Modern Day Telepathy: Advances in Brain-to-Brain Communications

Catalyst Volume 8

Is it possible to create and communicate through a mental link without using sensory networks? Telepathy, a common theme in science fiction, involves transferring thoughts from one person to another. As a result of recent developments in neuroscience and technology, scientists have discovered a new form of communication that does not require us to speak, listen, type, or text.

Previously, there have been attempts to achieve the goal of brain-to-brain communication, but all successful attempts have been invasive methods, which have limited practicality. Dr. Alvaro Pascual-Leone, the director of the Berenson-Allen Center for Noninvasive Brain Stimulation at Beth Israel Deaconess Medical Center, had a similar vision of creating a way to for people to communicate without being constrained by physical abilities, such as talking and listening. However, he wanted to implement a non-invasive method for brain-to-brain communication in order to create a more practical system. He assembled an international team of researchers specializing in neuroscience and robotic engineering to create this form of telepathic communication using a brain-computer interface, allowing humans to send messages to computers using non-invasive brain-computer interactions.¹ On September 3, 2014, his team was able to successfully demonstrate direct brain-to-brain communication between human subjects on different continents. In order to facilitate this direct communication, the team combined several forms of brain technology.

One brain technology the researchers incorporated was the electroencephalogram. Electroencephalography (EEG) is a non-invasive form of a brain-computer interface that records brain activity. When brain cells communicate, they send impulses to each other. EEG detects these impulses through electrodes that are placed directly onto the scalp. The electrodes are connected to a recording device that displays the recorded brain activity as waves.² EEG is often used clinically to examine the brain during seizures, monitor the depth of anesthesia, and inspect the brain for damage.

The second technology the team used was transcranial magnetic stimulation (TMS), which uses magnetic fields to stimulate nerve cells in the brain and is often used to treat depression. The process of stimulating nerve cells involves placing a large electromagnetic coil against the scalp near the forehead and producing an electric current using the electromagnet.³ Because of the current, neurons fire and become more active. This can cause different reactions including muscle twitching or seeing flashes of light.

While EEG and TMS have different medical uses, Dr. Pascual-Leone integrated the two technologies to create a groundbreaking communication system that relies on EEG to read the original message in the sender’s brain and a TMS system to relay the information into the receiving brain. This brain-to-brain communication experiment involved four volunteers—one in India and three in France. The volunteer in India sent the messages, and the three volunteers in France received them.¹

The sender was connected to an EEG-based brain-computer interface, and he transmitted the words “hola” and “ciao” to the recipients who received the message through a TMS-based receiver.¹ The EEG read the sender’s brain activity and converted the letters to binary code. The transmission system used a wireless EEG that sent the data to a computer for brain-computer interface processing. The message was then sent to a TMS computer in France through the Internet. Using electromagnetic stimulation, the TMS relayed the messages to the receivers by stimulating their brains to see flashes of light in their periphery called phosphenes.¹ The recipients do not directly receive the thought itself in their minds; instead, they are stimulated in the form of a phosphene code and consciously interpret stimulation. These flashes are similar to Morse code in that the participants can understand the sequences and decode the information into the greetings that were sent to them. All three recipients translated the message successfully. A second experiment was done in the same manner as the previous one, except the message was sent between participants in Spain and France. The error rate for this experiment was about 15%. Human error in the participants decoding the message that was sent to them accounted for 11% of the total error.¹

These experiments proved to be an enormous advance in using properties of the brain and new technology to discover new ways of communication. However, the experimenters agree that there still remains much research to be done to make the system of brain-to-brain communication more efficient and applicable. Further developments of this communication system need to make the technology more accessible and user-friendly. The sizeable challenges of reducing EEG and TMS to a small device as well as the complexity of both instruments make brain-to-brain communication seem like an unattainable goal.

The prospect of developing direct brain-to-brain interfaces raises questions on how much it can change the way people communicate in society as well as the future of written and oral communication. This technology brings us closer to a form of communication similar to telepathy, which has only been depicted in science fiction. However, one major difference is that this technology uses the Internet as an intermediate. In science fiction, telepathy is often used to send private messages from one person to another without the chance of someone else reading or hearing the message, a characteristic that makes telepathy very appealing. If the Internet is used as an intermediate, however, the information sent through this interface will not be as private or secure as people expect telepathy to be. If this brain-to-brain technology lacks the private aspect of telepathy, will it provide any benefits when compared to our current forms of communication? In its current state, users must also take the extra effort in learning how to decode phosphene signals, an additional step that makes this brain interface a more unattractive option.

