It was one of the more interesting consumer tech stories floating around at the turn of the century, a disposable cell phone manufactured using a multi-layer folded paper circuit board with tracks printed in conductive ink. Its feature set was basic even by the standards of the day in that it had no display and its only function was to make calls, but with a target price of only $10 that didn’t matter. It was the brainchild of a prolific New Jersey based inventor, and it was intended to be the first in a series of paper electronic devices using the same technology including phones with built-in credit card payment ability and a basic laptop model.
The idea of a $10 mobile phone does not seem remarkable today, it’s possible that sum might now secure you something with features far in excess of the Nokias and similar that were the order of the day at that time. But when you consider that those Nokias could have prices well into three figures without a contract, and that the new features people considered exciting were things like integrated antennas or swappable coloured plastic covers rather than the multicore processors or high-res cameras we’re used to today, a phone so cheap as to be disposable promised to be very disruptive.
The product’s wonderfully dated website (Wayback Machine link, we’ve skipped the Flash intro for you) has pictures of the device, and the video below the break features shots of it in use as its inventor is interviewed. But by the end of 2002 the Wayback Machine was retrieving 404 errors from the server, and little more was heard of the product. No sign of one ever came our way; did any make it to market, and did you have one?
With the benefit of fifteen years hindsight, why did we not have paper mobile phones as part of the ephemera of the early years of the last decade? It was not a product without promise; a ten-dollar phone might have been a great success. And the description of a cheap laptop that talks to a remote server for its software sounds not unlike today’s Chromebooks.
Some of you might claim the product was vapourware, but given that they demonstrated a working prototype we’d hesitate to go that far. The likelihood is that it did not find the required combination of component price and manufacturing ease to exploit its intended market segment before its competition improved to the point that it could no longer compete. If you have ever taken apart a typical mobile phone of the period you’ll have some idea of why they were not cheap devices, for example the RF filter modules of the day were individually adjusted precision components. And paper-and-ink printed circuit boards are still a technology with a way to go even now, perhaps the idea was simply too far ahead of its time. Meanwhile within a relatively short period of time the price of simple candybar phones dropped to the point at which they would tempt the $10 buyer to spend more for a better product, so the window of opportunity had passed.
While hardcore body-hackers are starting to freak us out with embedded circuit boards under their skin, a new more realistic option is becoming available — temporary tech tattoos. They’re basically wearable circuit boards.
Produced by [Chaotic Moon], the team is excited to explore the future of skin-mounted components — connected with conductive ink in the form of a temporary tattoo. And if you’re still thinking why, consider this. If these tattoos can be used as temporary health sensors, packed with different biometric readings, the “tech tat” can be applied when it is needed, in order to monitor specific things.
In one of their test cases, they mount an ATiny85 connected to temperature sensors and an ambient light sensor on the skin. A simple device like this could be used to monitor someone’s vitals after surgery, or could even be used as a fitness tracker. Add a BLE chip, and you’ve got wireless data transfer to your phone or tablet for further data processing.
If you’ve ever made double-sided PCBs without professional equipment, you had to deal with connecting one side of the board to the other. You have a few obvious choices: 1) Rely on component leads to connect both sides (and solder both sides); 2) Create vias and solder wire to both sides of the board; or 3) Use through hole rivets. [Diyouware] had a different idea: use conductive ink. After a few false starts, they found a technique that seemed to work well.
This isn’t the first time we’ve heard of people trying conductive ink with varying degrees of success. The biggest problem, usually, is that the ink wants to run out of the hole. [Diyouware] has an interesting solution for this problem: Don’t drill the hole all the way thorough.
It’s amazing how affordable PCB fabrication has become. It has long been economical (although not always simple) to fabricate your own singe and double-sided boards at home, the access to professional fabrication is becoming universal. The drive continues downward for both cost and turnaround time. But there is growing interest in the non-traditional.
Over the last year we’ve seen a huge push for conductive-ink-based PCB techniques. These target small-run prototyping and utilize metals (usually silver) suspended in fluid (think glue) to draw traces rather than etching the traces out of a single thin layer of copper. Our question: do you think conductive in will become a viable prototyping option?
Voltera V-One Circuit Board Prototyping Machine
I recorded this interview at 2015 CES but was asked not to publish it until their crowd funding campaign went live. If you haven’t been paying attention, Voltera is at almost 400% of their $70k goal with 26 days remaining. This printer definitely works. You can print circuits, solder components or reflow them, and there’s even a second non-conductive ink that can be used to insulate between traces when they cross over one another. In the video [Alroy] suggests Voltera for small production runs of 10-20 boards. Would you see yourself using this for 10-20 boards?
