Renewable Hydrogen Sucked From Thinish Air

Stored hydrogen is often touted as the ultimate green energy solution, provided the hydrogen is produced from genuinely green power sources. But there are technical problems to be overcome before your average house will be heated with pumped or tank-stored hydrogen. One problem is that the locations that have lots of scope for renewable energy, don’t always have access to plenty of pure water, and for electrolysis you do need both. A team from Melbourne University have come up with a interesting way to produce hydrogen by electrolysis directly from the air.

Redder areas have more water risk and renewable potential

By utilising a novel electrolysis cell with a hygroscopic electrolyte, the so-called direct air electrolysis (DAE) can operate with humidity as low as 4% relative, so perfectly fine even in the most arid areas, after all there may not be clouds but the air still holds a bit of water. This is particularly relevant to regions of the world, such as deserts, where there is simultaneously a high degree of water risk, and plenty of solar potential. Direct electrolysis of saline extracted at coastal areas is one option, but dealing with the liberated chlorine is a big problem.

The new prototype is very simple in construction, with a sponge of melamine or a sintered glass foam soaked in a compatible electrolyte. Potassium Hydroxide (alkaline) was tried as was Potassium Acetate (base) and Sulphuric Acid, but the latter degraded the host material in a short time. Who would have imagined? Anyway, with electrolysis cell design, a key problem is ensuring the separate gasses stay separate, and in this case, are also separate from the air. This was neatly ensured by arranging the electrolyte sponge fully covered both electrodes, so as the hygroscopic material extracted water from the air, the micro-channels in the structure filled up with liquid, with it touching both ends of the cell, forming the circuit and allowing the electrolysis to proceed.

Hydrogen, being very light, would rise upward through holes in the cathode, to be collected and stored. Oxygen simply passed back into the air, after passing though the liquid reservoir at the base. Super simple, and from reading the paper, quite effective too.

You can kind of imagine a future built around this now, where you’re driving your hydrogen fuel cell powered dune buggy around the Sahara one weekend, and you stop at a solar-powered hydrogen fuel station for a top up and a pasty. Ok, possibly not that last bit.

The promised hydrogen economy may be inching closer. We covered using aluminium nanoparticles to rip hydrogen out of water. But once you have the gas, you need to store and handle it. Toyota might have a plan for that. Then perhaps handling gas directly at all isn’t a great idea, and maybe the future is paste?

Thanks to [MmmDee] for the tip!

The Benefits Of Displacement Ventilation

The world has been shaken to its core by a respiratory virus pandemic. Humanity has been raiding the toolbox for every possible weapon in the fight, whether that be masks, vaccinations, or advanced antiviral treatments.

As far as medicine has come in tackling COVID-19 in the past two years, the ultimate solution would be to cut the number of people exposed to the pathogen in the first place. Improving our ventilation methods may just be a great way to cut down on the spread. After all, it’s what they did in the wake of the Spanish Flu.

Continue reading “The Benefits Of Displacement Ventilation”

SYPHCOM, the compact CO2 sensor

Compact Sensor Keeps You Safe By Watching CO2 Levels

Remember when work meetings were just a bunch of people filling up a small, poorly ventilated room with their exhaled breath? Back in the good old days, all you had to worry about was being lulled to sleep by a combination of the endless slide deck and the accumulation of carbon dioxide. Now? Well, the stakes may just be a little bit higher.

In either situation, knowing the CO2 level in a room could be a handy data point, which is where a portable CO2 sensor like this one could be useful. Or at least that’s [KaRMaN]’s justification for SYPHCOM, the “simple yet powerful handheld carbon dioxide meter.” The guts of the sensor are pretty much what you’d expect — an Arduino Pro Micro, a SenseAir S8 CO2 sensor board, and the necessary battery and charging circuits. But the build does break the mold in a couple of interesting places. One is in the choice of display — a 1980s-era LED matrix display. The HDSP2000 looks like it belongs in a nice bench meter, and is surprisingly legible without a filter. It looks like it flickers a bit in the video below, but chances are that’s just a camera artifact.

The other nice part of this build is the obvious care [KaRMaN] put into making it as small as possible. The layout of boards and components is very clever, making this a solid, compact package, even without an enclosure. We’ve seen CO2 sensors with more features, but for a quick check on air quality, SYPHCOM looks like a great tool.

Continue reading “Compact Sensor Keeps You Safe By Watching CO2 Levels”

A Nerf Gun Upgrade

A lot of us have nostalgia for our childhood toys, and as long as they’re not something like lawn darts that nostalgia often leads to fun upgrades since some of us are adults with industrial-sized air compressors. Classics like Super Soakers and Nerf guns are especially popular targets for improvements, and this Nerf machine gun from [Emiel] is no exception.

