A Smart Bandage For Monitoring Chronic Wounds

Here at Hackaday, we’re always enthralled by cool biohacks and sensor development that enable us to better study and analyze the human body. We often find ourselves perusing Google Scholar and PubMed to find the coolest projects even if it means going back in time a year or two. It was one of those scholarly excursions that brought us to this nifty smart bandage for monitoring wound healing by the engineers of FlexiLab at Purdue University. The device uses an omniphobic (hydrophobic and oleophobic) paper-based substrate coupled with an onboard impedance analyzer (AD5933), an electrochemical sensor (the same type of sensor in glucometers) for measuring uric acid and pH (LMP91000), and a 2.4 GHz antenna for wirelessly transmitting the data (nRF24L01). All this is programmed with an Arduino Nano. They even released their source code.

To detect uric acid, they used the enzyme uricase, which is very specific to uric acid and exhibits low cross-reactivity with other compounds. They drop cast uric acid onto a silver/silver chloride electrode printed on the omniphobic paper. Similarly, to detect pH, they drop cast a pH-responsive polymer called polyaniline emeraldine salt (PANI-ES) between two separate silver/silver chloride electrodes. All that was left was to attach the electrodes to the LMP91000, do a bit of programming, and there they were with their own electrochemical sensor. The impedance analyzer was a bit simpler to develop, simply attaching un-modified electrodes to the AD5933 and placing the electrodes on the wound.

The authors noted that the device uses a much simpler manufacturing process compared to smart bandages published by other academics, being compatible with large-scale manufacturing techniques such as roll-to-roll printing. Overcoming manufacturing hurdles is a critical step in getting your idea into the hands of consumers. Though they have a long way to go, FlexiLab appears to be on the right track. We’ll check back in every so often to see what they’re up to.

Until then, take a look at some other electric bandage projects on Hackaday or even make your own electrochemical sensor.

The Ifs Make Learning To Code Child’s Play

Anyone who has done the slightest bit of programming knows about the “Hello, World!” program. It’s the archetypal program that one enters to get a feel for a new language or a new architecture; if you can get a machine to print “Hello, World!” back to you, the rest is just details. But what about teaching kids to program? How does one get toddlers thinking in logical, procedural ways? More particularly, what’s a “Hello, World!” program look like for the pre-literate set?

Those are the sort of questions that led to The Ifs by [Makeroni Labs]. The Ifs are educational toys for teaching kids as young as three the basics of coding. Each If is a colorful plastic cube with a cartoon face and a “personality” that reflects what the block does – some blocks have actuators, some have sensors. The blocks are programmed by placing magnetic tabs on the top representing conditions and actions. A kid might choose to program a block to detect when it’s being shaken, or when the lights come on, and then respond by playing a sound or vibrating. The blocks can communicate with each other too, so that when the condition for one block is satisfied, something happens on another block.

The Ifs look like a lot of fun, and they’re a great jumpstart on the logical thinking skills needed for coders and non-coders alike. We’re not alone in thinking this is a pretty keen project – the judges for this year’s Hackaday Prize selected The Ifs as one of the twenty finalists. Will it win? We’ll find out next week at the 2019 Hackaday Superconference. If you won’t be in Pasadena with us, make sure you tune in to the livestream to watch the announcement.

Controlling Quadcopters With Wireless Mouse Dongles

Last week we gave away a few Crazyflie 2.0 quadcopters to some cool Hackaday Prize entries. This quadcopter ships with the intention of being controlled by your smartphone. But it can also be controlled by a PC with USB dongle and an nRF24LU1+ SOC. [ajlitt] didn’t figure out he wanted the USB dongle (the Crazyradio) that can control this quad until after he used his gift code to claim his Crazyflie quad. No matter; the dongles for Logitech wireless keyboards and mice use the same radio as the Crazyflie and can be modded to make this quad fly.

The board inside the Logitech unifying receiver is a simple affair, with some pads for the USB connector, a crystal, the nRF24LU1+ radio module, and a few passives. To get this radio chip working with his computer, [ajlitt] simply needed to break out the SPI pins and wire everything to a Bus Pirate.

Getting the Crazyradio firmware onto this proved to be a little harder than soldering some magnet wire onto a few pins. The chip was first flashed without a bootloader, a full image with the bootloader was found, after wrangling a single byte into place, [ajlitt] had a working Crazyflie radio made from a wireless mouse dongle. The range isn’t great  – only 30 feet or so, or about as far as you would expect a wireless mouse to work. Excellent work, even if [ajlitt] is temporarily without a mouse.

The Crazyflie 2.0 is available from the Hackaday Store, along with the add-ons if you don’t want to hack your own.

Adding Kilometers To A Radio Meant Only For Meters

The NRF 24L01+ radio transceiver can be found in a lot of wireless project builds. But it’s only meant to work at a range of a few meters. [Achu Wilson] found that he could greatly extend the range by as much as 2 kilometers. All he needed to do was build this high-gain antenna.

He already had an idea of what he wanted to use the RF link for, so a directional antenna is no a problem. He chose a biquad setup with a back reflector, then used NEC2 to model the design and tweak it for the best performance possible. It only took him about two hours to complete the build, and manages a 10 dB gain. Not bad for some wire and a scrap of sheet meta.

This is the same transceiver chip used in the SNES wireless mod. If only we had a really powerful set of binoculars we could play the extremely long-distance game of Mario Kart we’ve always dreamed about.