The objectives of the Compliant Mechanisms Research Group includes creating compliant mechanism theories and applications that are novel, used by others, and that make a difference for good. Experience suggests that new ideas are more likely to be implemented if they also provide the implementer with a competitive advantage that can come through patent protection. While the majority of research results are in the public domain, some are patented and licensed to companies. The purpose of pursuing patents is not to keep others from using the technologies, but rather to facilitate their use by providing additional value to potential licensees.

This page briefly lists some technologies available for license. Licensing is done through the Office of Technology Transfer. A list of Issued Patents is also available.

The technologies here are listed in the categories listed below:

• Microelectromechanical Systems (MEMS) and Nanoelectromechanical Systems (NEMS)
• Force-Displacement
• Bio Applications
• Power Transmission
• Advanced Bicycle Components
• Other

Microelectromechanical Systems (MEMS) and Nanoelectromechanical Systems (NEMS)

Compliant mechanisms are well-suited for application in the micro and nano size regimes. Advantages include planar fabrication, elimination of assembly, reduction or elimination of wear, and high reliability.

• Spherical Three-degree-of-freedom Platform was created for accurate out-of-plane positioning of microelectromechanical system (MEMS). It has three degrees of freedom that are manifested in three input parameters (the rotation of three spherical slider-cranks) and three output parameters (the height of the platform, and magnitude and direction of the platform tilt). Because the platform can tilt away from the horizontal, the system could be used as an orientable mirror in 3-D optics applications in mirror arrays and sensors. It is also possible to combine spherical bistable mechanisms (described elsewhere) to create a multistable device. Such mechanisms are useful in mirror arrays and sensors. More



• Spherical Bistable Mechanism is an approach to provide accurate, low power mechanisms for the out-of-plane positioning of microelectromechanical system (MEMS). Possible applications include mirror arrays, erectable structures, and optical switching and routing. The SBM uniquely combines two recent advances in MEMS (micro spherical slider-crank mechanism and the Young Mechanism) to provide a device that achieves bistable out-of-plane positioning through the use of compliant mechanisms. More



• Piezoresistive Microdisplacement Transducer (PMT) uses the piezoresistive properties of polysilicon to measure the position of microsystems. The novelty of the technology is its ability to use the bulk properties of the material in various loading conditions rather than being limited to selectively doped features under axial loads. This allows a sensing function to be integrated into mechanical systems without additional components. Possible applications include on-chip systems that require high precision positioning. More



• Piezoresistive Bistable State Sensor is a microelectomechanical system (MEMS) capable of on-chip sensing of bistable mechanism state using the piezoresistive properties of polysilicon. Sensing the state of bistable mechanisms is critical for enabling new applications, including low-power sensing arrays and alternative forms of nonvolatile memory. More



• Carbon Nanotube-based Compliant Mechanism uses carbon nanotubes as the flexible elements in a compliant mechanism. The resulting device is potential building block for many future nanomechanical systems. The intellectual property is joint between MIT and BYU.



• Self-sensing Long-displacement MEMS Device is a high-precision microelectomechanical system capable of accurately sensing the linear displacement of a moving platform. The device also constrain platform motion to the desired direction. Piezoresistivity provides an electrical output that is proportional to the platform displacement. The output signal can be used for feedback control, system diagnostics, or as part of a sensor. More



• Thermomechanical In-Plane Microactuators (TIM) use geometric constraints to amplify small deflections from thermal expansion to achieve large displacements for on-chip actuation. TIMs can be fabricated from a single layer and the design is easily configured for various force outputs. Because the device size, it heats up and cools down quickly, and actuation cycles of less than 50 microseconds have been measured. Patent sold.



• Compliant Bistable Micromechanisms can be fabricated from a single layer. They have two stable equilibrium positions that are maintained without any energy input, and energy is only required to transition between states. Possible applications include microswitches, microrelays, optical switches, micro positioning systems, and others. Patent sold.



• Self-Retracting Fully Compliant Bistable Micromechanisms combine principles of compliant mechanisms, bistable mechanisms, and thermal actuation to provide two distinct stable equilibrium positions. An actuator would cause the transition from the first to the second stable equilibrium positions. When in the second stable position, a voltage can be applied across the device and it will act like a thermal actuator and cause a transition to the first stable equilibrium position. Patent sold.



• Dual Position Linear Displacement Micromechanism provides two distinct positions on a linear path. One configuration allows the transition between the two positions using a single actuation point, thus reducing the number of actuators and die space required. Patent sold.

Force-Displacement

The following technologies use compliant mechanisms to provide unique force-deflection behavior:

• Bistable Mechanisms move between two stable conditions (On and Off positions) and are useful as switches, circuit breakers, clamps, snap hinges, closures, positioning devices, etc. Though they require external force to move from position 1 to 2, no holding energy is required to remain in either position. Other advantages may include simplified fabrication, no required assembly, adaptable, durable, and scalable for a wide range of force and motion requirements. Prototypes have been fabricated in several materials, including microscopic devices constructed from polycrystalline silicon. Plastic prototypes have exceeded a million cycles in durability tests. More



• Ortho-Planar Spring is a thin flat spring whose small central platform moves perpendicular or orthogonal to the fabrication plane. Unlike similar spider-springs or geophones, the platform doesn't rotate so there is no rubbing nor wear. It can be actuated physically or by an electromagnet and used in keyboards, pneumatic valves, electrical contacts, positioners, damping devices, touch probes, speakers, precision antennae, circuit boards, etc. More



