According to the US Department of Health and Human Services, 22 patients die each day in need of an organ transplant because the demand for organs far outpaces the supply. If the compelling idea of producing 3D printed organs is realized many lives could be saved.
A big challenge in this field is to produce printable material that can support cells and is also permeable to nutrients. A hydrogel is a type of synthetic cross-linked polymer that is highly water absorbent. Hydrogels are commonly used as tissue engineering scaffolds for cells because of their biocompatibility.
This is a hot topic in the field right now, and many people around the world are working on developing new bioprinting methods. A challenge to the development of these methods is how well the printed object corresponds to the plan.
A group of Chinese scientists did a study of how various printing parameters affected printing fidelity. They published their results last week in Scientific Reports, the premier scientific journal Nature brand’s open source online journal.
The printing material or bioink must be liquid before printing and gel after printing. To make their hydrogels, they used sodium alginate (the same material this group used to print vasculature), gelatin, and a solution of calcium chloride as a cross linker.
In order to develop a bioprinting process, they feel it is important to understand the impact of changing the printing parameters including air pressure, temperature, feed rate, and printing distance. Another parameter included the ratio of gelatin and alginate.
Using a lab-built 3D printer, they started out with printing 1D lines on a flat surface, connected at different angles. They moved on to lattice shapes as shown in the image above, looking at how well the lattice maintained its shape with different line spacings. The hydrogel tends to spread somewhat upon printing. The printing surface was cooled so that the gel formed. The experiments also determined the impact of gravity.
They used extrusion based printing as opposed to other types of printing because cells are sensitive to thermal and mechanical stress. They found that the 3D printing process did not damage or kill mouse fibroblast cells suspended in the hydrogel as it only had a slight impact on cell survival.
Finally, the looked at a 3D object with successive printed layers as shown in the figure below.
a- Digital model b- Outline of the first layer c- First layer with outline filled in d- Views of 3D structure with about 30 printed layers
The removal and reconstruction of a large part of the chest wall is often required to treat malignant tumors that occur in the cartilage or bone of the ribcage. However, the potential for complications in these types of surgeries is unacceptably high—the overall complication rate is over 40% and the 30-day mortality rate is up to 17%. Many of the complications are respiratory-related.
A team of doctors at Asturias University Central Hospital, in Asturias, Spain suspected that the patients’ difficulty breathing resulted from the stiffness of the implants. They performed a surgery using 3D printed titanium rib implant designed to be more flexible.
Using 3D printing to produce rib implants to replace parts of the ribcage is not new. A world-first surgery with a 3D printed implant was also performed about a year ago, also in Spain, according to articles published in Forbes and Gizmodo (entry image credit).
Because each person’s ribcage structure is unique, using 3D printing to produce such implants has the obvious advantage of producing an exact replica.
Both implants were made using information from a CT scan, and printed using the same technique—layer-by-layer electron beam melting starting with titanium powder in a high vacuum by an Arcam Q10 printer.
In this more recent surgery, the doctors made the implant less rigid by incorporating articulations as shown in the figure, on the right side of the implant. As you can see such a complicated object could only be created in one piece using 3D printing techniques. They published their findings in the Journal of Thoracic Disease.
Picture of titanium rib implant, Journal of Thoracic Disease
The 57 year old male patient regained normal function after six weeks without complications.
CT scan eight weeks after surgery, Journal of Thoracic Disease
Two years ago, the White House declared a week in mid-June the “national week of making,” to coincide with the DC Maker Faire. Since then, they have continued this tradition, providing funding and initiatives to encourage hands-on STEM education. This year’s national week of making starts on Friday, June 17-23 and DC’s Maker Faire is June 19th and 20th.
At last year’s events, President Obama said, “Makers and builders and doers— of all ages and backgrounds—have pushed our country forward, developing creative solutions to important challenges and proving that ordinary Americans are capable of achieving the extraordinary when they have access to the resources they need,” quoted on the White house blog announcing last year’s makers’ week.
