Now, you can hold a copy of your brain in the palm of your hand


New 3D printing technique enables faster, better, and cheaper models of patient-specific medical data for research and diagnosis

Summary:
Medical imaging technologies like MRI and CT scans produce high-resolution images as a series of ‘slices,’ making them an obvious complement to 3D printers, which also print in slices. However, the process of manually ‘thresholding’ medical scans to define objects to be printed is prohibitively expensive and time-consuming. A new method converts medical data into dithered bitmaps, allowing custom 3D-printed models of patient data to be printed in a fraction of the time.

This 3D-printed model of Steven Keating’s skull and brain clearly shows his brain tumor and other fine details thanks to the new data processing method pioneered by the study’s authors.
Credit: Wyss Institute at Harvard University

What if you could hold a physical model of your own brain in your hands, accurate down to its every unique fold? That’s just a normal part of life for Steven Keating, Ph.D., who had a baseball-sized tumor removed from his brain at age 26 while he was a graduate student in the MIT Media Lab’s Mediated Matter group. Curious to see what his brain actually looked like before the tumor was removed, and with the goal of better understanding his diagnosis and treatment options, Keating collected his medical data and began 3D printing his MRI and CT scans, but was frustrated that existing methods were prohibitively time-intensive, cumbersome, and failed to accurately reveal important features of interest. Keating reached out to some of his group’s collaborators, including members of the Wyss Institute at Harvard University, who were exploring a new method for 3D printing biological samples.

“It never occurred to us to use this approach for human anatomy until Steve came to us and said, ‘Guys, here’s my data, what can we do?” says Ahmed Hosny, who was a Research Fellow with at the Wyss Institute at the time and is now a machine learning engineer at the Dana-Farber Cancer Institute. The result of that impromptu collaboration — which grew to involve James Weaver, Ph.D., Senior Research Scientist at the Wyss Institute; Neri Oxman, Ph.D., Director of the MIT Media Lab’s Mediated Matter group and Associate Professor of Media Arts and Sciences; and a team of researchers and physicians at several other academic and medical centers in the US and Germany — is a new technique that allows images from MRI, CT, and other medical scans to be easily and quickly converted into physical models with unprecedented detail. The research is reported in 3D Printing and Additive Manufacturing.

“I nearly jumped out of my chair when I saw what this technology is able to do,” says Beth Ripley, M.D. Ph.D., an Assistant Professor of Radiology at the University of Washington and clinical radiologist at the Seattle VA, and co-author of the paper. “It creates exquisitely detailed 3D-printed medical models with a fraction of the manual labor currently required, making 3D printing more accessible to the medical field as a tool for research and diagnosis.”

Imaging technologies like MRI and CT scans produce high-resolution images as a series of “slices” that reveal the details of structures inside the human body, making them an invaluable resource for evaluating and diagnosing medical conditions. Most 3D printers build physical models in a layer-by-layer process, so feeding them layers of medical images to create a solid structure is an obvious synergy between the two technologies.

However, there is a problem: MRI and CT scans produce images with so much detail that the object(s) of interest need to be isolated from surrounding tissue and converted into surface meshes in order to be printed. This is achieved via either a very time-intensive process called “segmentation” where a radiologist manually traces the desired object on every single image slice (sometimes hundreds of images for a single sample), or an automatic “thresholding” process in which a computer program quickly converts areas that contain grayscale pixels into either solid black or solid white pixels, based on a shade of gray that is chosen to be the threshold between black and white. However, medical imaging data sets often contain objects that are irregularly shaped and lack clear, well-defined borders; as a result, auto-thresholding (or even manual segmentation) often over- or under-exaggerates the size of a feature of interest and washes out critical detail.

The new method described by the paper’s authors gives medical professionals the best of both worlds, offering a fast and highly accurate method for converting complex images into a format that can be easily 3D printed. The key lies in printing with dithered bitmaps, a digital file format in which each pixel of a grayscale image is converted into a series of black and white pixels, and the density of the black pixels is what defines the different shades of gray rather than the pixels themselves varying in color.

Similar to the way images in black-and-white newsprint use varying sizes of black ink dots to convey shading, the more black pixels that are present in a given area, the darker it appears. By simplifying all pixels from various shades of gray into a mixture of black or white pixels, dithered bitmaps allow a 3D printer to print complex medical images using two different materials that preserve all the subtle variations of the original data with much greater accuracy and speed.