Although questions of practicality discourage the commercialization of Dr. Pascual-Leone’s invention, his experiments have made significant headway into direct brain-to-brain communication. The success of this technology depends on how efficient and user-friendly scientists can make this device. Many concepts, including early computers and space exploration, were seen as implausible or impractical in their nascency but developed into commonplace technologies. Whether or not this invention is currently practical, it is amazing how scientific research has brought the seemingly outlandish idea of telepathy closer to reality.

References

1. Grau, C. et al. Plos One. [Online] 2014. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0105225  (accessed Oct. 13, 2014).
2. National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/003931.htm (accessed Oct. 13, 2014).
3. Johns Hopkins Medicine. http://www.hopkinsmedicine.org/psychiatry/specialty_areas/brain_stimulation/tms/ (accessed Oct. 13, 2014).

The Bright Future of Solar Energy

Catalyst Volume 8

Renewable energy is the dream of countless environmentalists and active citizens. Adopting hybrid electric vehicles and domestic sources of sustainable energy are some of the goals of renewable energy. The increasing price of energy derived from crude oil and concerns regarding energy security have stimulated investments in sustainable resources such as solar energy.

The search for and extraction of oil are negatively impacting the environment around oil platforms. Offshore drilling platforms report spills every year that kill an estimated 315 thousand birds per platform.¹ Additionally, the waste fluids ejected from the drilling process harm marine life that rely on filter feeding; these pollutants then travel up the food chain in a process called biomagnification.^2-4 Research and development efforts in renewable energy sources promise to minimize these harmful practices by reducing society’s dependence on oil.

One such alternative to oil-derived energy lies in residential and commercial photovoltaic solar panels that convert sunlight into electric current. Depending on the weather, the sun provides between 3.6—6 kWh/m² (kilowatt-hours per square meter) per day in the U.S.5 Homeowners are beginning to capitalize on this source by installing residential, small-scale “rooftop panels,” which are labeled as photovoltaic (PV) systems. These systems work to create electric current by harnessing the excitation of electrons from sunlight. These systems are becoming commonplace as their cost continues to decrease. In 2011, the cost of installing PV systems was 11—14% lower than that in 2010, and in 2013 prices were even lower.⁶

The most widely adopted material in these products is silicon, a material known for its conductivity. Development in conducting materials and manufacturing methods has greatly accelerated since the first application of silicon, improving energy collection. Now, total global grid-connected systems produce seven million kW.7 As the average American home uses between 2—5 kW per year, this grid system can support two to three million U.S. homes.8 A second viable option for solar energy is Concentrated Solar Power (CSP). Known as “power towers,” CSP uses mirrors to concentrate the sun’s rays, generating enough power to heat water and operate a turbine. Water is not the only fluid utilized: in a parabolic mirror system, oil is heated to 400 °C to convert water into steam via subsequent heat transfer.⁹

CSP plants are expanding globally; they are expected to produce a total of 5000 MWh (megawatt-hour) by 2015. This is an increase from the 2011 figure of 1000 MWh. As one might expect, these towers are set to be installed in sunlight-rich areas, with the majority of this planned construction taking place in California. Towers will also be installed in China, Israel, South Africa, and Spain.⁷ Typical CSP systems today can generate one MWh of electricity for every 4—12 square meters of land space, which, according to the Royal Academy of Engineering Ingenia, “can continuously and indefinitely generate as much electricity as any conventional 50 MW coal- or gas-fired power station.”¹⁰ This is relatively small, given that the average U.S. residential home occupies about 405 square meters. The average 1000 MW U.S. coal-fired power plant requires 1—4 square kilometers of land space, translating into 6—18 GWh (m2/gigawatt-hours), or 4—20 square meters per GWh. However, including the amount of land needed for mining and waste disposal, this figure can include an upper limit of 33 m2/GWh.¹¹ This factor of land efficiency leads to these newly installed CSP plants to produce one kWh worth of electricity for $0.10—0.12, given the costs of installation and maintenance as well as other fixed and variable costs. In Houston, Texas, rates for oil-derived electricity can range from $0.08—0.15/kWh, which makes CSP a very competitive alternative.¹⁰