In this spirit, the Department of Education launched a contest three months ago to challenge high school students to design makerspaces for their schools. They could receive support for the process, such as a six-week boot camp class to learn design skills. The top winning designs will get the funding to get their space built at their schools. Winning entries will be announced soon.
The NIH library is holding a series of events relating to healthcare to celebrate the week, including a special symposium on June 20: “Making Health: Inspiring Innovative Solutions for Research and Clinical Care” and another event at Georgetown University on June 23 that will showcase various organizations involved at the intersection of making and healthcare.
Susannah Fox, Chief Technology Officer at the U.S. Department of Health and Human Services (HHS), will give a keynote speech on how the democratization of technology can improve health. She also posted an article on Medium last week, about the department’s work in this area.
The article featured the image above, of the first makerspace designed specifically for healthcare at the Galveston University of Texas Medical Branch hospital. It’s located on a patient floor, to help nurses and patients develop and build customized objects to improve their care.
The NIH library will hold a series of classes and demos the rest of the week, including:
How to print from the NIH library’s newest 3D printer
Converting medical images from CT and MRI scans into 3D printable models using 3D-Slicer and ZBrush from Pixelogic
Creating protein models using Chimera and how to prepare them for printing using Meshmixer
An introduction to SOLIDWORKS
Classes on how to use open source software such as Blender and OpenSCAD
Schools and communities are encouraged to host their own events, using the hashtags weekofmaking and nationofmakers to promote them.
What are you doing to celebrate the national week of making?
Casey Steffen has a background in video game animation and a Master’s degree in biological visualization but he describes himself as a “medical illustrator and a type I diabetic” in the video introduction to his RocketHub crowdfunding page, that raised money to support a project to make educational models of the protein hemoglobin, that has 4,659 atoms. The proposal was completely funded two years ago.
The project addresses confusion surrounding the common hemoglobin A1c (HbA1c) test. Unlike the blood sugar measurement, it represents the average over three months (the lifetime of a red blood cell) of the fraction of bloodstream HbA1c (hemoglobin with sugar molecules attached as shown in the the models). If this number is above a certain range (7% for people with diabetes, according to WebMD) it means blood sugar has not been well controlled. A higher number is indicative of prolonged elevated blood sugar. It’s used for long term tracking of how patients manage their blood sugar.
The hemoglobin models provide patients with a physical and visual representation of what the test means, so they can better understand what’s going on in their body, and why it’s important to control their blood sugar. An elevated blood sugar causes damage to certain tissues, like the eyes and blood vessels in the feet, slowly, over a long period of time.
To get the hemoglobin models right, Steffen collaborated with Patricia Weber, a structural biologist and Mary Vouyiouklis, his endocrinologist. When Steffen met Michael Gulen, who was a prototype development director at a company that makes action figures, a collaboration was born. Wired Magazine covered their story about five years ago.
Steffen’s company, Biologic Models, makes models of proteins for scientific and medical education. The physical models of proteins are created from x-ray crystallography data sets. For some of the models, like the hemoglobin ones, 3D printing from a Form 1 3D printer serves to make the prototype for plaster molds, to finally cast the models in silicone.
The company partners with the 3D printing company Shapeways to print several proteins including the Zika virus shell and the Ebola virus ectodomain (the part that fuses to the cell membrane).
Digital preview of Zika virus shell
Ebola virus ectodomain
Customers can also choose to have the company provide a plan for 3D printing their favorite protein by providing its PDB ID from the protein data bank, a resource of protein structure x-ray crystallography data. Customers can then have it 3D printed or print it themselves.
Based on a post from formlabs.
A company in Brazil called Artis Tecnologia has developed medical 3D printing technologies to aid in skull resection surgery. They demonstrated their techniques on a volunteer patient who received surgery for free at the university hospital of the Federal University of São Paulo (UNIFESP). They published an article about it two weeks ago in the International Journal of Computer Assisted Radiology and Surgery.