Personally, I think I could solder point-to-point prototypes in less time. Consider this: the V-One will print your traces but you still must solder on the components yourself. If the board design reaches a high level of complexity, that timing may change, but how does the increased resistance of the ink compared to copper traces affect the viability of a board? I assume that something too complex to solder point-to-point would be delving into high-frequency communications (think parallel bus for LCD displays, etc.). Is my assumption correct? Do you think conductive ink will get to the point that this is both viable and desirable over etching your own prototypes and how long before we get there?
Now, I certainly do see some perfect use-cases for Voltera. For instance, introduction to circuit design classes. If you had one of these printers at the middle school or high school level it would jump-start interest in electronics engineering. Without the need for keeping chemical baths like Cuperic Chloride or Ferric Chloride on hand, you could walk students through simple board design and population, with the final product to take home with them. That’s a vision I can definitely get behind and one that I think will unlock the next generation of hardware hackers.
Correction: [Arachnidster] pointed out in the comments that Voltera is still working on being able to reflow boards printed by the V-One. On their Kickstarter page they mention: “(Reflow onto Voltera printed boards is currently under development)”
The plotter in question is a 1983 HP HIPLOT DMP-29 that was, like all old HP gear, a masterpiece of science and engineering. These electronics were discarded (preserved may be a better word) and replaced with modern hardware. The old servo motors ran at about 1.5A each, and a standard H-Bridge chip and beefy lab power supply these motors were the only part of the original plotter that were reused. For accurate positioning, a few 10-turn pots were duct taped to the motor shafts and fed into the ATMega1284p used for controlling the whole thing.
The final iteration of hardware wasn’t exactly what [Connor] and [Feiran] had in mind, but that’s mostly an issue with the terrible conductivity of the conductive ink. They’ve tried to fix this by running the pen over each line five times, but that introduces some backlash. This is the final project for an electrical engineering class, so we’re going to say that’s alright.
There are two printers being shown off at the 2015 Consumer Electronics shows which really spark our interest. They are the Voltera and the Voxel8. Each is taking on the challenge of printing circuits. They use similar techniques but approach the problem in very different ways.
[Michael Bell] poses with the Voxel8
Quad on the print bed of the Voxel8
3D printed quadcopter — conductive traces and all
The Voxel8 marries the idea of a 3D printer with a silver conductive ink dispenser. You start by modeling your entire design, hardware and electronics, all in one. The printer will then begin the 3D print, pausing when necessary for you to add electronics and mechanicals. With the parts — and their pins — in place it lays out the conductive ink to connect the components and then continues with the 3D printing to finish the object.
[Alroy Almeida] poses with the Voltera
PCB demo, colored traces are for insulation between layers
PCB with components populated
The Voltera is a PCB printer that uses silver conductive ink. It prints the ink onto a substrate. Pads made of the ink are used to solder the components in place after the printing is finished. The trick added to this design is the ability to print two layers, both on the same side of the board. There is a second ink material which is an insulator. It is laid over the first conductive layer before the second is printed, allowing traces to cross over each other.
Congratulations to the Voltera team who won $50k from the 2015 Hardware Battlefield at CES.
We didn’t see enough to shake our skepticism about the viability of silver conductive ink to take the place of copper on prototype boards. But if anyone is going to make the case that it is plausible these two offerings will.
One interesting thing about the Voxel8 is the ability to specify point-to-point wiring as a “part”. If you do so, the machine will pause while you solder the wires in place before it encapsulates them with the rest of the print. Of course if you’re going to do this manually it shouldn’t really matter which printer you use for it.
What do think about the future of conductive ink for prototyping? Lets us know in the comments.
[Frank Zhao] wanted to try his hand at making a transparent circuit board. His plan was to etch the paths with a laser cutter and fill in the troughs with conductive ink. The grooves are ~0.1mm deep x ~0.8mm wide.
He used nickel ink, which is slightly cheaper than silver ink. The ink was among the least of his problems, though. At a measured resistance of several hundred ohms per inch, it was already a deal breaker since his circuit can’t function with a voltage drop above 0.3V. To make matters worse, the valleys are rough due to the motion of the laser cutter and don’t play well with the push-to-dispense nature of the pen’s tip. This caused some overflow that he couldn’t deal with elegantly since the ink also happens to melt acrylic.
[Frank] is going to have another go at it with copper foil and wider tracks. Do you think he would have fared better with silver ink and a different delivery method, like a transfer pipette? How about deeper grooves?
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