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Beyond an ability to merely act, today's medical robotics are increasingly able to sense and “think,” providing for an ever-growing list of applications to which they are applied. While surgical robotics continues to dominate the medical robotics market in terms of revenue, a recent research report has identified rehabilitation robotics as a major component of the market.1

Rehabilitation robotics includes devices such as powered exoskeletons and artificial limbs developed to benefit people affected by, for example, spinal cord injuries, neurodegenerative diseases, and amputations. In terms of number of units sold, rehabilitation and prosthetics robots represent 87 percent of the medical robotics market, which the report predicts will experience a 17 percent compound annual growth, growing from a $3.7B market in 2016 to a $9.3B market in 2022.1

As rehabilitation robotics and prosthetics are increasingly able to sense and “think,” they are, in turn, increasingly able to interact directly with humans — sensing environmental and neural signals and instigating natural movements in response. Such robotic devices involve a confluence of various cutting-edge technologies and are often the fruit of collaborative development efforts. As such, researchers and institutions working in this space may find themselves touching upon many aspects of intellectual property law as they seek to protect and commercialize their efforts.

This article explores trends in rehabilitation robotics and prosthetics by providing examples of research and development efforts. The article reviews different ways in which innovations may be protected as research and development efforts progress and highlights intellectual property considerations relevant to collaborative work.

Recent Advancements in Rehabilitation Robotics and Smart Prosthetics

Recent developments in smart prosthetic and rehabilitative devices have focused on improving human-machine interactions. For example, as described by researchers at Massachusetts Institute of Technology (MIT), “during a standard amputation, nerves are transected without the reintroduction of proper neural targets” and “physiological agonist-antagonist muscle relationships are severed, precluding the generation of musculotendinous proprioception.”2 To overcome this problem, the MIT researchers developed a unique paradigm that establishes an agonist-antagonist myoneural interface (AMI) in the amputee. The AMI enables electromyographic (EMG) signals from muscles surgically grafted within the amputee to be communicated to an external prosthesis, and, in turn, for feedback from the external prosthesis to be communicated to the wearer's peripheral nervous system through functional electrical stimulation (FES) of the grafted muscles. The AMI can thus be considered to be both robot and human.

Expanding upon human-prosthesis interactions, researchers at the University of Houston are using mobile brain-body imaging systems to understand the cortical dynamics of walking.3 The researchers at the University of Houston are working towards the development of a brain-machine interface for prosthetic legs to enable amputees to walk more naturally, particularly on uneven terrain.

Figure 1. Illustration of transected nerves placed in a microchannel array that includes a bidirectional interface to record afferent information of the nerve and to provide efferent stimulus to the nerve once the nerve has regenerated in the microchannel array. The drawing is from U.S. Patent No. 9,474,634.

Such advancements in robotic rehabilitation and prosthetic devices are often brought about over several stages of research and development, each of which may result in the generation of intellectual property and which can relate to subject matter beyond the prosthetic device itself. For example, in a patent application filed by University of Houston, published as U.S. Pat. App. 2015/0012111A1, methods of decoding user intent from brain activity are described. In another example, researchers at MIT recently obtained U.S. Patent No. 9,474,634, which describes methods of neurally controlling a device, an illustration of which is shown in Figure 1. As researchers continue to improve upon and refine human-prosthesis interactions, patent protection can be sought for improvements to a device and to methods that relate to understanding and manipulating human-machine interactions.

Turning to the device itself, a smart prosthesis or a smart rehabilitation device likely includes a number of components that enable it to sense, think, and act. Sensor technology is critical for enabling such devices to function and sense environment. Rehabilitation robotics often include and integrate the information from multiple sensors such as gyroscopes, accelerometers, pressure sensors, encoders, touch sensors, torque sensors, and EMG sensors. Development in sensor technology for robotics is a market unto itself, and despite the wide variety of sensors currently available, new sensors often debut. Active (e.g., powered) prosthetic technology, the current state-of-the-art, relies more and more on EMG signals from an amputee's residual limb to evaluate and control modern prostheses. Innovative hybrid EMG and movement sensors allow the sensors to be embedded in a prosthetic socket and communicate wirelessly with the control circuitry.4

Recently, researchers at Georgia Tech announced the creation of a prosthetic arm driven by ultrasound signals that allows amputees to control each of their prosthetic fingers individually.56 The sensors enable wearers to exert fine motor control over prosthetic fingers through ultrasound signaling to detect which finger the wearer wishes to move and how much force the wearer intends to use.