The team of researchers used bitmap-based 3D printing to create models of Keating’s brain and tumor that faithfully preserved all of the gradations of detail present in the raw MRI data down to a resolution that is on par with what the human eye can distinguish from about 9-10 inches away. Using this same approach, they were also able to print a variable stiffness model of a human heart valve using different materials for the valve tissue versus the mineral plaques that had formed within the valve, resulting in a model that exhibited mechanical property gradients and provided new insights into the actual effects of the plaques on valve function.

“Our approach not only allows for high levels of detail to be preserved and printed into medical models, but it also saves a tremendous amount of time and money,” says Weaver, who is the corresponding author of the paper. “Manually segmenting a CT scan of a healthy human foot, with all its internal bone structure, bone marrow, tendons, muscles, soft tissue, and skin, for example, can take more than 30 hours, even by a trained professional — we were able to do it in less than an hour.”

The researchers hope that their method will help make 3D printing a more viable tool for routine exams and diagnoses, patient education, and understanding the human body. “Right now, it’s just too expensive for hospitals to employ a team of specialists to go in and hand-segment image data sets for 3D printing, except in extremely high-risk or high-profile cases. We’re hoping to change that,” says Hosny.

In order for that to happen, some entrenched elements of the medical field need to change as well. Most patients’ data are compressed to save space on hospital servers, so it’s often difficult to get the raw MRI or CT scan files needed for high-resolution 3D printing. Additionally, the team’s research was facilitated through a joint collaboration with leading 3D printer manufacturer Stratasys, which allowed access to their 3D printer’s intrinsic bitmap printing capabilities. New software packages also still need to be developed to better leverage these capabilities and make them more accessible to medical professionals.

Despite these hurdles, the researchers are confident that their achievements present a significant value to the medical community. “I imagine that sometime within the next 5 years, the day could come when any patient that goes into a doctor’s office for a routine or non-routine CT or MRI scan will be able to get a 3D-printed model of their patient-specific data within a few days,” says Weaver.

Keating, who has become a passionate advocate of efforts to enable patients to access their own medical data, still 3D prints his MRI scans to see how his skull is healing post-surgery and check on his brain to make sure his tumor isn’t coming back. “The ability to understand what’s happening inside of you, to actually hold it in your hands and see the effects of treatment, is incredibly empowering,” he says.

“Curiosity is one of the biggest drivers of innovation and change for the greater good, especially when it involves exploring questions across disciplines and institutions. The Wyss Institute is proud to be a space where this kind of cross-field innovation can flourish,” says Wyss Institute Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School (HMS) and the Vascular Biology Program at Boston Children’s Hospital, as well as Professor of Bioengineering at Harvard’s John A. Paulson School of Engineering and Applied Sciences (SEAS).

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Pediatric Medication Safety in the Emergency Department


Abstract

Pediatric patients cared for in emergency departments (EDs) are at high risk of medication errors for a variety of reasons. A multidisciplinary panel was convened by the Emergency Medical Services for Children program and the American Academy of Pediatrics Committee on Pediatric Emergency Medicine to initiate a discussion on medication safety in the ED. Top opportunities identified to improve medication safety include using kilogram-only weight-based dosing, optimizing computerized physician order entry by using clinical decision support, developing a standard formulary for pediatric patients while limiting variability of medication concentrations, using pharmacist support within EDs, enhancing training of medical professionals, systematizing the dispensing and administration of medications within the ED, and addressing challenges for home medication administration before discharge.

 

  • Abbreviations:
    AAP
    American Academy of Pediatrics
    ACEP
    American College of Emergency Physicians
    ADE
    adverse drug event
    CDS
    clinical decision support
    CPOE
    computerized physician order entry
    ED
    emergency department
    ENA
    Emergency Nurses Association

 

Background

Despite a national focus on patient safety since the publication of the Institute of Medicine (now the National Academy of Medicine) report “To Err is Human” in 1999, medical errors remain a leading cause of morbidity and mortality across the United States.1 Medication errors are by far the most common type of medical error occurring in hospitalized patients,2 and the medication error rate in pediatric patients has been found to be as much as 3 times the rate in adult patients.3,4 Because many medication errors and adverse drug events (ADEs) are preventable,1 strategies to improve medication safety are an essential component of an overall approach to providing quality care to children.