Opposing arguments based on the high cost of photon-collecting technology and the intermittency of solar rays are losing ground. In the U.S. alone, the PV market has grown considerably. For example, California experienced a 39% growth in residential PV system installations in the fourth quarter of 2012 (Fig. 1).¹² Thus far, the cost of these systems has declined over 30% in the past few decades, and the U.S. Department of Energy’s (DOE) SunShot Vision Study is attempting to further reduce costs by 75%. With this initiative, the DOE plans to “meet 14% of U.S. electricity needs via solar energy by 2030 and 27% by 2050.”¹³ It is believed that this goal will be possible once solar electricity generation reaches the cost of $0.06/kWh, near the range of current fossil-fuel based generation methods.¹³ The SunShot Vision Study has implemented a “Rooftop Solar Challenge” aimed at improving the logistical requirements of installations in order to apply its initiative to states across the U.S.

Applications for solar energy can range from using solar cookers with the CSP model to portable solar chargers for personal electronics. These forms of energy can be scaled to any size, and their full integration into society is only hindered by the current dependence on oil. To make energy production sustainable, solar technology must be further developed and implemented. Statistical models need to be considered, academic and industrial research needs to be funded, and a united effort in adopting these technologies needs to take place. Significant progress has been made in homeowner PV system adoption and the DOE’s SunShot Vision, which serve as testaments to the viability of a sustainable energy economy. When comparing the advantages of oil against the advantages of solar energy, it is clear that solar energy has the potential to provide more efficient and environmentally friendly results. These alternatives still need technological advancement, proper location, and governmental support; once these are completed, solar alternatives will be able to meet our energy needs. Although we as a society may find ourselves too dependent on oil, there is hope for a more sustainable, responsible, and environmentally friendly world.

References

1. Tasker, M. L. et al. The Auk. 1984, 101, 567-577.
2. Wiese, F.K. Marine Pollution Bulletin. 2001, 42, 1285-1290.
3. Wiese, F.K.; Robertson, G. J. Journal of Wildlife Management. 2004. 68, 627-638.
4. Ocean Discharge Criteria Evaluation;  General Permit GMG290000; US EPA: 2012; 3. http://www.epa.gov/region06/water/npdes/genpermit/gmg290000_2012_draft/ocean_discharge_criteria_evaluation.pdf (accessed Feb. 1, 2014).
5. George Washington University GW Solar Institute. How much solar energy is available? http://solar.gwu.edu/FAQ/solar_potential.html (accessed Feb. 1, 2014).
6. Chen, A. Lawrence Berkeley National Laboratory. The installed price of solar photovoltaic systems in the U.S. continues to decline at a rapid pace. http://newscenter.lbl.gov/news-releases/2012/11/27/the-installed-price-of-solar-photovoltaic-systems-in-the-u-s-continues-to-decline-at-a-rapid-pace/ (accessed Feb. 1, 2014).
7. Hamrin, J.; Kern, E. Grid-Connected Renewable Energy: Solar Electric Technologies; United States Agency of International Development (USAID): Washington, D. C. http://www.energytoolbox.org/gcre/mod_5/gcre_solar.pdf (accessed Oct. 28, 2013).
8. Solar Energy Industries Association. Solar Energy Facts: Q3 2013. http://www.seia.org/research-resources/solar-industry-data (accessed Feb. 1, 2014).
9. Concentrating Solar Polar (CSP) technologies. http://solareis.anl.gov/guide/solar/csp/ (accessed Feb. 3, 2014).
10. Müller-Steinhagen, H.; Trieb, F. Concentrating solar power: a review of the technology. Royal Academy of Engineering, Ingenia. 2004, 18, 43-50.
11. Fthenakis, V.; Kim, H. C. Renew. Sust. Energ. Rev. 2009, 37, 1465-1474.
12. Solar Energy Industries Association. U.S. Solar Market Insight 2013. http://www.seia.org/sites/default/files/4Y8cIWF6ps2013q1SMIES.pdf?key=58959256 (accessed Nov. 10, 2013).
13. U.S. Department of Energy. SunShot Initiative.  http://www1.eere.energy.gov/solar/sunshot/about.html (accessed Nov. 10, 2013).
14. U.S. Department of Energy. Updated capital cost estimates for utility scale electricity generating plants. U.S. Energy Information Administration: Washington, DC, 2013. http://www.eia.gov/forecasts/capitalcost/pdf/updated_capcost.pdf  (accessed Nov. 7, 2014).

