Self-assembling Polymers Support Silicone 3D Prints

We all know what the ultimate goal of 3D printing is: to be able to print parts for everything, including our own bodies. To achieve that potential, we need better ways to print soft materials, and that means we need better ways to support prints while they’re in progress.

That’s the focus of an academic paper looking at printing silicone within oil-based microgels. Lead author [Christopher S. O’Bryan] and team from the Soft Matter Research Lab at the University of Florida Gainesville have developed a method using self-assembling polymers soaked in mineral oil as a matrix into which silicone elastomers can be printed. The technique takes advantage of granular microgels that are “jammed” into a solid despite being up to 95% solvent. Under stress, such as that exerted by the nozzle of a 3D printer, the solid unjams into a flowing liquid, allowing the printer to extrude silicone. The microgel instantly jams back into a solid again, supporting the silicone as it cures.

[O’Bryan] et al have used the technique to print a model trachea, a small manifold, and a pump with ball valves. There are Quicktime videos of the finished manifold and pump in action. While we’ve covered flexible printing options before, this technique is a step beyond and something we’re keen to see make it into the hobby printing market.

[LonC], thanks for the tip.

Simple and Effective Car Lock Jammer Detector

[Andrew Nohawk], has noticed a spike of car break-ins and thefts — even in broad daylight — in his native South Africa. The thieves have been using remote jammers. Commercial detectors are available but run into the hundreds of dollars. He decided to experiment with his own rig, whipping up a remote jamming ‘detector’ for less than the cost of a modest meal.

Operating on the principle that most remote locks work at 433MHz, [Nohawk] describes how criminals ‘jam’ the frequency by holding down the lock button on another device, hoping to distort or outright interrupt the car from receiving the signal to lock the doors. [Nohawk] picked up a cheap 433MHz receiver (bundled with a transceiver), tossed it on a breadboard with an LED connected to the data channel of the chip on a 5V circuit, and voila — whenever the chip detects activity on that frequency, the LED lights up. If you see sustained activity on the band, there’s a chance somebody nearby might be waiting for you to leave your vehicle unattended.

If you want to know more about how these jamming attacks work, check out [Samy Kamkar’s] talk from the Hackaday SuperConference.

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Jamming WiFi by Jumping on the ACK

As we fill our airwaves with more and more wirelessly connected devices the question of what could disrupt this systems becomes more and more important. Here’s a particularly interesting example because the proof of concept shows that you don’t need specialized hardware to pull it off. [Bastian Bloessl] found an interesting tweak to previous research that allows an Atheros WiFi card to jam WiFi by obscuring ACK frames.

The WiFi protocol specifies an Acknowledgement Frame (ACK) which is sent by the receiving device after error correction has been performed. It basically says: “yep, I got that data frame and it checks out”. This error correcting process turns out to be the key to [Bastian’s] technique as it provides time for the attack hardware to decide if it’s going to jam the ACK or not.

The jamming technique presented by [Mathy Vanhoef] at the end 2014 outlined both constant and selective jamming. The selective part involved listening for data packets and analyzing them to determine if they are headed to a MAC the attacker wishes to jam. The problem is that by the time your commodity hardware has decoded that address it’s too late to jam the packet. [Bastian] isn’t trying to jam the data frame, he’s jamming the ACK that the receiver sends back. Without that acknowledgement, the sender will not transmit any new data frames as it assumes there is a problem on the receiving end.

Anti-Drone Fence: Science or Snakeoil?

Remember when it was laser pointers? Well, now it’s drones.

[Thinkerer] sent us this link to what’s essentially a press release for a company called Sensofusion that makes a UAV detector and (they claim) smart jammer, and apparently one is being installed at Denver International airport.

We buy that the “Airfence” system will be able to detect known systems by signature, and possibly even take them over. We’ve seen two exploits of quadcopter radio protocols (one a timing attack and the other a controller ID spoof) that would allow them to do just that. But is that the problem? Don’t most of the major manufacturers fence off airports in software these days anyway? And are drones really the droids that you’re looking for?

They also make some claims about being able to detect and stop DIY copters, but we don’t see how. Imagine that your copter ran encrypted on 2.4 GHz. How is this different from any other WiFi signal? Or imagine that it sends and receives infrequent data in the congested pager bands? And short of jamming, we don’t see how they’re going to take down anything that they don’t already understand.

So, commenteers, how would you do it? Detect and even take over an arbitrary drone? Possible or snakeoil?

Retrotechtacular: Radar Jamming

It’s been said that the best defense is a good offense. When aloft and en route to deliver a harmful payload to the enemy, the best defense is to plan your approach and your exit carefully, and to interfere with their methods of detection. If they can’t find you, they can’t shoot you.

As of May 1962, the United States military was using three major classifications of radar jamming technology as described in this week’s film: the AN/ALQ-35 multiple target repeater, the AN/ALQ-55 communications link disrupter, and the AN/ALQ-41 and -51 track breakers. The most important role of these pieces of equipment is to buy time, a precious resource in all kinds of warfare.

The AN/ALQ-35 target repeater consists of a tuner, pulse generator, transmitter, and control panel working in concert to display multiple false positives on the enemy’s PPI scopes. The unit receives the incoming enemy pulse, amplifies it greatly, repeats it, and sends them back with random delays.

The AN/ALQ-55 comm disrupter operates in the 100-210MHz band. It distinguishes the threatening enemy communication bands from those of beacons and civilians, evaluates them, and jams them with a signal that’s non-continuous, which helps avoid detection.

Finally, the AN/ALQ-41 and -51 track breakers are designed to break enemy lock-on and to give false information. It provides simultaneous protection against pulse ranging, FM-CW, conical, and monopulse radar in different ways, based on each method’s angle and range.

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Jamming Robot will Destroy You at Beer Pong

DSC_0363Wandering the aisles of Eureka Park, the startup area of the Consumer Electronics Show, I spotted a mob of people and sauntered over to see what the excitement was all about. Peeking over this gentleman’s shoulder I realized he was getting spanked at Beer Pong… by a robot!

Those in the know will recognize that the bot has only 3 cups left and so the guy definitely was giving it run for its money. But the bot’s ability to swish the ball on nearly every throw accounts for the scoreboard which read Robot: 116, Humans: 11. Unlike the ping pong robot hoax from last March, we can vouch for this one being real!

If you’re trying to attract the geek demographic, this must be one of the best offerings ever shown at a trade show. Empire Robotics manufactures the VERSABALL gripper. We know this as a jamming gripper and have been looking at the tech progress for many years now. Looking back to this Cornell research video from 2010 we realize it is based on the white paper which [John Amend, PhD] co-authored. He’s now CTO and Co-Founder of the company and was one of the people running the booth. We love it when trade show booths are staffed by the engineers!

Join me after the break for a rundown of how the system works along with a video clip of it hitting the target.

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Dead simple jamming gripper design

dead-simple-jamming-gripper

This jamming gripper design is the simplest we’ve seen so far. It uses a syringe to generate the suction necessary for the orange appendage to grip an object.

As with previous offerings this uses coffee grounds inside of a balloon. When pressed against an object the grounds flow around it. When a vacuum is applied to the balloon those grounds are locked in place, jamming themselves around the item for a firm grip. About a year ago we saw a hardware-store grade design which used a vacuum pump for suction and a shower head as the gripper body. This time around the plastic syringe serves as both.

The plastic tip was cut away and the resulting hole covered with a cloth to keep the coffee in place. After installing the coffee-filled balloon the grip can be operated by pulling the plunger to lock the grounds in place. It’s not going to be as easy to automate as a pump-based rig. But if you just want to toy with the concept this is the way to go.

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