• Ortho-Planar ATV Clutch Spring is a configuration of the compliant ortho-planar spring that is particularly well-suited for implementation in continuously variable transmissions, such as the clutch common in all-terrain vehicles and snowmobiles. The ortho-planar spring replaces the traditional coil spring, thus reducing the overall device size and reducing the spinning mass. The spring can be installed in layers, making it easy to tune by adding or removing layers, offering an advantage for high-performance vehicles and for vehicles operating under varying conditions and altitudes. More



• Near-Constant-Force Compression Mechanism use compliant technology to achieve near-constant force over a wide range of deflection. Several configurations have been designed to work over a range of travel patterns. Although constant-force springs have been available for tension applications, no constant-force compression mechanism is known to be on the market, so the opportunities are great. Uses of near-constant-force compression mechanisms might include biasing mechanisms, fitness products, robot end effectors, tool holder, motor brush holder, wear test apparatus, and safety devices.



• Near-Constant-Force Electrical Connectors use compliant technology to maintain constant connection between electrical connections over long periods of time. License has been granted for communication electronics (i.e. cell phones and Palm Pilots&tm;) but license is available for other applications. Advantages are reduced wear, low maintenance, ease of manufacture, reduced part count and cost. The majority of computer hardware and automotive electrical problems arise from faulty electrical contact integrity. The NCF electrical connector improves connections and reliability. Technology licensed to ATL Technology.



• Constant Force Exercise Equipment provides a near-constant force over a range of motion, replacing hundreds of pounds of weight with lighter adjustable compliant mechanism. More



• Surface Morphing Device is manufactured from flat sheets of material and may be mechanically actuated to move between a flat state and a raised state. Electrical actuation of an array of morphing mechanisms would allow new possibilities for reconfigurable user interfaces, or for surface texturing. The design is bistable and can be easily transitioned between its compact, flat state, and its morphed, actuated state. More



• Compliant Rolling-contact Element (CORE) can produce large angle deflection between two rigid bodies. Due to the rolling contact that takes place, these mechanisms are excellent in compression and produce little or no friction, thus greatly reducing wear on the mechanism. Potential applications include devices that require large rotation with minimal wear, high precision, or minimal space (such as hand-held electronics - e.g. clamshell phones, PDAs, etc.)

Bio Applications

Motion in nature is often achieved using compliance. Consider a human heart, a humming bird's wing, or the motion of an eel. These and other highly evolved compliant systems are complex but compact and efficient. It only makes sense that as we learn more of nature, and our capabilities for performing complex engineering analysis and design improve, more compliant mechanism designs will emerge in bioengineering fields.

• Artificial Spinal Disc
uses a compliant mechanism to closely mimic the range of motion and the force-deflection behavior of the human spinal disc. The device has no articulating joints, thus reducing or eliminating wear. Technology licensed to Crocker Spinal Technologies.


• Micro Injector
is a MEMS based microinjector. It consists of two or more mechanisms for constraining an individual cell and a movable needle for injecting charged molecules such as DNA or RNA into the cell. Each mechanism is fabricated from planar layers of polysilicon. The needle operates on the principle of electrostatic attraction and repulsion. Technology licensed to Nanoinjection Technologies, LLC.

Power Transmission

Compliant mechanisms have proven useful in transmitting power in drive trains. In addition to the devices listed below, a few related technologies are listed in under the "Force-Displacement" category above.

• Centrifugal Clutches made as compliant mechanisms eliminate numerous segments, springs, pins, etc. Flexible segments are designed into the single moving part so that when the hub (driven by a motor) spins the clutch up to speed, centrifugal force causes the heavy segments to engage the drum and drive the machinery. Special qualities include smoother engagement, higher torque, ease of adaptability and replacement, and potential for reduced cost. Small and medium horsepower applications include go-karts, mini-bikes, trimmers, tillers, chain saws, chippers, amusement rides, agriculture and industrial machine couplings. More



• Overrunning Clutches, with or without centrifugal throw out, provide torque in one direction but freewheel in the other. They are used for one- and two-way rotation, as in pull-starts for small engines, bicycle free wheels, fishing reels, gear drives, winches, conveyors, elevators, counters, collators, feed mechanisms, and many other machines. As with other compliant clutches, advantages include reduced part count, low cost, low wear at high speeds, and efficient load transfer. More

Advanced Bicycle Components

Compliant mechanism bicycle components offer potential weight savings, increased performance, and a unique look and feel.

• Bicycle Brakes of compliant design provide parallel motion with minimal parts, have visual appeal, and are preferred by experts for their strength, superior control, even wear, and reduced noise. More



• Compliant Bicycle Derailleur equals the performance of a regular bicycle derailleur with decreased weight. Compliant components integrate the functions of springs and rigid links.



• Continuously Variable Transmission using compliant mechanisms. Exclusive license granted.



• Bicycle Freewheel - see Overrunning Clutches in the Power Transmission section.

Other

• Lamina Emergent Torsional Joints provide hinge-like motion in devices fabricated from flat sheets of material. They have application in packaging, microelectromechanical systems, and devices made from sheet metal or other sheet materials. More



• Multi-layered Compliant Mechanisms and Method of Manufacture provides an approach for fabricating high-volume compliant mechanisms by stamping layers from a layer of thinner material and stacking the layers together. This is particularly useful for compliant mechanisms made of metals.



• Compliant Grippers and pliers can be produced from an injection-mold process and constructed of one piece, significantly reducing assembly requirements. Compliant mechanism grippers do not use pins or springs yet function exactly like traditional grippers. The grippers can be used in a variety of applications: in photo labs, in chemistry labs, with electrical equipment, etc.