Antennas can range from a few squiggles on a PCB to a gigantic Yagi on a tower. The basic laws of physics must be obeyed, though, and whatever form the antenna takes it all boils down to a conductor whose length resonates at a specific frequency. What works at one frequency is suboptimal at another, so an adjustable antenna would be a key component of a multi-band device. And a shape-shifting liquid metal antenna is just plain cool.
The first thing that pops into our head when we think of liquid metal is a silvery blob of mercury skittering inside the glass vial salvaged out of an old thermostat. The second image is a stern talking-to by the local HazMat team, so it’s probably best that North Carolina State University researchers [Michael Dickey] and [Jacob Adams] opted for gallium alloys for their experiments. Liquid at room temperature, these alloys have the useful property of oxidizing on contact with air and forming a skin. This allows the researchers to essentially extrude a conductor of any shape. What’s more, they can electrically manipulate the oxidative state of the metal and thereby the surface tension, allowing the conductor to change length on command. Bingo – an adjustable length antenna.
Radio frequency circuits aren’t the only application for gallium alloys. We’ve already seen liquid metal 3D printing with them. But we need to be careful, since controlling the surface tension of liquid metals might also bring us one step closer to this.
The theme of this year’s Hackaday Prize is to build something that matters, and there is nothing more important than water quality and pollution. Everything we eat and drink is influenced by the water quality in rivers and reservoirs. C4Derpillar, a semifinalist for the Hackaday Prize, is solving the problems of water-related health issues with innovative sensors for under $500 USD per unit.
The C4Derpiller is using capillary electrophoresis (CE) to detect anions and cations in waterways. CE pulls a water sample through a very thin tube with an electric current. As water is moving through this capillary, a sensor is able to detect heavy metals, pesticides, and other pollutants in a water supply. The team behind C4Derpiller has written a few posts about the separation chemistry of their device
Commercial CE equipment costs tens of thousands of dollars. The team behind the C4Derpillar are hoping to develop their pollution monitoring device and make it available for about $500 USD. That’s cheap enough for multiple pollution monitoring stations in the third world, and by pushing the results to the cloud, the C4Derpillar will be able to monitor pollution in real time.
You can check out C4Derpillar’s Hackaday Prize video below.
Continue reading “Hackaday Prize Semifinalist: Water Quality Monitoring”
Researchers from MIT and the Samsung Advanced Institute of Technology have been developing a new material that could potentially revolutionize the battery industry. A solid electrolyte that won’t wear out, lasting exponentially longer than current battery chemistry.
It also has the possibility to increase battery life, storage, and the safety of batteries — as liquid electrolytes are the main reason batteries catch on fire.
Sound too good to be true? The idea for solid-state batteries has been around for awhile, but it sounds like MIT and Samsung may have figured it out. The current materials used for solid electrolytes have difficulty conducting ions fast enough in order to be useful — but according to the researchers, they’ve discovered formula for the secret sauce. They’ve published their findings on Nature.com, which is sadly behind a pay wall.
Another great benefit of solid-state batteries is they would be able to operate at freezing temperatures without a problem. What do you think? Is Samsung blowing smoke, or will they actually release a battery you never have to replace?
Scientists at the George Washington University have managed to figure out a process in which they can literally grow carbon nanofibers out of thin air, using solar power.
Not only that, they do it using carbon dioxide — you know, that gas that contributes heavily to climate change? Using two electrodes, they pump power into a mixture of molten salt; lithium carbonate and lithium oxide. Then, carbon dioxide from the air reacts with the lithium oxide, producing carbon nanofibers — with more lithium carbonate and oxygen as byproducts.
The carbon nanofibers can then be used for a wide range of products or further processes. But beyond getting a useful material out of it, getting rid of carbon dioxide, if done on a large scale, could be beneficial for climate change. Unfortunately, they haven’t figured out how to do that just yet…
Continue reading “And For My Next Trick, I’ll Be Pulling Carbon Nanofibers out of Thin Air!”
Over in Italy, [Robotfactory] has a new setup called CopperFace that they claim allows you to essentially electroplate 3D printed objects with a metal coating using copper, nickel, silver, or gold.
We’ve talked about electroplating on plastic before, but that technique required mixing graphite and acetone. The CopperFace kit uses a conductive graphite spray and claims it deposits about 1 micron of plating on the object every two minutes.
We couldn’t help but wonder if the graphite spray is just the normal stuff used for lubricant. While the CopperFace’s electroplating tech seems pretty standard (copper sulfate and copper/phosphorus electrodes), we also wondered if some of the simpler copper acetate process we’ve covered before might be workable.
Continue reading “Metal 3D Printing with Your Printer”
Usually when Hackaday covers electroplating techniques, it’s to talk about through-hole PCB plating. But did you know you can use the same method to produce beautiful copper and silver crystal structures?
[Fred and Connie Libby] are kind enough to share how they make their crystals that they sell in tiny glass vials you can wear around your neck. The process is simple as you would think; it’s just an electrolyte solution, with a current passing through it, depositing the metal in an ion-exchange. Rather then stop once the part is sufficiently covered, you let the process run amok, and soon large crystal formations begin to emerge. [Fred and Connie] share their technique very briefly, so if you’re looking for a more detailed how-to guide, you can find one here.
Although silver crystals are a bit out of our budget, we wonder how large of a copper crystal could be grown? Large enough to be displayed on a coffee table? Surely such a work of art and science could be an interesting conservation piece in any hacker’s home.
Too much of a good thing can be a bad thing, and nitrate pollution due to agricultural fertilizer runoff is a major problem for both lakes and coastal waters. Assessing nitrate levels commercially is an expensive process that uses proprietary instruments and toxic reagents such as cadmium. But [Joshua Pearce] has recently developed an open-source photometer for nitrate field measurement that uses an enzyme from spinach and costs a mere $65USD to build.
The device itself is incredibly simple – a 3D printed enclosure houses an LED light source and a light sensor. The sample to be tested is mixed with a commercially available reagent kit based on the enzyme nitrate reductase, resulting in a characteristic color change proportional to the amount of nitrate present. The instrument reads the amount of light absorbed by the sample, and communicates the results to an Android device over a Bluetooth link.
Open-source instruments like this can really open up educational opportunities for STEM groups to get out into the real world and start making measurements that can make a difference. Not only can this enable citizen scientists and activists, but it also opens the door for getting farmers involved in controlling nitrate pollution at its source – knowing when a field has been fertilized enough can save a farmer unnecessary expense and reduce nitrate runoff.
There are a lot of other ways to put an open-source instrument like this to use in biohacking – photometery is a very common measuring modality in the life sciences, after all. We’ve seen similar instruments before, like a DIY spectrophotometer, or this 2015 Hackaday Prize entry medical tricorder with a built-in spectrophotometer. Still, for simplicity of build and potential impact, it’s hard to beat this instrument.