In addition to new and improved sensors, other components to smart prosthetics that may be patentable include controllers that allow the robotic device to “think.” Smart devices will typically include a microcontroller configured to analyze sensed information and command the device to act in some way in response to the sensed information. Such controllers often make use of data-driven models of an act, such as walking, that is to be performed by the rehabilitative or prosthetic device. For example, researchers at the Biomechatronics Group at MIT under the leadership of Dr. Hugh Herr constructed a neuromuscular model of human walking.7 The model is intended to be used in hardware control for prosthetic devices to minimize the metabolic cost of walking with the prosthetic and to provide the wearer of the prosthetic with increased stability by maximizing agreement with kinetic data.

Figure 2. An example of a musculoskeletal walking model, taken from U.S. Patent No. 9,221,177.

Lastly, the rehabilitative or prosthetic device must “act” in some way to assist the wearer. Such devices may include any number of components to enable the device to move in particular manner. Examples of such components include traditional actuators, such as electric motors, pneumatic actuators, shape memory alloys, and piezoelectric actuators, as well as new, biologically inspired actuators. Examples of such biologically inspired actuators include elastic elements that mimic muscle-tendon units and origami-inspired artificial muscles made from soft materials that are able to lift up to a thousand times their weight.8

Figure 3. A schematic representation of a control system for an amputee. The drawing is from International Pub. No. WO2017/120484.

Examples of patents directed to components of smart prosthetic devices include U.S. Pat. Nos. 9,682,005 and 9,221,177. Elastic element exoskeletons are described in U.S. Pat. 9,682,005, and neuromuscular model-based sensing and control paradigms for a robotic leg are described in U.S. Pat. 9,221,177, an illustration of which is shown in Figure 2. In another example, an international patent application, published as W02017/120484, describes methods and systems for providing proprioceptive feedback to restore lost functionality for limb pathologies. Figure 3 illustrates an example of a control system. As new and improved component devices are developed, patent applications are typically filed on an ongoing basis. As such applications are filed, researchers and technology managers should consider potential markets for commercialization in determining whether to seek patent protection domestically, internationally, or both.

With regard to control systems, in addition to patents, intellectual property protection may also be conferred by way of copyrights. Copyrights provide protection for creative works that are fixed in a tangible form, which includes the software code that controls the robotic prosthesis. A copyright exists automatically upon fixation of the work in a tangible form and provides protection for a term that includes the life of the author plus seventy years. Copyright confers an exclusive right to reproduce the work and to create derivative works.

Figure 4. A powered ankle-foot prosthesis, drawing taken from U.S. Patent No. 8,512,415.

In addition to seeking protection for device components on an individual basis (e.g., a sensor, a controller), it is also possible to pursue patent protection for a device as a whole. In some instances, an invention may include a combination of elements, each of which was independently known, but that, together, form a new article. A powered ankle-foot prosthesis may integrated an electrical motor, springs, force transducers, linear and rotary motion encoders, and a microprocessor in a wearable, autonomous robotic device, an example of which is illustrated in Figure 4 taken from U.S. Patent No. 8,512,415.

The patents and patent publications provided in the examples thus far are, specifically utility patents, which can be obtained to protect new and useful processes, machines, articles of manufacture, or compositions of matter. Indeed, for inventions relating to smart prosthetic and rehabilitative devices, utility patents may offer the most powerful protection — a right to exclude others from making, using, offering for sale, or selling the invention for a term of twenty years from the date of filing the patent application.9 However, design patents may also provide valuable protection and can be considered where an ornamental appearance of a device confers value. Design patent protection is available for articles of manufacture having a unique or distinctive shape or appearance and prevents others from making, using, offering for sale, or selling an article with the claimed design for a period of 15 years (14 years for design patent applications filed before May 13, 2015) from the date of grant.

As researchers and institutions develop new technology relating to robotic devices and methods, ongoing consideration should be given towards protecting intellectual property. While utility patent applications are most typically filed, researchers should also consider other types of intellectual property rights, including copyright for control systems and design patent applications for ornamental features of new devices. In addition, researches should also consider the potential markets for commercialization such that patent filings can be made to protect the inventions internationally, in addition to domestically.

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