Their technologies allow the removal of a skull tumor and the implantation of a prosthesis in a single surgery. The company works with the doctors to plan the surgery and make the mold for the prosthesis. In this case the company donated the mold and the surgical navigator for the computer assisted surgery (CAS).
Planning of the prosthesis
Surgical planning First, the doctors take a CT scan of the patient, following a specific protocol so that it is precise enough to make the personalized mold. The scans are imported into the company’s EximiusMed software and which is compatible with the surgical navigator. The company is responsible for deciding on the surgery margin, and providing an image of the prosthesis, which is approved by the surgeon. The planning and production of the mold takes four days.
Mold production The personalized mold is made with Magics software from Materialise, a company from Belgium. They make the mold for the prosthesis as well as a model of the bone fault, with submillimeter precision, using a 3D printer from 3D Systems, which uses layer-by-layer manufacturing in layers 0.16 inches thick. It is made from a plaster-like material, and finished with an insulator on the inside and scratch proof finish on the outside. Then, the mold and bone fault are packed in blister packaging, sealed with Tyvek, and sterilized by ethylene oxide, before shipping.
Images of the mold
Making the prosthesis The prosthesis, made from PMMA during surgery, is created using a hand press as shown in the video.
The PMMA in plastic phase undergoes a slight contraction, and using 20% extra PMMA and a press, ensures the correct size for the prosthesis. The extra material drains out of the mold and can be easily removed from the prosthesis. The mold also absorbs heat from the exothermic reaction. It is pressed until polymerization is complete which takes ten to twenty minutes. Finally the prosthesis is washed generously with saline solution.
Placing the prosthesis on the skull fault
The surgeon decides how to perforate and attach the prosthesis, in this case with titanium clips The clips are used to stabilize the prosthesis but not hold it in place. The prosthesis should overlap the edges of the skull fault as shown in the figure so it does not slip into the cranial cavity.
Images after surgery
SME is holding an inaugural conference in about a week and a half, titled “Building Evidence for 3D Printing Applications in Medicine.” It’s sponsored by Materialize, a company that develops software for 3D printing and produces 3D-printed projects for researchers, clinicians, and consumers.
This is a crucial topic for doctors, patients, and the medical 3D printing industry. 3D printing will not be widely accepted in the clinic without compelling, systematic evidence that it is better than existing technologies and improves outcomes for patients. This type of evidence is also needed to gain reimbursement approval from insurance companies.
According to a blog post on the Materialize website for hospitals, the goal of the conference is to “work on a common set of guidelines regarding methodologies and assessment methods” for gathering clinical evidence of outcomes of the use of 3D printing in medicine.
Because each device manufactured by 3D printing is different, and the planning stage has a great impact on the outcome, the problem of developing standardized guidelines for collecting clinical evidence is challenging. As we’ve seen here at Embodi3D.com, the promise of 3D printing to help a great number of patients makes this problem worth pursuing.
One of the speakers in the following video, Andy Christensen, a business strategist for medical devices, 3D printing, and medical imaging, gets into the specifics of what types of evidence will be needed, “In medicine, the evidence 3D printing technologies should focus on gathering, will include things like overall patient outcomes, the invasiveness of the procedure, the total cost of the procedure, and things like revision rates for surgeries or other procedures. Now, while some of these are fairly easy, some of these may be fairly difficult to gather, and I think that’s a good reason a collaborative effort to gather information will be best.” Developing a collaborative effort to gather information is the goal of the conference.
Over two days, the conference will feature the clinical, engineering, and economic perspectives on the major thrusts of medical 3D printing: 3D printed anatomical models, 3D printed instruments and surgical guides, and 3D printed patient-specific implants. There will be many opportunities for discussion. Representatives from government agencies, the FDA and NIH, will join industry and clinical professionals to share their thoughts.
This initiative is part of the SME Medical Manufacturing Innovations Program (MMI) and the group will organize ongoing discussions online.
The conference will be co-located with RAPID, the annual SME 3D-printing conference, so that people can conveniently attend both. RAPID will of course also have many sessions on 3D printing for medical applications.
