut the rest of my hand off if I could make all five of my fingers robotic.”

This kind of thinking is influencing surgery such that patients are asking to have more of their bodies removed.

The article is lengthy (by internet standards) and worthwhile as it contains nuggets such as this,

But Bailey is most surprised by his own reaction. “When I’m wearing it, I do feel different: I feel stronger. As weird as that sounds, having a piece of machinery incorporated into your body, as a part of you, well, it makes you feel above human. It’s a very powerful thing.”

So the prosthetic makes him “feel above human,” interesting, eh? It leads to the next question (and a grand and philosophical one it is), what does it mean to be human? At least lately, I tend to explore that question by reading fiction.

I have been intrigued by Catherine Asaro‘s Skolian Empire series of books. The series features human beings (mostly soldiers) who have something she calls ‘biomech’  in their bodies to make them smarter, stronger, and faster. She also populates worlds with people who’ve had (thousands of years before) extensive genetic manipulation so they can better adapt to their new homeworlds. Her characters represent different opinions about the ‘biomech’ which is surgically implanted usually in adulthood and voluntarily. Asaro is a physicist who writes ‘hard’ science fiction laced with romance. She handles a great many thorny social questions in the context of this Skolian Empire that she has created where the technologies (nano, genetic engineering, etc.)  that we are exploring are a daily reality.

Happy T Day! Robots; Nano-enabled prosthetics; ISEA 2009 aesthetics and prosthetics; Global TV (national edition): part 2

Happy Thanksgiving to everyone as Canada celebrates.

Since I have mentioned military robots in the not too distant past, this recent headline Two Military Robots That Rival the Creepiest Sci-Fi Creatures for Kit Eaton’s Fast Company article caught my eye. One of the robots, Big Dog (and its companion prototype Small Dog), utilizes artificial intelligence to navigate terrain and assist soldiers in the field. The larger one can carry heavy loads while the smaller one could be used for reconnaissance. The other robot is a cyborg beetle. Electrodes have been implanted so the beetle’s flight patterns can be controlled. There are two videos, one for each robot. It is a very disconcerting experience watching the beetle being flown by someone standing in front of a set of controls.

Keeping with the theme of planting electrodes, I found something on Azonano about a bio- adaptive prosthetic hand. Funded by the European Union as a nanotechnology project, here’s more from the news item,

What is unique about the sophisticated prototype artificial hand developed by the SMARTHAND partners is that not only does it replicate the movements of a real hand, but it also gives the user sensations of touch and feeling. The researchers said the hand has 4 electric motors and 40 sensors that are activated when pressed against an object. These sensors stimulate the arm’s nerves to activate a part in the brain that enables patients to feel the objects.

Led by Sweden’s Lund University, the researchers continue to work on the sensory feedback system within the robotic hand. The hurdle they need to cross is to make the cables and electric motors smaller. Nanotechnology could help the team iron out any problems. Specifically, they would implant a tiny processing unit, a power source and a trans-skin communication method into the user of the hand to optimise functionality.

It’s a fascinating read which brought to mind an ISEA (International Symposium on Electronic Arts) 2009 presentation by Dr. Lanfranco Aceti (professor at Sabanci University in Istanbul, Turkey). Titled The Aesthetic Beauty of the Artificial: When Prosthetic Bodies Become an Art Expression of Empowering Design Technologies, the presentation was a revelation. Dr. Aceti’s research yielded a rather surprising insight from a doctor in London, England who specializes in prosthetics. According to the doctor, women want limbs that most closely resemble their original but men (under 50 years old usually) want limbs that are metallic and/or look high tech. Lanfranco suggested that the men have been influenced by movies. Take for example, Wolverine (Wikipedia entry here) where the hero’s skeleton has been reinforced with metal and he can make his claws (now covered with metal) protrude from his arms at will. You can view Lanfranco’s site here or a simple biography about him here.

A few months back I posted about  prosthetics and design student projects and I’m starting to sense a trend emerging from these bits and pieces of information. There is the repair aspect to prosthetics but there is also an increasing interest not just in the aesthetics but in the notion of improving on the original. At its most extreme, I can imagine people wanting to remove perfectly healthy limbs and organs to get an improved version.

I got a chance to see part 2 of Global TV’s (broadcast in Canada) nanotechnology series, Small Wonders. As I’ve noticed that my link for part 1 of the series is no longer useful I am providing a link to part 2 which will land you on the search page. If you don’t see part 2 listed, go to the mutimedia tab which is just above the search results and where you can find part 1 and I assume, at some point, part 2.

As I hoped, they focused on nanotechnology projects in the materials field in part 2 of the series. They noted that nanotechnology-based materials in sports equipment and clothing are already available in the market place. An interview with Dr. Robert Wolkow at the National Institute of Nanotechnology and at the Physics Dept. at the University of Alberta, featured a discussion about replacing silicon chips with more efficient materials built at the molecular level.