Growing Algae For Fun And Profit

Supposedly, writes [Severin], algae is a super food, can be used as biofuel, and even be made into yoga mats. So he’s built an algal reactor at Munich Maker Lab, to try to achieve a decent algal yield.

You might expect that  sourcing live algae would be as simple as scraping up a bit of green slime from a nearby pond, but that yields an uncertain mix of species. [Severin] wanted Chlorella algae for his experiment because its high fat content makes it suitable for biodiesel experiments, so had to source his culture from an aquatic shop.

The reactor takes the form of a spiral of transparent plastic tube surrounding a CFL lamp as a light source, all mounted on a lasercut wooden enclosure housing a pump. A separate glass jar forms a reservoir for the algal-rich water. He does not mention whether or not he adds any nutrient to the mix.

Left to its own devices the machine seems to work rather well, a 48 hour session yielding an impressively green algal soup. Sustained running does cause a problem though, the pipes block up with accumulated algae and the machine needs cleaning by blasting it with high pressure water and a healthy dose of nuts and bolts.

This isn’t the first algal reactor we’ve featured here on Hackaday, we had this Arduino-powered one back in 2009. But mostly the algae that have appeared here have been of the bioluminescent variety, as with this teaching project, or this night light.

DIY Electrical Body Fat Analyzer

Whether you are trying to drop some fat or build some muscle, it’s important to track progress. It’s easy enough to track your weight, but weight doesn’t tell the whole story. You might be burning fat but also building muscle, which can make it appear as though you aren’t losing weight at all. A more useful number is body fat percentage. Students from Cornell have developed their own version of an electrical body fat analyzer to help track body fat percentage.

Fat free body mass contains mostly water, whereas fat contains very little water. This means that if you were to pass an electrical current through a body, the overall bioelectrical impedance will vary depending on how much fat or water there is. This isn’t a perfect system, but it can give a rough approximation in a relatively easy way.

The students’ system places an electrode on one hand and another on the opposite foot. This provides the longest electrical path possible in the human body to allow for the most accurate measurement possible. An ATMega1284P is used to generate a 50kHz square wave signal. This signal is opto-isolated for user safety. Another stage of the circuit then uses this source signal to generate a 10ua current source at 50kHz. This is passed through a human body and fed back to the microcontroller for analysis.

The voltage reading is sent to a MATLAB script via serial. The user must also enter in their weight and age. The MATLAB script uses these numbers combined with the voltage reading to estimate the body fat percentage. In order to calibrate the system, the students measured the body fat of 12 of their peers using body fat calipers. They admit that their sample size is too small. All of the sample subjects are about 21 years old and have a similar body fat percentage. This means that their system is currently very accurate for people in this range, but likely less accurate for anyone else. Continue reading “DIY Electrical Body Fat Analyzer”

THP Hacker Bio: AKA

Thermal imaging cameras are the new hotness when it comes building DIY tools that are much less expensive than their commercial counterparts. [Mike Harrison] built a very high-resolution version from Flir’s Lepton module, but an IR temperature sensor and a servo can also create a decent image. [AKA] played around with some of these thermal imaging modules, but found them a little hard to interface. Panasonic’s Grid-EYE module, however is reasonably cheap as far as thermal imaging devices go, and can be read over an I2C bus.

[AKA]’s entry for the Hackaday Prize, the GRID-EYE Thermal Camera is one of two Prize entries that survived the great culling and made it into the quarterfinalist round. [AKA] was kind enough to sit down and do a short little interview/bio with us, available below.

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THP Hacker Bio: Kenji Larsen

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I met up with [Kenji Larsen] at HOPE X last weekend, and I’m fairly certain he was the coolest person at a conference full of really cool people. Talking to him for a little bit, you get a sense of what it would be like to speak with [Buckmister Fuller], [Tesla], or any of the other ‘underappreciated, but not by people in the know’ minds scattered about history. I’ll just let his answers to our hacker bio questions demonstrate that.

7033431402348237268[Kenji]’s project for The Hackaday Prize is the Reactron Overdrive. It’s not just one board he’s building here, but an entire suite of sensors, interfaces, and nodes that form a complete human to machines – note the plural ‘machines’ – interface. When you consider that no one knows what the Internet of Things actually is, and that [Kenji] is working on IoT 3.0, you get a sense that there’s really something here. Also, his project log has a Tron Recognizer in it. That has to count for something, right?

Interview/Bio below.

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THP Hacker Bio: hackersbench

 

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Remote sensing applications that make sense and cents? (sorry, couldn’t help ourselves) That’s what [hackersbench], aka [John Schuch], aka [@JohnS_AZ] is working on as his entry for The Hackaday Prize.

He received a multi-thousand-dollar water bill after having an underground pipe break and leak without knowing it. His idea will help you notice problems like this sooner. But if you actually have a way to capture data about your own water use you also have a tool to help encourage less wasteful water use habits. We wanted to learn more about the hacker who is working on this project. [John’s] answers to our slate of questions are after the break.

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THP Hacker Bio: nsted

 

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Have you ever wanted to build a robot arm, or even a full robot, but were put off by the daunting task of making all of those articulations work? Moti could make that a lot easier. The project seeks to produce smart servo motors which can connect and communicate in many different ways. It’s a great idea, so we wanted to know more about the hacker behind the project. After the jump you’ll find [nsted’s] answers to our slate of question for this week’s Hacker Bio.

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THP Hacker Bio: David Cook

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[David Cook] has been on the front page with gnarly hacks many times. We’re happy to present his Hackaday Projects profile as this week’s Hacker Bio.

His entry for The Hackaday Prize is something of a one-wireless-pair-to-rule-them approach to connected devices which he calls LoFi. We were delighted by his first demo video which is exactly what we envisioned for preliminary entries; [David] explains the concept and how he plans to implement it using a few visual aids to drive the point home.

Join us after the break to find out more about [David]. Oh, if you’re wondering about the times he’s been featured on Hackaday, check out his capacitor/coin cell swap which is one of our favorites.

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