There’s still time to register to attend the RAPID conference held at the Orange County Convention Center in Orlando, Florida, on May 16-19. The “Building Evidence for 3D Printing Applications in Medicine” conference was only open to supporters and people significantly involved in 3D printing with relevant perspectives, through an application process. Embodi3D.com will continue to follow the outcomes of this highly relevant conference.
Tissue engineering can't expand into three dimensions as long as cells can't access oxygen and nutrients via blood vessels. This remains a big challenge for the printable organ and tissue engineering communities.
Monica Moya and Elizabeth Wheeler, biomedical engineers at Laurence Livermore National Laboratory, are working on a way to solve this “plumbing problem,” as Moya puts it, using 3D bioprinting.
Moya has previously developed microfluidic devices to test the effect of mechanical cues on vessel growth, and published her work in the journal Lab on a Chip. Now she and Wheeler are collaborating on moving to a 3D printing platform. Lawrence Livermore National Laboratory published a blog post last month describing their recent work.
First, they had to make sure that the printing techniques were compatible with cell viability. They had to change out the extrusion and fluidic parts of a standard 3D-printer, to eliminate the high temperatures and shear forces that would kill the cells.
The bioink, a fluid with biological components, contains endothelial cells, fibrin, and fibroblast cells. The viscosity had to be finely controlled, so that it would remain liquid inside the printer, and gel once in contact with the bed, to print out the tissue support for the vessels.
To make tubular vessels, a mixture of alginate (a polysaccharide isolated from seaweed) and fibroblast cells, is printed from a coaxial needle (a needle within a needle) resulting in printed vessel structures, called biotubes. Finally, more tissue bio-ink is laid down, enveloping the biotubes. The biotubes are hardened by flowing calcium solution through the tubes. The tissue patch starts to grow its own vessels, but it looks like spaghetti, with no organization. The alginate and calcium tubes eventually dissolve, leaving the vessels formed by the cells. Future planned developments include directing the vessel formation with nutrient and mechanical cues.
The youtube video demonstrates the printing process:
The photo above shows Monica Moya holding a dish with several of these biotubes. She explained their reasoning, “If you take this approach of co-engineering with nature you allow biology to help create the finer resolution of the printed tissue. We’re leveraging the body’s ability for self-directed growth, and you end up with something that is more true to physiology. We can put the cells in an environment where they know, ‘I need to build blood vessels.’ With this technology we guide and orchestrate the biology.”
Moya and Wheeler did an AMA on Reddit back in December to discuss their work with interested members of the public.
They have made tissue patches the size of one square centimeter, the size of a fingernail. Future directions include larger tissue patches. Potential applications of this work include drug testing, toxicology studies, and implantable tissues.
Moya and Wheeler’s work is part of a larger project called iCHIP (in vitro Chip-based Human Investigational Platform) looking to create a “human on a chip” where different teams are working on making tissue models of the stomach, liver, heart, kidney, brain, blood–brain barrier, immune system, and lungs, also described in a blog post on the Lawrence Livermore National Laboratory website.
Photo credit: Lanie L. Rivera Lawrence Livermore National Laboratory
Brain tumors located at the base of the skull are some of the most challenging to treat, because of their proximity to the brain stem, as well as important nerves and blood vessels in the head and neck (Johns Hopkins). The brain stem maintains breathing and heartbeat, the basics of life. Tumors found here are known as “skull base tumors” based on their location, not the type of tumor.
A group of doctors at Toho University Omori Medical Center in Tokyo, Japan, hope to improve surgical models for skull base tumors.
3D printed models are often made from opaque materials such as plaster, which make it difficult to visualize the essential brain structures. The doctors’ idea was to develop a surgical model where the tumor was made from a mesh structure.
First they had to design the mesh. They made a series of objects with different spacing between the mesh and different mesh thickness. They made 20 trials of each structure, a total of 400 models. Once they decided which mesh provided the most transparency and structural integrity (they chose the one in the photo below), they proceeded to test the tumor models.
