6 panel diagram of process

Add Conductive Traces On Vacuum Formed Plastic With 3D Printing

Surface conductors on vacuum formed parts appear in many hacks, from cosplay armor to 3D touch pads and smart objects. But making them has always been painful. Either they had to be hand painted after forming, which looked sloppy and was labor intensive, or they had to be printed with some difficult to use stretchable ink tech. [Freddie Hong] and his group have another solution, using tech most hackers already have – a 3D printer and a vacuum former.

plastic tray with electrodes to sense foil wrapped chocolates
Smart tray created by this method.

They 3D print the traces with conductive PLA filament directly onto a base plastic sheet, and then vacuum form the whole thing. The filament is happy to deform when heated – it’s printer filament.

We like this process.  We’ve found conductive filament isn’t reliably resistive across vertical layers, but is reliable in the XY plane. Their method only requires one layer. Also, they suggest 3D printing a layer of non conductive PLA atop most of the conductor, like a PCB solder mask.

Conductive filament has a fair bulk resistance. They suggest electroplating it before applying the top mask layer. They also are exploring 3D printing logos, stripes, and such with colored filament, or even making surface detail like rivets on model parts or adding thickness where the plastic thins during vacuum forming.

Designing the 3D print requires guessing what bit of plastic sheet ends up where in the vacuum formed final part.  His group used a commercial program, t-sim,  to do the prediction and Grasshopper to import the result into Rhino3D. This seems a lot for a home hacker. Drawing lines on a test sheet and vacuum forming seems simpler.

We’ve looked at vacuum forming before. We did a piece on 3D printing bucks , and covered [Ted Brull]’s Kevo vacuum former back in 2015.

Thanks to [howielowe] for the tip.

A handheld printer printing "CHI 2022 and a capacitor symbol

Print-a-Sketch Turns Any Surface Into A Printed Circuit Board

Although powerful design software and cheap manufacturing services have made rolling your own PCBs easier than ever, there are some situations where a piece of FR-4 just doesn’t cut it: think art projects with hidden LEDs or biomedical applications that need to attach to the human body. For such occasions, [Narjes Pourjafarian] and her team at Saarland University in Germany developed Print-a-Sketch: a handheld device that lets you print electric circuits on almost any surface using conductive ink.  Also check out their academic paper (PDF).

The heart of the device is a piezoelectric print head, as used in some types of inkjet printer. It dispenses tiny droplets of silver nanoparticle ink, which is conductive enough to make useful electronic circuits by simply printing a schematic. Lines can be drawn to connect components, while customized footprints can hold LEDs, capacitors or even integrated circuits.

As demonstrated in the video embedded below, the Print-a-Sketch can be used in various different modes. In freehand mode, you can draw whatever you like just by moving the device around. But it also has several assisted sketching modes, where it can straighten out wobbly lines, draw multiple lines in parallel, or even print complete predefined shapes. Especially satisfying is the way it can draw resistors by literally printing zig-zagging lines.

Thanks to an optical motion sensor, similar to the ones used in gaming mice, the device knows at all times where it is and how fast it’s going. That enables the control circuitry to compensate for unsteady movement; the authors claim a printing precision of less than 0.5 mm. In addition, an RGB camera is used to detect the material underneath and adjust the amount of ink dispensed, depending on how absorbent the surface is: rough paper needs more ink to obtain a conductive trace than a ceramic tile.

The number of potential applications seems limitless: how about a yoga mat with integrated touch buttons to control the video player on your iPad? A piece of kinesiology tape with an integrated stretch sensor to measure the exact motion of your arm? Or a floor tile with a printed moisture sensor? All of these are demonstrated by the team, but we’re sure our readers can come up with many more ideas.

Of course, drawing circuits using conductive ink is not a new idea: previous projects either relied on drawing the entire thing by hand, or used traditional inkjet printers. But the Print-a-Sketch’s sophisticated hardware and software really put it in a league of its own. And since the entire design is open-source, you can simply build one and bring your ideas to life.

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Hands On With The Voltera V-One PCB Printer

Creating your own PC board is a rite of passage for many. These days, though, you can order super inexpensive boards and have them in very little time, so it doesn’t always make sense to build your own. Still, some people like the challenge, and others don’t want to wait even a few days. Probably everyone has dreamed of a 3D printer-like machine that would just crank out beautiful PCBs. The Voltera V-One isn’t quite at that level of sophistication, but it isn’t too far from it. [Great Scott] shows us how he built two different boards using the system in the video below. While the results were impressive, you can also see that there are several limitations, especially if you are not designing your board with the machine in mind.

One thing that is obvious is that the machine does need your help. In addition to aligning holes, you’ll need to install tiny rivets for vias and slightly less tiny rivets for through-hole components. The last time we looked at the machine, it didn’t do holes at all, but [Scott] shows the drill attachment which allows the machine to produce vias and support leaded components.