The build takes a Nerf ball-firing toy weapon and basically tosses it all out of the window in favor of a custom Nerf ball launching rifle. He starts with the lower receiver and machines a pneumatic mechanism that both loads a ball into the chamber and then launches it. This allows the rifle to be used in both single-shot mode and also in fully-automatic mode. From there, a barrel is fashioned along with the stock and other finishing touches.

[Emiel] also uses a high-speed camera to determine the speed of his new Nerf gun but unfortunately it isn’t high-speed enough, suffering from the same fate as one of the fastest man-made objects ever made, and he only has a lower bound on the speed at 400 km/h. If you don’t want to go fast with your Nerf builds, though, perhaps you should build something enormous instead. Continue reading “A Nerf Gun Upgrade”

Bad Idea For Desoldering Actually Might Be Pretty Smart

This video on building a DIY desoldering iron says it all right up front: this is stupid and dangerous, and you shouldn’t do it. But that doesn’t mean it doesn’t work, or that it doesn’t have potential to be turned into something else.

The story begins, as it often does these days, on the pages of Amazon as [AnotherMaker] shopped for a real desoldering setup. Despite a case of sticker shock, he took the plunge on a nice Hakko vacuum desolderer, but as is also often the case, it failed to arrive. Rather than accept defeat, [AnotherMaker] purchased a cheap-o soldering iron and a brass tee fitting for small-bore tubing that would chuck nicely into the spot where the stock tip once lived, giving him a way to both melt solder and move air.

Unfortunately, rather than applying a vacuum, he chose to blast 100 PSI compressed air through the tip, which certainly moves a lot of solder, perhaps at the cost of burns and eye injuries. The potential for accidental short circuits is pretty high too, but c’mon — it’s not like we all haven’t flicked or dropped a board to desolder something. Is this really much different?

As fraught with peril as this method may be, [AnotherMaker] is onto something here. Perhaps adding a 3D-printed venturi generator could turn that blast of air into a vacuum. Or maybe a vacuum pump for a manual pick-and-place would do the trick too.

Continue reading “Bad Idea For Desoldering Actually Might Be Pretty Smart”

Obstacle Avoidance For Drones, Learned From Mosquitoes

Our understanding of the sensory capabilities of animals has a lot of blanks, and often new discoveries serve as inspiration for new technology. Researchers from the University of Leeds and the Royal Veterinary College have found that mosquitos can navigate in complete darkness by detecting the subtle changes in the air flow created when they fly close to obstacles. They then used this knowledge to build a simple but effective sensor for use on drones.

Extremely sensitive receptors at the base of the antennae on mosquitoes’ heads, called the Johnston’s organ, allow them to sense these tiny changes in airflow. Using fluid dynamics simulations based on high speed photography, the researchers found that the largest changes in airflow occur over the mosquito’s head, which means the receptors are in exactly the right place. From their data, scientists predict that mosquitos could possibly detect surfaces at a distance of more than 20 wing lengths. Considering how far 20 arm lengths is for us, that’s pretty impressive. If you can get past the paywall, you can read the full article from the Science journal.

Using their newfound knowledge, the researchers equipped a small drone with probe tubes connected to differential pressure sensors. Using these sensors the drone was able to effectively detect when it got close to the wall or floor, and avoid a collision. The sensors also require very little computational power because it’s only a basic threshold value. Check out the video after the break.

Although this sensing method might not replace ultrasonic or time-of-flight sensors for drones, it does show that there is still a lot we can learn from nature, and that simpler is usually better. We’ve already seen simple insect-inspired navigation for drone swarms, as well as an optical navigation device for humans that works without satellites and only requires a view of the sky. Thanks for the tip [Qes]! Continue reading “Obstacle Avoidance For Drones, Learned From Mosquitoes”

Soft Rotating Pneumatic Actuators

When we think of pneumatic actuators, we typically consider the standard varieties of pneumatic cylinder, capable of linear motion. These can be referred to as “hard” actuators, made of rigid components and capable of great accuracy and force delivery. However, “soft” actuators have their own complementary abilities – such as being able to handle more delicate tasks and being less likely to injure human operators when used in collaborative operations. The Whitesides Research Group at Harvard University has undertaken significant research in this field, and released a paper covering a novel type of soft pneumatic actuator.

The actuator consists of a series of soft, flexible sealed chambers which surround a wooden dowel in the center. By applying vacuum to these various chambers, the dowel in the center can be pulled into up to eight different positions. It’s a unique concept, and one we can imagine could have applications in various material processing scenarios.

The actuator was built by moulding elastomers around 3D printed components, so this is a build that could theoretically be tackled by the DIYer. The paper goes into great detail to quantify the performance of the actuator, and workshops several potential applications. Testing is done on a fluid delivery and stirring system, and a tethered robotic walker was built. The team uses the term cVAMS – cyclical vacuum actuated machine – to describe the actuator technology.

The world of soft robotics is a hot bed of development, and we look forward to further work in this field. It’s not just Harvard, either – we’ve seen interesting work from Yale¬†and from the Hackaday community too!