The Reality of Virtual Reality

Catalyst Volume 8

People experience the world around them, what we call “reality,” by receiving sensory input and processing these messages. Sources of sensory stimulus are greatly varied and include anything from sound waves picked up by your ears to the feeling of wearing socks. Because the basis of perception is founded on stimulation, manipulation of these inputs can effectively enable people to experience false sensations. A virtual world indistinguishable from reality—perfectly stimulating all senses—is the end-goal of researchers developing virtual reality interfaces.

Virtual reality (VR) refers to computer-generated simulation of a realistic or imaginary world that uses visual, tactile, and auditory cues to manipulate the user's sensations and perceptions. While VR interfaces usually include head-mounted displays that provide visual input, more sophisticated devices for simulating senses of touch, taste, smell, and sound are being researched. An important goal of VR research is attaining the ability to provide a highly realistic environment in which individuals can interact with their surroundings and receive sensory feedback. Unfortunately, due to the limitations of computing power and research in the field of VR, a program inducing complete immersion into the virtual worlds is not yet possible.

Although VR seems to be a technology borrowed from science fiction novels, it has actually existed in some fashion for eight decades. In 1929, Edward Link invented the first flying simulator, which used pneumatics to mimic aerial maneuvers and provided haptic feedback to the user. The Link Trainer, which initially gained popularity as an amusement park ride, later became a standard training module for U.S. pilots during World War II.¹ The Link Trainer is a very primitive example of VR, as it leaves much to imagination; pilots would be hard pressed to believe they were actually within the cockpit of an aircraft during a dogfight and not in a cramped box, rocking back and forth. However, since its creation, the Link Trainer has promoted the idea that simulators could be utilized to recreate situations that would otherwise be difficult to experience.

The advent of computers initiated an explosion of advanced VR interfaces such as head mounted displays (HMDs) that allow the user to interact with the virtual world and receive enhanced sensory information. In 1991, Virtuality Group developed the 1000CS gaming system, which was a pioneer in the field of head tracking and enabled players to turn their heads to view their surroundings within the games they were playing.² The 1000CS was an important first step for commercially available VR technology. Modern HMDs are much less bulky than their predecessors, less prone to causing neck cramps due to their lighter weight, and more responsive to rotation. Recent advances in virtual reality focus on providing as realistic an environment as possible. Higher resolution screens and faster computers are becoming cheaper to produce and more widely available, spurring the growth of VR.

While most interfaces prioritize visual and audio simulation, technologies are being developed that will be able to stimulate touch, taste, and smell to provide a highly life-like world. Researchers at the Universities of York and Warwick have presented a prototype of the Virtual Cocoon, a helmet that uses tubes, fans, and a high definition (HD) screen to fully immerse the user in what the team calls “Real Virtuality.”³ Another recent advance from the University of Singapore used “non-invasive electrical and thermal stimulation … [to] recreate the taste of virtual food and drinks.”⁴ Such technologies could lead to a perfect virtual environment that stimulates all of the senses. Additionally, this research introduces exciting possibilities such as virtually sampling a dish before ordering it at a restaurant or experiencing the feeling of snow on a hot summer day.

The last decade has seen both great advances in VR technologies and expansion into a wide range of practical fields such as military training.⁵ Although simulators have been used by the military since the simple Link Trainer in 1929, new methods of virtual simulation have greatly increased the diversity and immersion of training available. Soldiers can be placed in various virtual scenarios and learn the tactics and skills necessary in real combat, including developing assault plans on military targets, managing disaster and field casualties, and adapting to new environments.^5,6 While it cannot replace field experience, VR serves as a useful tool to augment their training.

There are many projected uses for VR in the field of medicine as well. An experiment led by Dr. Patrice Crochet of La Conception Hospital in Marseille tested whether surgeons using a VR surgical training simulator could improve the quality of their surgical skills. Their findings indicated that VR training improved surgeons’ dexterity, supporting the claim that VR could potentially serve as a medical training tool.⁷ With the high number of annual medical malpractice deaths, using VR to provide doctors with practical experience is most definitely a useful tool.

Perhaps the most anticipated application of VR is its extension into video games and other multimedia. The Oculus Rift, an HMD currently in development, is a highly anticipated game system that incorporates HD graphics with high-fidelity head tracking to create a unique gaming experience.^8,9 Combined with omnidirectional treadmills and directional audio, players may soon be able to engage in a highly realistic environment. Virtual controllers such as the Leap Motion—which uses sensors to process hand and finger motions as input data—are also being incorporated for further immersion and interactive capabilities. These VR technologies are not only limited to video games; virtual tourism or impossible real-world experiences such as flying could be simulated.