The pediatric emergency care setting is recognized as a high-risk environment for medication errors because of a number of factors, including medically complex patients with multiple medications who are unknown to emergency department (ED) staff, a lack of standard pediatric drug dosing and formulations,5 weight-based dosing,6,7 verbal orders, a hectic environment with frequent interruptions,8 a lack of clinical pharmacists on the ED care team,9,10 inpatient boarding status,11 the use of information technology systems that lack pediatric safety features,12 and numerous transitions in care. In addition, the vast majority of pediatric patients seeking care in EDs are not seen in pediatric hospitals but rather in community hospitals, which may treat a low number of pediatric patients.13 Studies also outline the problem of medication errors in children in the prehospital setting. A study of 8 Michigan emergency medical services agencies revealed errors for commonly used medications, with up to one-third of medications being dosed incorrectly.14 Medication error rates reported from single institutions with dedicated pediatric EDs range from 10% to 31%,15,16 and in a study from a pediatric tertiary care center network, Shaw et al6 showed that medication errors accounted for almost 20% of all incident reports, with 13% of the medication errors causing patient harm. The authors of another study examined medication errors in children at 4 rural EDs in northern California and found an error rate of 39%, with 16% of these errors having the potential to cause harm.17 The following discussion adds to the broad topic of medication safety by introducing specific opportunities unique to pediatric patients within EDs to facilitate local intervention on the basis of institutional experience and resources.

Strategies for Improvement

A multidisciplinary expert panel was convened by the Emergency Medical Services for Children program and the American Academy of Pediatrics (AAP), through its Committee on Pediatric Emergency Medicine, to discuss challenges related to pediatric medication safety in the emergency setting. The panel included emergency care providers, nurses, pharmacists, electronic health record industry representatives, patient safety organization leaders, hospital accreditation organizations, and parents of children who suffered ADEs. The panel outlined numerous opportunities for improvement, including raising awareness of risks for emergency care providers, trainees, children, and their families; developing policies and processes that support improved pediatric medication safety; and implementing best practices to reduce pediatric ADEs. Specific strategies discussed by the panel, as well as recent advances in improving pediatric medication safety, are described.

Decreasing Pediatric Medication Prescribing Errors in the ED

Computerized Physician Order Entry

Historically, the majority of pediatric medication errors were associated with the ordering phase of the medication process. Specific risks related to pediatric weight-based dosing include not using the appropriate weight,6 performing medication calculations based on pounds instead of the recognized standard of kilograms,6 and making inappropriate calculations, including tenfold dosing errors.1820 Childhood obesity introduces further opportunity for dosing error. In addition to the lack of science to guide medication dosing in patients with obesity,21 frequent underdosing22 is reported, and currently available resuscitation tools are commonly imprecise.23 Furthermore, there are limited opportunities for prescription monitoring or double-checking in the ED setting, and many times calculations are performed in the clinical area without input from a pharmacist.9 The implementation of computerized physician order entry (CPOE) and clinical decision support (CDS) with electronic prescribing have reduced many of these errors, because most CPOE systems obviate the need for simple dose calculation. However, CPOE systems have not fully eliminated medication errors. Commercial or independently developed CPOE systems may fail to address critical unique pediatric dosing requirements.12,24 Kilogram-only scales are recommended for obtaining weights, yet conversion to pounds either by the operator or electronic health record may introduce opportunity for error into the system. In addition, providers may override CDS, despite its proven success in reducing errors.16,25 Prescribers frequently choose to ignore or override CDS prescribing alerts, with reported override rates as high as 96%.26 Allowing for free text justification to override alerts for nonformulary drugs may introduce errors. The development of an override algorithm can help reduce user variability.27 As the use of CPOE increases, one can expect that millions of medication errors will be prevented.28 For EDs that do not use CPOE, preprinted medication order forms have been shown to significantly reduce medication errors in a variety of settings and serve as a low-cost substitute for CPOE.2932

Standardized Formulary

The Institute of Medicine (now the National Academy of Medicine) recommends development of medication dosage guidelines, formulations, labeling, and administration techniques for the pediatric emergency care setting.5 Unfortunately, there are currently no universally accepted, pediatric-specific standards with regard to dose suggestion and limits, and dosing guidelines and alerts found in CPOE are commonly provided by third-party vendors that supply platforms to both children’s and general hospitals. The development of a standard pediatric formulary, independent of an adult-focused system, can reduce opportunities for error by specifying limited concentrations and standard dosage of high-risk and frequently used medications, such as resuscitation medications, vasoactive infusions, narcotics, and antibiotics, as well as look-alike and sound-alike medications.33 A standard formulary will allow for consistent education during initial training and continuing medical education for emergency care providers, creating a consistent measure of provider competency. At least 1 large hospital organization has successfully implemented this type of change.34 In addition, the American Society of Health-System Pharmacists is working with the Food and Drug Administration to develop and implement national standardized concentrations for both intravenous and oral liquid medications.35