Image Credit: Acta Neurochirurgica
To make the all the models, the researchers used the Z Printer 450 from 3D systems which uses binder jetting, where layers of a plaster powder are fused with a binding agent to make the model. The models were then coated in paraffin wax to make them more durable.
Once they decided on which grid to use for the tumor models, models were made from brain scans taken of four patients between 2007 and 2014. The imaging used for each patient was CT angiography (CTA) for the skull, MRI for the tumor and brainstem, and 3D digital subtraction angiography (DSA) for the blood vessels.
Twelve neurosurgeons (the authors of the study) evaluated models based on the visibility of the various brain structures comparing a solid tumor, a mesh tumor, and no tumor. (see photo above)
They determined that they the mesh tumor structure enabled them to both visualize the deep brain structures, and also understand the spatial relationships between those structures and the tumor.
The method was limited by the physical vulnerability of the mesh and the difficulty of judging the surface of the mesh tumor compared to the solid tumor model. The authors expected improvements in 3D printing technology to enable thinner mesh as well as translucent material.
Kosuke Kono et al. published a paper describing their study online two weeks ago in Acta Neurochirurgica: The European Journal of Neurosurgery.
Heart disease is the leading cause of death in the USA and other developed countries. Imagine the number of lives that could be saved if doctors could predict heart attacks before they happen.
Most heart attacks are caused by a buildup of cholesterol and triglycerides (called plaques) inside heart arteries that rupture, form blood clots, and block the artery.
But not all plaques rupture and not all plaque ruptures cause disease. An Australian team of medical doctors and mechanical engineers hopes to predict where plaques will form, which plaque sites will rupture, and which ruptured sites will cause heart attacks. With this knowledge cardiologists could place a stent to hold open the afflicted artery before the attack occurs.
As a river twists and branches, sediment builds up on some banks, and the water sweeps others bare. The same is true of arteries and plaque formation. And each individual has different arterial branches.
Knowing an individual’s heart artery structure will enable the design of individualized 3D-printed models to help plan surgery, and design perfectly fitted stents, which would aid in the current challenges of stent placement. Peter Barlis, the leader of the team, holds up a 3D printed artery in the leading image above.
Another member of the team, associate professor Andre McIsaac, said, “the long term outcome is dependent on how well our stents are put in, in fact how well they’re deployed and expanded and having the right size stent in the right spot in the correct coronary artery.”
Dr. Peter Barlis at the University of Melbourne and a team of researchers are working on predicting the sites of future heart attacks, by using state-of-the-art imaging techniques and computer models.
Images captured from inside a heart artery using Optical Coherence Tomography. Photo credit: University of Melbourne
The imaging technique, called optical coherence tomography (OCT), is a type of CT scan, except instead of x-rays it uses near-infra red light, at the edge of the visual spectrum. In the video below, you can see a red light on the camera. The light does not penetrate as deeply as x-rays do, so a wire-like camera is inserted into the heart via a vein. It can be performed at the same time as a routine angiogram. Barlis brought OCT imaging to Australia in 2009, and now it’s used in all major hospitals there. It was approved by the FDA for use in cardiology in the US in 2010.
But researchers can’t know if they actually prevented an attack or if it would not have happened in the first place.
They are attempting to connect arterial branch location, the types of mechanical stress on arterial walls, blood flow, and existing plaque to the risk of rupture. Barlis and a team of researchers published a review article in the European Heart Journal in February of this year about current computer modelling techniques to give other cardiologists insights into this growing field.
Press release at EurekAlert!
Cassidy, a tuxedo kitten with a white mustache and socks, lost his hind limbs from below the knee at birth. When he was found starving after nine weeks, his wounds infected with E. coli, the emergency vet recommended euthanasia. But Shelly Roche refused to give up on him. She runs the TinyKittens rescue operated out of Fort Langley, B.C., Canada, that specializes in lost causes. She nursed him back to health, with the Internet cheering him on.
