A Low Cost, Dead Tree Touch Screen

Remember the “paperless office”? Neither do we, because despite the hype of end-to-end digital documents, it never really happened. The workplace is still a death-trap for trees, and with good reason: paper is cheap, literally growing on trees, and it’s the quickest and easiest medium for universal communication and collaboration. Trouble is, once you’re done scribbling your notes on a legal pad or designing the Next Big Thing on a napkin, what do you do with it?

If you’re anything like us, the answer to that question is misplacing or destroying the paper before getting a chance to procrastinate transcribing it into some useful digital form. Wouldn’t paper that automatically digitizes what you draw or write on it be so much better? That’s where this low-cost touch-sensitive paper (PDF link) is headed, and it looks like it has a lot of promise. Carnegie-Mellon researchers [Chris Harrison] and [Yang Zhang] have come up with cheap and easy methods of applying conductive elements to sheets of ordinary paper, and importantly, the methods can scale well to the paper mill to take advantage of economies of scale at the point of production. Based on silk-screened conductive paints, the digitizer uses electrical field tomography to locate touches and quantify their pressure through a connected microcontroller. The video below shows a prototype in action.

Current cost is 30 cents a sheet, and if it can be made even cheaper, the potential applications range from interactive educational worksheets to IoT newspapers. And maybe if it gets really cheap, you can make a touch-sensitive paper airplane when you’re done with it.

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The Internet of Non-Electronic Things

The bill of materials for even the simplest IoT project is likely to include some kind of microcontroller with some kind of wireless module. But could the BOM for a useful IoT thing someday list only a single item? Quite possibly, if these electronics-less 3D-printed IoT devices are any indication.

While you may think that the silicon-free devices described in a paper (PDF link) by University of Washington students [Vikram Iyer] and [Justin Chan] stand no chance of getting online, they’ve actually built an array of useful IoT things, including an Amazon Dash-like button. The key to their system is backscatter, which modulates incident RF waves to encode data for a receiver. Some of the backscatter systems we’ve featured include a soil sensor network using commercial FM broadcasts and hybrid printable sensors using LoRa as the carrier. But both of these require at least some electronics, and consequently some kind of power. [Chan] and [Iyer] used conductive filament to print antennas that can be mechanically switched by rotating gears. Data can be encoded by the speed of the alternating reflection and absorption of the incident WiFi signals, or cams can encode data for buttons and similar widgets.

It’s a surprisingly simple system, and although the devices shown might need some mechanical tune-ups, the proof of concept has a lot of potential. Flowmeters, level sensors, alarm systems — what kind of sensors would you print? Sound off below.

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Casein, Cello, Carrotinet, and Copper Oxide, Science Grab Bag

One of our favorite turnips, oops, citizen scientists [The Thought Emporium], has released his second Grab Bag video which can also be seen after the break. [The Thought Emporium] dips into a lot of different disciplines as most of us are prone to do. Maybe one of his passions will get your creative juices flowing and inspire your next project. Or maybe it will convince some clever folks to take better notes so they can share with the rest of the world.

Have you ever read a recipe and thought, “What if I did the complete opposite?” In chemistry lab books that’s frowned upon but it worked for the Reverse Crystal Garden. Casein proteins make cheese, glue, paint, and more so [The Thought Emporium] gave us a great resource for making our own and demonstrated a flexible conductive gel made from that resource. Since high school, [The Thought Emporium] has learned considerably more about acoustics and style as evidence by his updated cello. Maybe pulling old projects out of the closet and giving them the benefit of experience could revitalize some of our forgotten endeavors.

If any of these subjects whet your whistle, consider growing gorgeous metal crystals, mixing up some conductive paint or learning the magnetic cello. Remember to keep your lab journal tidy and share on Hackday.io.

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A Flexible Sensor That Moves With You

If you have a project in mind that requires some sort of gesture input or precise movements, it might become a nettlesome problem to tackle. Fear this obstacle no longer: a team from the Wyss Institute for Biologically Inspired Engineering at Harvard have designed a novel way to make wearable sensors that can stretch and contort with the body’s natural movements.

The way they work is ingenious. Layers of silicone are sandwiched between two lengths of silver-plated conductive fabric forming — by some approximation — a capacitance sensor. While the total surface area doesn’t change when the sensor is stretched — how capacitance sensors normally work — it does bring the two layers of fabric closer together, changing the capacitance of the band in a proportional and measurable way, with the silicone pulling the sensor back into its original shape as tension relaxes. Wires can be attached to each end of the band with adhesive and a square of thermal film, making an ideal sensor to detect the subtlest of muscle movements.

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Buttons, Sliders, and Touchpads All 3D Printed with PrintPut

[Jesse Burstyn] and some colleagues at Queen’s University and Carleton University (both in Canada) are delivering a paper at the INTERACT 2015 about PrintPut, their system for printing sensors directly into 3D printed objects. Using a printer with dual extrusion and conductive ABS filament, they have successfully formed capacitive touch sensors, digital resistive sensors, and analog resistive sensors.

In practice, this means they can print buttons, sliders, and even touch pads directly into objects. They also have a design for several pressure sensors and a flex sensor. The system includes scripts for the Rhinoceros 3D CAD package. Designers can create a model in any CAD package they want (including Rhinoceros) and then use these scripts to define the interactive areas.

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This One May Come as a Shock to Some

[Chris] seems to have commandeered a decent portion of the wife’s sewing room for his electronic adventures. As it is still her claim, she made it clear that his area needed some organization and a new desk. Dissatisfied with the look and feel of the replacement IKEA desk-like substance they acquired, he took it upon himself to ratchet up both the style and value by adding a copper laminate.

His decision is not purely based in aesthetic. If you’re following along, this means that his new electronics work surface is conductive. And yeah, it’s connected to ground at the wall. Although he doesn’t care for the stank of of anti-static mats or their susceptibility to fading and cracking, he does intend to use a tiny patch of it to keep his silicon happy.

[Chris] used a 20-gauge copper sheet that he cut and scored down to fit his Swedish sandwich wood base with enough margin for overhang. After scratching up one side of the copper sheet and one of the receiving base, he squidged down some adhesive nasty enough to require the rubber glove protocol and clamped it all together for several hours. Stay put the copper did, but stay flat it did not. After hammering down the overhang, [Chris] hand-burnished the copper in small swirls with a Scotch Brite pad to visually break up the slightly wavy surface. Instructional and hilarious play-by-play after the break.

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Wire loop game penalizes for touches by shrinking your wand

We really like this take on a conductive wire maze game. It’s the result of a 48-hour hackathon in Belgium which required that all projects stemming from the event use an Arduino. We think [Jan] and [Kristof] made perfect use of the prototyping device in the time allotted. The event organizers thought so too because this took top prize.

As you can see, the gaming area is two-sided, and consists of some copper wire bent into a maze. There’s a wand made out of a PVC pipe with a loop of braided cable running through it. The loop surrounds the copper track and each player needs to get from the beginning to the end, touching checkpoints along the way without coming in contact with the track.

Pretty standard, right? Well there’s a twist. At each checkpoint the Arduino signals a servo motor in the wand to make the loop smaller. Add to that a penalty/reward system: if you touch the track, your loop gets smaller and your opponent’s loop grows larger. Don’t miss the head-to-head action after the break.

This reminds us of that wire-based cave racer from a few years back. Continue reading “Wire loop game penalizes for touches by shrinking your wand”