With ever-increasing computer processing speeds and extremely high resolution 8K displays in development, the future of VR holds great promise. Currently, VR is proving invaluable to military and medical training. A major limitation of VR is its inability to create perfect, interference-free environments due to inadequate hardware and software capabilities. However, these obstacles will be overcome as VR technology advances. Perhaps one day it will be impossible to distinguish between simulated reality and reality itself.

References

1. Van Embden, E. Rare flight trainer can be found at Millville Army Airfield Museum / Link Trainer one of 5 working models in world. The Press of Atlantic City, Feb. 23, 2008, p. C1.
2. Davies, H. Dr. Waldern’s dream machines: arcade thrills for spotty youths today, but revolutionary tools for surgeons and architects tomorrow, says the pioneer of virtual reality. http://www.independent.co.uk/life-style/ the-hunter-davies-interview-dr-waldernsdream-machines-arcade-thrills-for-spottyyouths-today-but-revolutionary-tools-forsurgeons-and-architects-tomorrow-says-thepioneer-of-virtual-reality-1506176.html (accessed Jan. 17, 2015.)
3. First virtual reality technology to let you see, hear, smell, taste, and touch. www.sciencedaily. com/releases/2009/03/090304091227.htm (accessed Jan. 17, 2015).
4. National University of Singapore. Simulator recreates virtual taste online.http://www.sciencedaily.com/ releases/2014/01/140102114807.htm (accessed Oct. 31, 2014).
5. Bymer, L. Virtual reality used to train soldiers in new training simulator. http://www.army.mil/ article/84453/ (accessed Jan. 17, 2015).
6. Virtual reality army training. http://www.vrs. org.uk/virtual-reality-military/army-training. html# (accessed Oct. 31, 2014).
7. Crochet, P. et al. Ann. Surg. 2011, 253, 1216-1222.
8. Corriea, A. Oculus Rift HD drops you into a world so real it hurts. http://www.polygon. com/2013/6/14/4429086/oculus-rift-hd-e3 (accessed Nov. 9, 2014).
9. Oculus Rift. https://www.oculus.com/ (accessed Jan. 17, 2015).

Honey, Where's My Supersuit? New Underwater Technology Emerges

Catalyst Volume 8

A plot line from a comic book unfolds as scientists and artists alike take inspiration from superheroes to develop technology that could allow humans to further explore ocean environments. Despite mankind's attempts to explore the world’s oceans since the 18th century, 95% of this vast, watery expanse remains a mystery.¹ Heavy oxygen tanks and burdensome helmets are still needed to get to moderate depths, while the deep ocean lies mostly uncharted. Without super strength or super flexibility, divers turn to the next best superpower: the ability to breathe underwater.

Deep-sea exploration necessitates the design of equipment that functions under extreme conditions, challenge that seemingly only a technological genius like Iron Man could conquer. After all, the self-made billionaire created his own armor to escape captivity. A suit similar to Iron Man’s was needed for an expedition to an abandoned shipwreck off the coast of the Antikythera islands in the fall of 2014.² In order to reach the 55 foot-deep shipwreck, the Canadian company HUBLOT developed the Exosuit, a 550 pound atmospheric diving system (ADS) that allows explorers to dive deeper and longer.³ The full metal suit combined with semi-closed rebreathing technology pragmatically favored function over form. A semi-closed rebreather involves a constant flow rate of oxygen, and any excess oxygen that is not inhaled is released back into the water in the form of small bubbles.⁴ Paired with the suit is a remotely operated vehicle (ROV) that takes high-quality photos in any lighting, which is useful in deep waters.³

Upon first glance, the suit seems incredibly cumbersome with its daunting rigidity and thick, pipe-like legs. However, many smaller components like foot pads and rotary joints make the suit more flexible; this allows the user to access previously uncharted deep waters with robotic efficiency.⁴ As the underwater version of Iron Man’s suit, the Exosuit has an exterior that can withstand extremely high pressures. The sturdy exterior, paired with the ROV camera, will allow scientists to identify new species of marine life, especially those that are visible due to phospholuminescence. The dangers of the depths unknown explored with a one-of-a-kind suit and camera seem to come right off the page of one of Stan Lee’s comics. Tony Stark would definitely approve.