This video shows Cassidy walking with a leash and harness to hold up his rear end, then getting a little wheelchair and finally running around and bounding off his rear leg stumps.
Cassidy as a young kitten trying his 3D printed wheelchair. Photo credit: CatChannel.com
Two local high school students made him a wheelchair using their school’s 3D printer. This was not the last time 3D printing would help Cassidy. Handicapped Pets Canada also provided one that he used up until recently. Now that Cassidy has outgrown his wheelchairs, he gets around riding Roche’s Roomba.
But the Roomba is only a temporary solution. Cassidy is being fitted for prosthetic leg extensions. Last week, in the first step toward receiving prosthetics, Cassidy got Botox injections to relax the muscles of his rear legs, for ongoing physical therapy.
Roche said of Cassidy’s prosthetics, "I'm not sure if they use titanium or carbon fiber. I'm not sure what the end-point will be. I tell people he's going to get fancy new bionic legs."
That will be up to Dr. Denis Marcellin-Little and the team at North Carolina State University working on Cassidy’s prosthetics. Marcellin-Little is an expert in custom prosthetics and physical therapy. Like a real-life Dr. House for dogs and cats, Dr. Marcellin-Little gets the most challenging cases, where existing methods cannot provide treatment, so he and an international team of collaborators develop new ones.
The process for building a custom implant starts with a CT scan. Then, 3D-printed models of bones may be made. Marcellin-Little has over a decade-long collaboration with Dr. Ola Harrysson of the department of Industrial Systems and Engineering building implants. Marcellin-Little and Harrysson have invented a technique called osseointegration, where a titanium implant gets attached directly to bone via a honeycombed surface the bone grows to fill. The implant itself is made using a type of metal 3D printing called electron beam melting (EBM) where titanium powder is melted in successive layers to make the object.
Several news articles have mentioned the cost of Cassidy’s care. $10,000 has been spent on Cassidy already. The implant procedures can cost up to $20,000 per leg.
The procedure does not only benefit a single animal. Marcellin-Little talks of translating the technique to human patients “All the progress we make in free-form fabrication very quickly gets translated to human prosthetic research. Free-form transdermal osseointegration will cross over at some point to human patients.”
The rugged, replaceable, customizable, lightweight, and low cost nature of 3D printing technology make it ideal to make prosthetics for children, who quickly outgrow and/or wear them out.
E-nable is an online community of volunteers, parents, makers, and medical professionals committed to providing 3D printed prosthetics to children who need them.
Dr. Gloria Gogola, a pediatric hand surgeon at Shriners Hospitals for Children-Houston collaborated with E-nable and volunteer bioengineering students and faculty from Rice University to help children and parents build their own prosthetics. She published a paper along with two other researchers last week summarizing their work in The Journal of Hand Surgery to explain the advantages of using 3D printing for children’s prosthetics to other surgeons.
At almost a hundredth of the cost of traditional prosthetics, for $50 as opposed to $4,000, they are comparable to the price of a pair of shoes.
A recent Upworthy story told the “origin story” of E-nable. Blogger cdmalcolm gave an overview of E-nable’s charity work in a post for Embodi3D about a year ago.
Since then, membership in the E-nable Google+ group has doubled, reaching over 8,000 members as of this publication. They have brought hands to 40 countries around the world, providing them for free to children in need.
The recent story of four-year-old Anthony from Chile posted on enablingthefuture.org’s blog illustrates the process each child follows to get a new hand.
Because Anthony does not have a wrist, the joint powering most of E-nable’s devices, he needed an elbow actuated device. Anthony’s mother took his measurements and decided with the volunteers’ help that the Team Unlimbited Arm was the best fit.
Parents and children can also choose to help design, customize, print, and build the hands themselves. According to Jon Schull, the founder of E-nable, they take about three hours to print, and two hours to build, for $5 worth of raw material. Two big repositories for free designs are available from the National Institutes of Health and Enablingthefuture.org.
Volunteers helped print the arm and gave it to Anthony for a trial period to test the fit. They realized a he needed a thermoplastic cast for a comfortable, snug fit on his small arm.
