Metamaterial Science - From Matter to Virtuality
Digital space is a non-physical realm, so it might come as a surprise when the topic of material science is brought up. The metaverse is virtual and therefore does not consist of physical matter. Physical reality does. But, the virtual reality of the metaverse is (or should be) interoperable with the physical reality and is based on data transfer about objects and actions existing in the physical reality. It is based on a systemic link to the realm of matter, and therefore in the metaverse, there must be a receptive system – operated through an interface – that receives information about operations and behavior of the matter.
So far, users have been able to access virtual reality via visual and auditory interface. Currently, there are developments in the area of haptic interfaces that transfer the information on the tactile sensory spectrum. This is the area of relevance for virtual material science. But firstly, before we come to replicating physicality in the virtual space as a way of descending from non-physicality, let us have a look at the evolution of materials from physicality towards the meta realms.
What Are Metamaterials?
Metamaterials are not found naturally. They are engineered periodic composites created for the purpose of alteration of electromagnetic properties of materials in order to obtain non-natural response. Their properties are derived from internal structure of materials on the micro and nano scale, so not from their chemical composition. Working with the structures instead of chemistry, metamaterials enable properties not possible to create by traditional chemical engineering and conventional technology for material discovery.
Metamaterials hold the potential to precisely control and navigate the course of light within a material. This can be applied in optical systems in reducing their dimensionality to much smaller than the previous ones available. They are used to design unique features for novelty optical hardware or entirely new optical systems. The properties of natural and conventional materials are based on their interaction with electromagnetic radiation (light, radio waves etc.).
The tremendous progress in material science is focused on fine-tuning the characteristics of the metamaterials to create seismic-resistant and radiation-resistant shields. These can be absorbed or deflected by the metamaterials, and because their functioning is way different than typical materials, they can be used to resist natural calamities impacting entire human settlements. Future cities will be constructed with metamaterials to make them responsive and resilient.
Data Transmission and Metaverse Application
Due to the ability of metamaterials to control the wave propagation, data transmission transfer is taken to a new level. Specific types of waves, for instance magneto-inductive waves can be used to carry power in a highly controlled manner. This is relevant for expanding the capacity of electronic gadgets (such as wireless charging) that is simply performed via surface contact and no worrying about alignment of the device. Besides the convenience of wireless charging, this signifies progress in data connectivity which is crucial for the information transfer between various domains and systems – such as physical and virtual reality.
A seamless transfer of large data volumes requires advanced data connectivity. Metamaterials use a chip to process the data transmission, which is the bottomline of system interoperability that exists between physical and informational systems. These are used for constructing physical portals (VR technological devices) from physical to virtual reality.
XR portals and Real-Time Interactive Interfaces
Synthetic environment of XR aims to be highly realistic and immersive, but it will remain non-physical. To interact with this realm to such a degree that it can potentially replicate and partially substitute physical reality, we need advanced technological devices for access. Development of XR depends on both – the material and immaterial. They are connected and should be completely interoperable (currently they are not). It means that both software and hardware are important for the metaverse, yet the developments do not progress at the same speed. Significantly slower development, compared to the boom on the software front, poses limitations for interface design and engineering. The end goal is a realistic virtual experience that transfers the entire sensory spectrum and actions in real time.
Transmitting tactile sensory input via haptic interfaces will also be done via wearable XR devices, just like visuals and audio. Users wearing these devices (headsets, gloves, bodysuits etc.) basically put on wearable electronic systems that enable the access to virtual reality via mapping movements, points of visual focus and other cognitive information that can be translated as an input and transmitted as information to navigate the virtual experience. By using metamaterials to construct the physical portals and devices, we could eventually be able to create a real-time interactive interface. That would mean that the physical and virtual reality would reach complete and seamless correspondence based on data transfer – data originating in both physical and the synthetic realm.
Information given by XR devices is in the form of visual and auditory cues. This information is provided to users through head mount displays and speakers, as well as more subtle cues delivered through haptic actuators. Although most commercial VR products use visual and auditory information, the development of haptic technology has been slow. One reason for this is the use of touchless technology that SRK introduced in 2008. Touchless technology is used on whole-body interfaces like the CDM, which is made up of flexible materials that you wear like gloves. Pressure sensors and sensor boards are integrated into these gloves to measure gesture without physical contact. Haptic technology reads your touch to sense specific sensations you would feel in a virtual space. Sensors detect your motions and physiological state, as well as information about the environment. Actuators convert that data into an artificial sensation so you can enjoy feeling hot or cold using only vibrational input modes. Devices that use cold or hot haptic feedback are also being developed to provide a deeper sense of immersion in a virtual world.
Advanced materials for XR
Most commercially available XR devices are rigid, which makes the experience much less immersive. XR technologies transmit their sensations directly to a user's skin via haptic technology and this creates a new demand for advances in next-gen 'skin' that is soft and skin-like so as to maximize the experience.
Stretchable conductors. Soft conductors are an integral part of soft haptic sensors in virtual reality and augmented reality devices. This type of conductor is usually made from one of two types: carbon nanotubes or graphene. Usually, these conductors are quite elastic, but some may be designed for less stretchability.
Stretchable thermoelectric materials. Thermo-haptic interfaces are able to generate artificial cooling and heating sensations. Cooling is relatively simple because electrically conductive materials such as resistive heating can create a sensation of cooling. However, the ability to cool in a wearable form is challenging. Conventional cooling cycles utilize bulky, complex systems such as refrigeration. Skin-like soft thermoelectric devices that use organic or rigid inorganic materials connected with stretchable serpentine metal conductors represent promising options.
Variable-stiffness materials. One reason why materials can have different stiffness is because of their viscosity. Different substances have different natural viscosities, which means they are able to create different types of resistance. For example, magnetorheological fluids and electrorheological fluids are most often classified as a fluid but only produce these different responses when electromagnetic frequencies are applied.
Soft actuators. Actuators, like rigid actuators, can be found in vibro-haptic interfaces. Rigid actuators are not ideal for augmented reality devices because they may cause discomfort at the skin interface and wearability will also be reduced. Various materials have been explored to develop elastomeric actuators, such as dielectric elastomer actuators that make use of compliant capacitors when sandwiched between compliant electrodes, fluidic elastomers and materials with different elastic moduli. Lastly, stimuli-responsive actuators that respond exclusively to various external stimuli like heat, electric or magnetic fields, and light can be used like liquid crystal elastomers or magnetic responsive material.
Outlook
Researchers are always looking for ways to improve XR devices. One of the things they're currently researching is soft haptic interfaces and sensors, which support flexible electronics. When combined with wearable electronic technology and soft robotic systems, these XR devices offer new solutions in improvements in health care, rehabilitation and medical treatments. More research will be needed to fully understand the fundamental relationship between measurable parameters and haptic perception for immersive devices, but we know that XR devices can completely free users from external hardware when they're embedded within the human body through interfaces with the brain. Such implantable devices will rely critically on the development of advanced materials.
More research is needed to fully understand the fundamental relationship between measurable parameters and structural properties, and their transferability into the XR realm. What this article discussed was more focused on the extraction of the parametric data and design of interfaces. Another step is to analyze what happens once the information arrives in the metaverse. How do these data sets on material structures behave within the virtual realm? How can virtual reality be constructed with it? That is a subject of multi-level system operations and recreate effects of physicality in the metaverse.
title credits: Patakk