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.

Collaborative Work: Identifying Each Party's Inventive Contributions

As medical technology is multidisciplinary, medical technology companies frequently collaborate with outside entities such as research institutions or other technology companies. For example, researchers at the Wyss Institute for Biologically Inspired Engineering at Harvard University teamed up with ReWalk Robotics Ltd. to design and market soft robotic exosuits having compact actuators for individuals with mildly or moderately impaired movement ability. (10) Such collaborative arrangements typically include intellectual property licenses, funding agreements, and joint development agreements. These agreements (or contracts) serve to define each party's role in the collaborative project and to identify the relevant pre-collaboration intellectual property owned by each party. In this context, three intellectual property considerations should be addressed: inventorship, ownership, and sharing of information.

Inventorship is determined by the “claims” of a patent application, so that any individual who has contributed to the complete mental conception of the subject matter of any claim needs to be named as an inventor. Simply taking part in the reduction to practice of the invention does not make an individual an inventor. However, the conception must be complete so that any person skilled in the art would be able to reduce the invention to practice using no more than routine experimentation. Joint inventorship occurs when the ideas of two or more individuals are combined to form the invention. Per statute, inventors may apply for a patent jointly even though (1) they did not physically work together or at the same time, (2) each did not make the same type or amount of contribution, or (3) each did not make a contribution to the subject matter of every claim of the patent.

An assessment of inventorship should be completed before any patent application is filed to mitigate issues over patent rights. In addition, if, during the course of developing a product for commercial release, there is an improvement that is not described in a previously filed patent application or patent, a new patent application can be filed on the improvement. This can be critical because, often, it may be the improvement that is the most important or only intellectual property that ultimately can be protected.

Understanding Who Owns the Intellectual Property

Under U.S. law, an inventor owns the rights in a patentable invention until the inventor transfers ownership to another party. Although employment circumstances may result in ownership by an employer, it is best that a company have employees assign their rights in future inventions to the company when they become employees. Otherwise, if a patent is found to be owned by an inventor, the inventor can independently license or assign her rights and collect proceeds from any license or assignment without accounting to the company or other inventors named on the patent. Even if the inventor had agreed to assign the rights under an employment agreement with the company, failure to actually assign those rights and have the assignment recorded in the U.S. Patent and Trademark Office may enable the inventor to assign the rights to a third party. This may result in a breach of the employment contract but leave intact an inventor's actual assignment of rights to a third party. Preferably, the language of an employment agreement will make present assignments of future inventions, e.g., by specifying that the employee “hereby assigns his or her rights” in any invention conceived while employed.

In collaborative work, patent applications and patents may be jointly owned among multiple parties. Assignments of rights by inventors having obligations to assign their rights to two different companies will cause the resulting patent application or patent to be jointly owned by both companies. Certain consequences of joint ownership should be understood when entering into collaboration agreements. Absent agreement to the contrary, a joint owner of a patent may make, use, sell, or license the patented invention without consent of and without accounting to any other joint owner. In addition, under U.S. law, all joint owners of a patent must be joined as parties to a suit for infringement. Agreements underpinning collaborative work arrangements can be drafted, or amended, to address the issues.

Identifying Intellectual Property and Sharing of Information

Several different types of agreements are often associated with intellectual property of medical technology companies. A nondisclosure agreement (NDA) can be an important tool in protecting confidential information from being disclosed to the public before any inventions have been filed as patent applications. An NDA is a written agreement to keep confidential the information to be shared. Often, parties enter into an NDA before negotiating the collaboration agreement, to allow confidential sharing of know-how and technology while working out the agreement. Regardless of any confidentiality agreement, it is recommended that a patent application be filed before disclosing a pre-collaboration invention to another party. In this way, the intellectual property can be identified in a listing of patents and patent applications at the outset of the collaboration, and the filing date of the listed patent or patent application will help prove prior possession of the subject matter disclosed therein.

Patents and patent applications can be licensed on an exclusive or nonexclusive basis. An “exclusive” license generally means that there is only a single licensee. A “nonexclusive” license implies multiple, or an open-ended number of, possible licensees. Both types of licenses are useful for medical technology companies, and further explanation of licenses is beyond the scope of this article.


The coming years promise to deliver many exciting developments in the field of medical robotics, particularly as the level of sophistication of human-robotic interfaces continues to grow and as the availability of new sensors, actuators, and control systems for rehabilitative and prosthetic robotics continues to expand. As researchers and institutions continue to develop in this space, they should be mindful of seeking protection for their intellectual property throughout the course of development of new products and throughout collaborative efforts.

This article was written by Kristen K. Salvaggio, Associate, and Alexander Adam, Associate, at Hamilton Brook Smith Reynolds. Boston, MA. For more information, Click Here .