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    A test model fitted with Littman hardware. Image: Glia Project

    This 3D-Printed Stethoscope Costs $5, Outperforms $200 Competitors

    Written by

    J.M. Porup

    Tarek Loubani, an emergency room doctor in Gaza, wants to apply the principles of open source software development to out-of-patent medical devices. His first success: A 3D-printed stethoscope head that costs 30 cents to make and, according to his tests, has better sound quality than the industry standard.

    Loubani is the head of the Glia project, whose team of hackers and surgeons designed and field-tested the stethoscope. Audio-frequency response curve tests showed the device not only exceeds international standards, but offers superior sound quality compared to the industry-leading Littmann Cardiology 3.

    The Littmann retails for $150-200. The Glia stethoscope, including the 3D printed head, tubing and ear piece, will cost around $5 to produce.

    Loubani founded the Glia project after the 2012 Israeli invasion of Gaza. "I had to hold my ear to the chests of victims because there were no good stethoscopes, and that was a tragedy, a travesty, and unacceptable," Loubani told attendees during a presentation at the Chaos Communications Camp in Zehdenick, Germany.

    The device was tested in a process the group dubbed the "Hello Kitty" protocol. During the test, which measures how much sound is transmitted at each frequency, the stethoscope is pressed against a balloon filled with water before sound is transmitted through the balloon. The abundance of cat-branded balloons available in Gaza at the time led to that nickname.

    The team's audio test setup. Image: Glia Project

    Loubani is so confident in the quality of the stethoscope that he expects the peer-review process to be a "cake walk."

    "This stethoscope is as good as any stethoscope out there in the world and we have the data to prove it," Loubani said.

    Loubani foresees a future in which lifesaving medical devices, like dialysis machines and electrocardiograms, can be 3D printed around the world for a fraction of their former cost. Inspired by the open source software movement, he keeps all his code on GitHub and encourages doctors and hardware hackers to contribute to the project in a collaborative way.

    "We made a list of these things, that if I could bring them into Gaza, into the third world in which I work and live, then I felt like I could change the lives of my patients," he explained. "I wanted the people I work with to take it, and to print it, and to improve it because I knew all I wanted to do was bring the idea."

    The Glia team is focused on developing the three most ubiquitous and expensive medical devices—the stethoscope, a pulse oximeter that monitors blood oxygen levels, and an electrocardiogram for cardiac patients. The latter two, Loubani explains, will use “PCBs [printed circuit boards] designed to be easy for people to make in low-resource settings with simple methods like toner transfer. The housing is 3D printed.”

    This test graph shows that the Glia model stethoscope produces higher volumes than the standard at a wide range of frequencies. Image: Glia Project

    By applying the open source, collaborative development process to these devices, Loubani hopes to revolutionize medical care in the developing world.

    The stethoscope design is complete, except for the y-piece, which Loudani is still tweaking. The y-piece splits the sound signal coming from the main tube connected to the stethoscope head into two signals going into the physician’s ears.

    The pulse oximeter design is finished, he said, but calibration, refinement of the firmware, and rigorous field testing remains before it will be ready for use in Gaza and elsewhere. The electrocardiogram PCB design is done, but the firmware and software design has not yet started, and Loudani estimated it will be two years before the device will be ready.

    Loubani was inspired to launch the project after testing his nephew's toy stethoscope, and was startled to find such good sound quality.

    Stethoscope prices remain high despite the expiration of fifty-year-old patents, and so he brought together a group of hardware hackers to work on the Glia model.

    "I can understand why these companies charge so much," he wrote. "[They] have no reason to undermine their profits. Why would 3M develop a stethoscope that's as good as their $200 model but a fraction of the cost? That's where doctors, hackers and tinkerers from all over the world take over to create these devices in a way that's affordable and accessible."

    Loubani said the 3D-printed version cost US$10,000 to develop, which he funded out of his own pocket.

    Loubani wrote that he sees himself following in the footsteps of the free software movement, and he aims to replace expensive proprietary medical solutions.

    "I started using GNU/Linux in 1994," he wrote, "because I appreciated the ethos of tinkering and openness...There was no doubt from the start that this would be a Free hardware project. The only question was how to make it work."