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Printed Circuits In The Palm Of Your Hand

If you’ve ever wanted to more fully integrate yourself with technology, you might have to thank a team of researchers — led by [Michael McAlpine] — at the University of Minnesota in the near future. They’ve developed a technique that allows circuits to be printed directly onto your skin, with the team arguing — once the low-cost printer is modified for compact portability — it would be ideal for ‘on-the-fly’ circuit needs.

“But the hand isn’t exactly a stable print bed,” you say. We hear you, and the team is actually one step ahead — the printer can compensate for subtle movements during the printing process by tracking markers placed on the hand. The ‘filament’ is made from silver flakes — akin to conductive ink — which prints and cures at room temperatures, and can be either peeled or washed off. We should hope so, as it’s meant to be layered on human skin.

Speaking of which, it can also print cells!

It’s only been tested on a mouse so far, but the same technology that allows the printer to accurately track the hand means that it could use bio-ink to directly add cells to a wound or some other epidermal affliction to help speed the healing process.

For the circuits, though, you’ll still need the other circuit components and a compact means to power them — to say nothing about the fact that if the circuit is water-soluble, then a little perspiration would cause the ink to run. We’re excited to see where this tech goes!

[Thanks for the tip, Qes!]

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Hybrid 3D-Printer Creates Complete Circuits, Case And All

The cool kids these days all seem to think we’re on the verge of an AI apocalypse, at least judging by all the virtual ink expended on various theories. But our putative AI overlords will have a hard time taking over the world without being able to build robotic legions to impose their will. That’s why this advance in 3D printing that can incorporate electronic circuits may be a little terrifying, at least to some.

The basic idea that [Florens Wasserfall] and colleagues at the University of Hamburg have come up with is a 3D-printer with a few special modifications. One is a separate extruder than squirts a conductive silver-polymer ink, the other is a simple vacuum tip on the printer extruder for pick and place operations. The bed of the printer also has a tray for storing SMD parts and cameras for the pick-and-place to locate parts and orient them before placing them into the uncured conductive ink traces.

The key to making the hardware work together though is a toolchain that allows circuits to be integrated into the print. It starts with a schematic in Eagle, which joins with the CAD model of the part to be printed in a modified version of Slic3r, the open-source slicing package. Locations for SMD components are defined, traces are routed, and the hybrid printer builds the whole assembly at once. The video below shows it in action, and we’ve got to say it’s pretty slick.

Sure, it’s all academic for now, with simple blinky light circuits and the like. But team this up with something like these PCB motors, and you’ve got the makings of a robotic nightmare. Or not.

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Play With A Papercraft Electronics Activity Book

As conductive ink becomes readily available and in greater varieties, we’re starting to see some intriguing applications. [Marion Pinaffo] and [Raphaël Pluviange] created a book of papercraft projects that employ silver-based ink for making a circuit’s wires, carbon-based ink for resistance, as well as color-changing ink. Electronics components’ leads are slipped into slits cut into the paper, connected to conductive-ink traces.

[Marion] and [Raphaël] use 555s, ATtiny85s, watch batteries, and other hardware to make each activity or project unique. A number of projects use a rolling ball bearing to make beeps in a piezo speaker. They also created beautifully designed pages to go with the electronics.

It looks like a fun way for neophytes to play around with electronics, and once the paper part is kaput, the user would be left with the hardware. Imagine one of those beginners googling to find the pinout of the Tiny85 or discovering the Stepped Tone Generator and makes one with the 555.

If you like this project you’ll appreciate the working papercraft organ and papercraft resistor calculator we previously published.

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Can You Build An E-ink Display From Scratch?

Modern displays are fascinating little things. In particular, the E-Ink displays employed in modern E-books achieve mesmerising paper like contrast with excellent standby power consumption.  Many of us at some point have had a go at experimenting with DIY displays, but been discouraged by the miniature scales involved. Driving them is hard enough, but building your own?

[MChel] has achieved some excellent success in building a simple E-Ink display. The account presented on this Russian electronics forum, graciously translated for us by Google Translate, outlines that the greatest barrier to pursing this in your home lab is creating the conductive layer that serve as electrodes for each pixel and depositing the thin layer of electrostatically charged ink pellets onto another transparent yet conductive film. [MChel] solution was to extract a small a portion of pre-deposited ink from a smashed and notoriously brittle E-ink display. Next, instead of attempting to build an ambitious and dense grid of electrodes, [MChel] etched a simple battery indicator on a PCB. The ink and the electrodes were then fused with some DIY graphite based conductive glue and sealed with some careful yet ingenuitive epoxy laying skills.

The DIY electrodes

The result is a working battery indicator that consumes no power, whilst reporting any remaining power.

There is something increasingly defiant and laudable about home-brewing technologies, otherwise thought to be confined to multi-million dollar factories. We have already covered how you should go about making some conductive glass and using it in your homemade LCD.