Electrochemistry At Home

A few years ago, I needed a teeny, tiny potentiostat for my biosensor research. I found a ton of cool example projects on Hackaday and on HardwareX, but they didn’t quite fulfill exactly what I needed. As any of you would do in this type of situation, I decided to build my own device.

Now, we’ve talked about potentiostats before. These are the same devices used in commercial glucometers, so they are widely applicable to a number of biosensing applications. In my internet perusing, I stumbled upon a cool chip from Texas Instruments called the LMP91000 that initially appeared to do all the hard work for me. Unfortunately, there were a few features of the LMP91000 that were a bit limiting and didn’t quite give me the range of flexibility I required for my research. You see, electrochemistry works by biasing a set of electrodes at a given potential and subsequently driving a chemical reaction. The electron transfer is measured by the sensing electrode and converted to a voltage using a transimpedance amplifier (TIA). Commercial potentiostats can have voltage bias generators with microVolt resolution, but I only needed about ~1 mV or so. The problem was, the LMP91000 has a resolution of ~66 mV on a 3.3 V supply, mandating that I augment the LMP991000 with an external digital-to-analog converter (DAC) as others had done.

However, changing the internal reference of the LMP91000 with the DAC confounded the voltage measurements from the TIA, since the TIA is also referenced to the same internal zero as the voltage bias generator. This seemed like a problem other DIY solutions I came across should have mentioned, but I didn’t quite find any other papers describing this problem. After punching myself a little, I thought that maybe it was a bit more obvious to everyone else except me. It can be like that sometimes. Oh well, it was a somewhat easy fix that ended up making my little potentiostat even more capable than I had originally imagined.

I could have made a complete custom potentiostat circuit like a few other examples I stumbled upon, but the integrated aspect of the LMP91000 was a bit too much to pass up. My design needed to be as small as possible since I would eventually like to integrate the device into a wearable. I was using a SAMD21 microcontroller with a built-in DAC, therefore remedying the problem was a bit more convenient than I originally thought since I didn’t need an additional chip in my design.

I am definitely pretty happy with the results. My potentiostat, called KickStat, is about the size of a US quarter dollar with a ton of empty space that could be easily trimmed on my next board revision. I imagine this could be used as a subsystem in any number of larger designs like a glucometer, cellphone, or maybe even a smartwatch.

Check out all the open-source files on my research lab’s GitHub page. I hope my experience will be of assistance to the hacker community. Definitely a fun build and I hope you all get as much kick out of it as I did.

Wearable Device For Preventing SUDEP (Sudden Unexpected Death In Epilepsy)

Epilepsy is a neurological disorder characterized by the occurrence of seizures. Epilepsy can often prevent patients from living a normal life since it’s nearly impossible to predict when a seizure will occur. The unpredictability of the seizures makes performing tasks such as driving extremely dangerous. One of the challenges in treating epilepsy is the condition is still not very well understood.

Neurava, a recent startup company from Purdue University, aims to change this fact. Neurava is developing a neck wearable that “records key biological signals related to epilepsy.” None of the press releases we’ve found so far elaborate on what those biological signals are. Though we have some guesses of our own, we’ll leave it to the Hackaday community to speculate for the time being. One of the major hurdles in using biological signals to treat conditions like epilepsy both lies in the accuracy of the measurement itself in addition to how well the measurement correlates to the underlying condition. From the looks of it, Neurava has been working on this technology for a long time and are certainly more aware of these challenges than we are.

Neurava’s wearable includes a few other functionalities we’ve come to expect in this era of smart devices such as wireless data transmission to both the physician and patient, physician dashboard to monitor the patient’s progress over extended periods of time, and in-time alerts in the event a seizure is detected.

Neurava appears to have garnered a bit of publicity in these last few months and are currently securing seed money to help advance their technology. We’ll check in every so often to see how they’re doing.

Purdue Meta-AR-App Allows Instructors And Students To Build Their Own AR Learning Content

Augmented reality (AR) in the classroom has garnered a bit of interest over the years, but given the increased need for remote and virtual learning these days, it might be worth taking a closer look at what AR can offer. Purdue University’s C Design Lab thinks they’ve found a solution in their Meta-AR platform. The program allows an instructor to monitor each student’s work in real-time without being in the same classroom as the student. Not only that, but the platform allows students to collaborate in real-time with each other giving each other tips and feedback while also being able to interact with each other’s work, no matter where they may be physically located.

What we find really cool is the real-time feedback the software provides to the students. The system can sense what the students are touching and can help students in their given task, providing real-time feedback on what they are doing, how things should fit together, and what type of outcomes the students can expect given their trajectory. It also appears the system isn’t limited to AR markers but provides a very expansive toolbox for instructors and students to build on. C Design Lab is doing quite a bit of user feedback studies, continually incorporating input from students to further the platform. That’s definitely critical to ensuring the system is user-friendly.

We can easily see how something like this might scale to an industrial setting for training people how to use complex machinery, to a medical school to help prepare students to do surgery or to help develop molecular diagnostics tools. Check out the other learning tools C Design Lab is developing.

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 Auto-Bartender

It’s the end of the academic semester for many students around the globe, so here comes the flurry of DIY projects. Always a great time to check out all the cool hacks from our readers all over the world. One project that piques our interest comes courtesy of [Jason Ummel] and his Auto-Bartender. (Video, embedded below.)

[Jason] developed this project as a part of his robotics class taught by Professor Martinez, one of our friends at FlexiLab. Powered by one of our favorite microcontrollers, the ATmega328, the Auto-Bartender is driven by a single 12 V motor coupled with 10 individual valves for separate drinks. Drinks are pumped into a cup sitting on top of a scale, allowing the device to know how much of each drink has been dispensed. The entire setup is controlled using a smartphone application developed in MIT App Inventor, a super-easy way to prototype Android applications.

Furthermore, [Jason] incorporated a number of user-centered design considerations into his project. These include an LCD to display updates, a green LED to indicate the device is in progress, and a buzzer to let the user know the drink is complete.

We really like the combination of craftsmanship, electronics hardware design, and software development that [Jason] put into his project. It’s the kind of project we know our readers will enjoy.

It looks like Jason substituted tap water for Whiskey and Dr. Pepper for his demo. Not exactly what we had in mind, but I guess he still has exams to finish.

Cool project [Jason]! We can’t wait to see Auto-Bartender on Hackaday.io.

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Purdue University’s IEEE branch participated in this year’s Marine Advanced Technology Education Center Competition, taking second place for the Hybris ROV seen above. The competition included several compulsory functions, including the ability to cap an underwater oil well, collect biological samples, and take water samples at depth.

What they came up with is a quick and agile watercraft that easily overcomes a lot of the hardware hangups that typically plague ROV builds. There are eight thrusters, four for vertical motion and the other four take care of horizontal movement. The gripper mechanism can be clearly seen on the front of the craft, with two cylindrical containers housing the electrical components.

Don’t miss out on the project definition page. Each challenge is discusses in detail, along with the team’s solution. We were impressed by the amount of information they have posted, including overview of each electrical component as well as design files and source code. If you want to see how the first run of the competition went, click through the break to find embedded video.

Continue reading “Purdue IEEE ROV”