ED Pharmacists

Currently, many medications are prepared and dispensed in the ED without pharmacist verification or preparation because many EDs lack consistent on-site pharmacist coverage.9,36 In a survey of pharmacists, 68% reported at least 8 hours of ED coverage on weekdays, but fewer than half of EDs see this support on weekends, with a drastic reduction in coverage during overnight and morning hours.37 The American College of Emergency Physicians (ACEP) supports the integration of pharmacists within the ED team, specifically recognizing the pediatric population as a high-risk group that may benefit from pharmacist presence.38 The Emergency Nurses Association (ENA) supports the role of the emergency nurse as well as pharmacy staff to efficiently complete the best possible medication history and reduce medication discrepencies.39,40 The American Society of Health-System Pharmacists suggests that ED pharmacists may help verify and prepare high-risk medications, be available to prepare and double-check dosing of medications during resuscitation, and provide valuable input in medication reconciliation, especially of medically complex children whose medications and dosing may be unknown to ED staff and who present without a medication list or portable emergency information form.41 Medically complex patients typify the difficulty with medication reconciliation, with an error rate of 21% in a tertiary care facility.42 In this study, no 1 source from the parent, pharmacy, and primary provider group was both available and appropriately sensitive or specific in completing medication reconciliation. Pharmacist-managed reconciliation has had a positive impact for admitted pediatric patients and may translate to the emergency setting.43,44 ED pharmacists can also help monitor for ADEs, provide drug information, and provide information regarding medication ingestions to both providers and patients and/or families.45

Dedicated pharmacists can be integrated through various methods, such as hiring dedicated pharmacy staff for the ED,7 having these staff immediately available when consulted, or having remote telepharmacy review of medication orders by a central pharmacist.46,47 Although further research is needed on the potential outcomes on medication safety and return on investment when a pharmacist is placed in the ED, current experience reveals improvements in medication safety when a pharmacist is present.48 Studies from general EDs reveal significant cost savings as well,49 with the authors of 1 study in a single urban adult ED identifying more than $1 million dollars of cost avoidance in only 4 months.50

Training in Pediatric Medication Safety

Dedicated training in pediatric medication safety is highly variable in the curricula of professional training programs in medical, nursing, and pharmacy schools.51 Although national guidelines support the training of prehospital personnel with specific pediatric content and safety and error-reduction training,52 a nearly 35% prehospital medication error rate for critical medications for pediatric patients remains.14 At the graduate medical education level, the curricula of pediatric and emergency medicine residency programs and pediatric emergency medicine fellowship programs do not define specific requirements for pediatric medication safety training.5355 The same is true for pharmacy programs.56 Although schools of pharmacy include pediatric topics in their core curricula, pediatric safety advocates believe there is an opportunity for enhanced and improved training.57

Experts in pediatric emergency care from the multidisciplinary panel recommend development of a curriculum on pediatric medication safety that could be offered to all caregivers of children in emergency settings. A standard curriculum may include content such as common medication errors in children, systems-improvement tools to avoid or abate errors, and the effects of developmental differences in pediatric patients. Demonstrating competency on the basis of this curriculum is 1 means by which institutions may reduce risks of medication errors.

Decreasing Pediatric Medication Administration Errors in the ED

The dispensing and administration phases serve as final opportunities to optimize medication safety. Strategies to reduce errors include standardizing the concentrations available for a given drug, having readily available and up-to-date medication reference materials, using premixed intravenous preparations when possible, having automated dispensing cabinets with appropriate pediatric dosage formulations, using barcoded medication administration,58 having pharmacists and ED care providers work effectively as a team, and having policies to guide medication use.59,60 Although yet to be studied in the ED environment, smart infusion pumps have shown promise in other arenas in reducing administration errors for infusions.61

Nurses are held accountable by each state’s nurse practice act for the appropriateness of all medications given. Nursing schools teach the 5 rights of medication administration: the right patient, the right medication, the right dose, the right time, and the right route.62 Elliott and Liu63 expand the 5 rights to include right documentation, right action, right form, and right response to further improve medication safety. Simulated medication administration addresses opportunities beyond those captured within these rights and may have implications within the ED.64 Additionally, given the association of medication preparation interruptions and administration errors,65 the use of a distraction-free medication safety zone has been shown to enhance medication safety.66,67 Implementation of an independent 2-provider check process for high-alert medications, as suggested by The Joint Commission, also reduces administration errors.68 Both the Institute for Safe Medication Practices and The Joint Commission provide excellent guidance on these topics.69