Although Iron Man is revered for his cleverness and intelligence, the best superhero inspiration for diving technology is Aquaman and his ability to breathe freely underwater. Many innovators, including South Korean designer Jeabyun Yeon, have tried to mimic the ease with which Aquaman is able to breath below the surface. In January 2014, Yeon created a device that would allow divers to breathe underwater with only a piece of standalone equipment attached to the mouth, leaving behind the typical mask, alternate air source, air gauge, and other equipment necessary for a normal dive.⁵ Called the Triton, this gill-like mouthpiece extracts oxygen from water and compresses it into small storage tanks located on either side of a mouthpiece.⁵ While swimming, users would only need to bite into the mouthpiece for oxygen to begin flowing. Although aesthetically pleasing, this design received a lot of negative attention from scientists and scuba divers that prevented it from gaining funding from investors and traction in the media. For the design to be feasible, there must be a pump that can bring 24 gallons of water through its filtering system per minute; however no such pump is available at present.⁵ The Triton also does not account for possible oxygen toxicity, the condition where high pressures of stored oxygen can cause convulsions and potentially be fatal.⁶ Yeon originally intended for the design to be a revolutionary breakthrough in the diving community, but now the Triton is displayed on his website as a “product innovation studio project.”⁷ Although his project had little impact on the diving community, other scientists continue to find ways to bring Aquaman to life.

The University of Denmark are doing just that with the “Aquaman” crystal, marking a shift from developing wearable technology to researching materials science. In October of 2014, the university released news of the “Aquaman” crystal, a cobalt-based crystalline material that can absorb, store, and release oxygen without deteriorating or changing form through processes known as known as chemisorption and desorption. These processes involve multiple chemical transformations that produce a denser form of oxygen gas that can be stored in a compact form without causing toxicity to the user.⁸ As a result, this inorganic material possesses properties that rival diving equipment in both size and efficiency, potentially allowing divers to have almost superhuman, Aquaman-like characteristics when underwater. A powerful example of the crystal’s abilities is the absorption of the amount of oxygen in an average-sized room using just 10 liters of the material.⁸ Although the size of a scuba tank varies with the type of dive, the fact that the “Aquaman” crystal can hold three times as much pressurized pure oxygen as a conventional tank of the same size will inevitably decrease the weight of equipment that divers need underwater. Professor Christine Mackenzie, a scientist on the team, claims that only few grains of the crystal are needed to sustain a full trip underwater.⁸ The team is currently working on ways to access the stored oxygen, possibly by directly inhaling the crystal or by using a specialized tank.⁸ By eliminating or reducing the size of the tank, the “Aquaman” crystal would allow divers to explore hard-to-reach areas and put them in even closer contact with the organisms they are examining.

The parallels between scuba equipment and superhumans like Iron Man and Aquaman show how far underwater diving equipment has progressed. Even far-fetched concepts like the Triton give a glimpse of what the future may look like. The ability to breathe underwater opens the door to new discoveries both by granting divers to either dive more flexibly at moderate depths or get a more personal glimpse into the deep ocean. Scuba equipment continues to play a major role in how we understand one of the earth’s most mysterious ecosystems, especially in the face of climate change. What was once written off as superhuman and fantastic might just develop into our reality.

References

1. National Oceanic and Atmospheric Administration. http://www.noaa.gov/ocean.html (accessed Oct. 12, 2014).
2. Wallace, R. ‘Iron Man’ suit allows divers to reveal more of Antikythera shipwreck. http://www.sciencetimes.com/articles/677/20141012/iron-man-suit-allows-divers-to-reveal-more-of-antikythera-shipwreck.htm (accessed Oct. 12, 2014).
3. The Exosuit. http://www.amnh.org/exhibitions/past-exhibitions/the-exosuit/the-exosuit (accessed Oct. 12, 2014).
4. Scuba diving. http://www.scubadiving.com/training/basic-skills/are-you-ready-rebreathers (accessed Oct. 28, 2014).
5. ‘Triton’ oxygen mask claims to draw oxygen from water while you swim. http://www.huffingtonpost.co.uk/2014/01/17/triton-oxygen-mask_n_4615558.html (accessed Oct. 12, 2014).
6. Patel, D. N. et al. JIACM 2003, 4, 234-237.
7. Yeon. Yanko Design. http://www.yankodesign.com/2014/01/03/scuba-breath/ (accessed Oct. 23, 2014).
8. Sundberg, J. et al. Chem. Sci. 2014, 5, 4017-4025.