Volunteer Francisco Nilo and Anthony sharing an obligatory fistbump. Photo credit: ProHand3D and Enablingthefuture.org
Coordinating was challenging as Anthony lived in Valparaiso, on the Pacific coast, a two hour drive northwest of Santiago, where the volunteers and 3D printing company, ProHand3D, were located.
Finally, local Santiago tattoo artist and illustrator Cesar Castillo painted the device with Spider Man designs, Anthony’s favorite superhero.
Final Spider-Man arm. Photo credit: ProHand3D and Enablingthefuture.org
To continue with more fun themes, in January of this year E-nable began having design contests every month. This month’s theme is Steampunk and the winner will receive copperfill and bronzefill filament coils, social media fame, and have their device displayed at the Maker Faire in Nantes, France. Past themes included Star Wars and task-specific devices.
Each hand is as unique as its child owner. Chile volunteer Francisco Nilo said of Anthony, “His mom shared with us that since Anthony received his Spiderman arm, he uses it all the time, even for sleeping! We know no one uses these devices all day long, but perhaps the superhero design has influenced him just a bit!”
People interested in volunteering for E-nable or those interested in procuring a prosthetic hand for a child may visit http://enablingthefuture.org/ and contact email@example.com
Researchers from the Department of Biology at the University of Oregon, Eugene, have come up with an innovative use of 3D printing to study the biology of flower mimicry.
One of their models was the “Dracula Orchid” (Dracula effleurii). Despite its vampiric name, the flower is not carnivorous. They attract flies as pollinators, not food. Dracula here means “little dragon,” referring to their appearance.
Bitty Roy, the principle investigator on the study, described the pollination process: "What the orchid wants the fly to do when it arrives is to crawl into the column, whereupon the orchid sticks a pollinium (mass of pollen) onto the fly so that the fly can't possibly get it off. The fly then goes to another orchid, which then pulls it off."
The researchers travelled to Ecuador, South America, to study the orchids and their fly pollinators in the wild.
Roy also put the study into a larger evolutionary and ecological context: "Mimicry is one of the best examples of natural selection that we have," she said. "How mimicry evolves is a big question in evolutionary biology. In this case, there are about 150 species of these orchids. How are they pollinated? What sorts of connections are there? It's a case where these orchids plug into an entire endangered system. This work was done in the last unlogged watershed in western Ecuador, where cloud forests are disappearing at an alarming rate."
Roy and her research team wanted to know whether the different visual parts of the flower, its scent, or a combination of both, were responsible for attracting the flies. They presented their results in a paper published last month in The New Phytologist.
"Dracula orchids look and smell like mushrooms. We wanted to understand what it is about the flowers that is attractive to these mushroom-visiting flies," said Tobias Policha, the lead author of the paper.
The researchers designed their study to separate out the different parts of the flower: the triangular outer part (the calyx) and the inner pouch-shaped part (the labellum).
From upper left, counter-clockwise: completely artificial flower, completely real flower; real calyx, artificial labellum; artificial calyx, real labellum. Photo credit: Aleah Davis
To manufacture the artificial flowers, the team collaborated with Melinda Barnadas, co-owner of Magpie Studios, an arts studio expert in creating scientific art and models for museums.
The process to make the artificial flowers had several steps: casting the real flowers in impression molds, making a positive plaster cast of the molds, digitally scanning the cast, then 3D printing the files using a Zcorp Spectrum 510 printer. Finally the 3D-printed molds served to cast the flowers from medical grade, scentless silicon. The color was done using dye encapsulated in silicon, so the flies couldn’t smell it.
Real flower, on left, and a series of artificial flowers, created from 3D printed molds, in decreasing order of fly attractiveness. Image from research paper.
As a result of this study the researchers found that the flies were most attracted to the scented labellum. They hope their idea will be used in other studies where genetically modifiable models are not available.
Quotes from researchers pulled from the press release at EurekaAlert!