3D Printing, Raspberry Pi, and Fruit Flies: Low-Cost Custom Lab Equipment Helps in Study of Behavior

Thanks to 3D printing, it can cost far less money to produce necessary, customized laboratory equipment and tools than it used to. There are plenty of 3D printed microscopes, and we’ve also seen a 3D printed smartphone device that tests antibiotic drugs for antimicrobial susceptibility, as well as a small, DIY laboratory system. Now, researchers at the Imperial College London have used 3D printing to create a new mini robotic lab machine that’s used to test the behavior of fruit flies.

The researchers call the 3D printed device an ethoscope…not to be confused with a 3D printed stethoscope. It’s a self-contained machine that uses computerized video-tracking to record, or detect, the activities of fruit flies, and maybe someday other test animals like rats, in real time. The team combined a Raspberry Pi computer, equipped with a camera, with a few other simple components, like an SD card, infrared LED light, and a 3D printed structure called a behavioral arena, to build the ethoscope.

“The ethoscope is going to provide neuroscientists with a very new powerful tool to study, for instance, the biology of learning and memory or the function of sleep,” explained Dr. Giorgio Gilestro, head of the lab in the Department of Life Sciences at Imperial.

While many may think that fruit flies, or Drosophila melanogaster, are just those annoying little bugs that buzz around your kitchen, they are actually quite similar to humans in terms of genetics and behavior and are a very common research animal for neuroscience studies. They’re often used as models for studying multiple human conditions, such as stress, disease, and anxiety, and common human behaviors, like socializing and sleeping.

Most custom equipment can only be used to study a small amount of flies at once in these conditions, which is why the Imperial research team decided to develop the easy-to-use, inexpensive ethoscope.

The team recently published a study on the invention, titled “Ethoscopes: An open platform for high-throughput ethomics,” in PLoS Biology; co-authors include Quentin Geissmann, Luis Garcia Rodriguez, Esteban J. Beckwith, Alice S. French, Arian R. Jamasb, and Gilestro.

The abstract reads, “Here, we present the use of ethoscopes, which are machines for high-throughput analysis of behavior in Drosophila and other animals. Ethoscopes provide a software and hardware solution that is reproducible and easily scalable. They perform, in real-time, tracking and profiling of behavior by using a supervised machine learning algorithm, are able to deliver behaviorally triggered stimuli to flies in a feedback-loop mode, and are highly customizable and open source. Ethoscopes can be built easily by using 3D printing technology and rely on Raspberry Pi microcomputers and Arduino boards to provide affordable and flexible hardware.”

If you don’t have access to a 3D printer, an ethoscope can also be made using LEGOs or even folded cardboard, so long as it’s combined with a camera-equipped Raspberry Pi for quick and simultaneous recording and classification of the behavior of fruit flies. Onshape was used to design all of the parts, and the components were 3D printed using PLA filament on Ultimaker 2+ 3D printers.

Typically, researchers studying the activity of fruit flies watch recorded video of the flies and manually record the movements of each one – the great thing about the ethoscope is that it saves researchers time by doing this automatically. In addition, the device can be customized to manipulate the behavior of flies, so researchers can study how they respond. The Imperial team recently used its custom ethoscopes to study sleep deprivation – when the machine detected that a fly had been still for 20 seconds, it rotated the tube the fly was in so it would wake up. Other methods, including constantly shaking or tilting even if the flies are awake, are far less reliable.

“We can programme the machine to send stimuli to the flies only when they behave in a certain way, for example the robots can be programmed to give flies rewards only if they complete a learned task,” said Geissmann, a PhD student with the Department of Life Sciences at Imperial and the leader of the study. “It may appear surprising, but fruit flies are smart animals and they can do pretty much everything humans do: flies know how to look for food, shelter and mating partners; they learn to avoid predators and aggressive mates; they communicate, court and engage in social lives.”

The Imperial researchers have been developing the ethoscope for seven years, and often use the devices in their own research projects.

“The interdisciplinary environment found at Imperial was really instrumental for this type of work,” said Dr. Gilestro. “There are not many places in the world were biologists and engineers can influence each other’s work in such a powerful and productive manner.”

All of the software and hardware specifications for the ethoscope are available for free online.

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[Source/Images: Imperial College London]