Decreasing Pediatric Medication Errors in the Home

Recognizing and addressing language barriers and health literacy variability in the ED can affect medication safety in the home. Nonstandardized delivery devices continue to be used in the home, and dosing error rates of greater than 40% are reported.70 Advanced counseling and instrument provision in the ED are proven to decrease dosing errors at home.71 Pictograms provided to aide in medication measurement have also been shown to decrease errors and may be considered as part of discharge instructions.72 The AAP supports policy on the use of milliliter-only dosing for liquid medications used in the home and suggests that standardized delivery devices be distributed from the ED for use with these medications.73 As the body of literature regarding health literacy evolves, further addressing these issues in real time may influence out-of-hospital care.

Summary

Pediatric medication safety requires a multidisciplinary approach across the continuum of emergency care, starting in the prehospital setting, during emergency care, and beyond. Key areas for medication safety specific to pediatric care in the ED include the creation of standardized medication dosing guidelines, better integration and use of information technology to support patient safety, and increased education standards across health care disciplines. The following is a list of specific recommendations that can lead to improved pediatric medication safety in the emergency care setting.

Recommendations

  1. Create a standard formulary for pediatric high-risk and commonly used medications;

  2. standardize concentrations of high-risk medications;

  3. reduce the number of available concentrations to the smallest possible number;

  4. provide recommended precalculated doses;

  5. measure and record weight in kilograms only;

  6. use length-based dosing tools when a scale is unavailable or use is not feasible;

  7. implement and support the availability of pharmacists in the ED;

  8. use standardized order sets with embedded best practice prescribing and dosing range maximums;

  9. promote the development of distraction-free medication safety zones for medication preparation;

  10. implement process screening, such as a 2-provider independent check for high-alert medications;

  11. implement and use CPOE and CDS with pediatric-specific kilogram-only dosing rules, including upper dosing limits within ED information systems;

  12. encourage community providers of children with medical complexity to maintain a current medication list and an emergency information form to be available for emergency care;

  13. create and integrate a dedicated pediatric medication safety curriculum into training programs for nurses, physicians, respiratory therapists, nurse practitioners, physician assistants, prehospital providers, and pharmacists;

  14. develop tools for competency assessment;

  15. dispense standardized delivery devices for home administration of liquid medications;

  16. dispense milliliter-only dosing for liquid medications used in the home;

  17. employ advanced counseling such as teach-back when sharing medication instructions for home use; and

  18. use pictogram-based dosing instruction sheets for use of home medications.

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No more sweet tooth? Scientists switch off pleasure from food in brains of mice


Altering activity in brain’s emotion center can eliminate the natural craving for sweet; findings could inform treatments for eating disorders

New research in mice has revealed that the brain’s underlying desire for sweet, and its distaste for bitter, can be erased by manipulating neurons in the amygdala, the emotion center of the brain. The research points to new strategies for understanding and treating eating disorders including obesity and anorexia nervosa.

Brain illustration

New research in mice has revealed that the brain’s underlying desire for sweet, and its distaste for bitter, can be erased by manipulating neurons in the amygdala, the emotion center of the brain.

The study showed that removing an animal’s capacity to crave or despise a taste had no impact on its ability to identify it. The findings suggest that the brain’s complex taste system — which produces an array of thoughts, memories and emotions when tasting food — are actually discrete units that can be individually isolated, modified or removed all together. The research points to new strategies for understanding and treating eating disorders including obesity and anorexia nervosa.

The research was published today in Nature.

“When our brain senses a taste it not only identifies its quality, it choreographs a wonderful symphony of neuronal signals that link that experience to its context, hedonic value, memories, emotions and the other senses, to produce a coherent response,” said Charles S. Zuker, PhD, a principal investigator at Columbia’s Mortimer B. Zuckerman Mind Brain Behavior Institute and the paper’s senior author.

Today’s study builds upon earlier work by Dr. Zuker and his team to map the brain’s taste system. Previously, the researchers revealed that when the tongue encounters one of the five tastes — sweet, bitter, salty, sour or umami — specialized cells on the tongue send signals to specialized regions of the brain so as to identify the taste, and trigger the appropriate actions and behaviors.

To shed light on that experience, the scientists focused on sweet and bitter taste and the amygdala, a brain region known to be important for making value judgments about sensory information. Previous research by Dr. Zuker, a professor of biochemistry and molecular biophysics and of neuroscience and a Howard Hughes Medical Institute Investigator at Columbia University Irving Medical Center, and others showed that the amygdala connects directly to the taste cortex.

“Our earlier work revealed a clear divide between the sweet and bitter regions of the taste cortex,” said Li Wang, PhD, a postdoctoral research scientist in the Zuker lab and the paper’s first author. “This new study showed that same division continued all the way into the amygdala. This segregation between sweet and bitter regions in both the taste cortex and amygdala meant we could independently manipulate these brain regions and monitor any resulting changes in behavior.”

The scientists performed several experiments in which the sweet or bitter connections to the amygdala were artificially switched on, like flicking a series of light switches. When the sweet connections were turned on, the animals responded to water just as if it were sugar. And by manipulating the same types of connections, the researchers could even change the perceived quality of a taste, turning sweet into an aversive taste, or bitter into an attractive one.

In contrast, when the researchers instead turned off the amygdala connections but left the taste cortex untouched, the mice could still recognize and distinguish sweet from bitter, but now lacked the basic emotional reactions, like preference for sugar or aversion to bitter.

“It would be like taking a bite of your favorite chocolate cake but not deriving any enjoyment from doing so,” said Dr. Wang. “After a few bites, you may stop eating, whereas otherwise you would have scarfed it down.”

Usually, the identity of a food and the pleasure one feels when eating it are intertwined. But the researchers showed that these components can be isolated from each other, and then manipulated separately. This suggests that the amygdala could be a promising area of focus when looking for strategies to treat eating disorders.

In the immediate future, Drs. Zuker and Wang are investigating additional brain regions that serve critical roles in the taste system. For example, the taste cortex also links directly to regions involved in motor actions, learning and memory.

“Our goal is to piece together how those regions add meaning and context to taste,” said Dr. Wang. “We hope our investigations will help to decipher how the brain processes sensory information and brings richness to our sensory experiences.”

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Cometh the cyborg: Improved integration of living muscles into robots


Researchers have developed a novel method of growing whole muscles from hydrogel sheets impregnated with myoblasts. They then incorporated these muscles as antagonistic pairs into a biohybrid robot, which successfully performed manipulations of objects. This approach overcame earlier limitations of a short functional life of the muscles and their ability to exert only a weak force, paving the way for more advanced biohybrid robots.

Object manipulations performed by the biohybrid robots.
 

The new field of biohybrid robotics involves the use of living tissue within robots, rather than just metal and plastic. Muscle is one potential key component of such robots, providing the driving force for movement and function. However, in efforts to integrate living muscle into these machines, there have been problems with the force these muscles can exert and the amount of time before they start to shrink and lose their function.

Now, in a study reported in the journal Science Robotics, researchers at The University of Tokyo Institute of Industrial Science have overcome these problems by developing a new method that progresses from individual muscle precursor cells, to muscle-cell-filled sheets, and then to fully functioning skeletal muscle tissues. They incorporated these muscles into a biohybrid robot as antagonistic pairs mimicking those in the body to achieve remarkable robot movement and continued muscle function for over a week.

The team first constructed a robot skeleton on which to install the pair of functioning muscles. This included a rotatable joint, anchors where the muscles could attach, and electrodes to provide the stimulus to induce muscle contraction. For the living muscle part of the robot, rather than extract and use a muscle that had fully formed in the body, the team built one from scratch. For this, they used hydrogel sheets containing muscle precursor cells called myoblasts, holes to attach these sheets to the robot skeleton anchors, and stripes to encourage the muscle fibers to form in an aligned manner.

“Once we had built the muscles, we successfully used them as antagonistic pairs in the robot, with one contracting and the other expanding, just like in the body,” study corresponding author Shoji Takeuchi says. “The fact that they were exerting opposing forces on each other stopped them shrinking and deteriorating, like in previous studies.”

The team also tested the robots in different applications, including having one pick up and place a ring, and having two robots work in unison to pick up a square frame. The results showed that the robots could perform these tasks well, with activation of the muscles leading to flexing of a finger-like protuberance at the end of the robot by around 90°.

“Our findings show that, using this antagonistic arrangement of muscles, these robots can mimic the actions of a human finger,” lead author Yuya Morimoto says. “If we can combine more of these muscles into a single device, we should be able to reproduce the complex muscular interplay that allow hands, arms, and other parts of the body to function.”

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