Khalil Najafi
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Thermoelectric Module for Energy Generation and Cooling Applications
6650 – A highly efficient small-scale thermoelectric module for both energy generation and cooling applications has been developed at the University of Michigan. Current thermoelectric devices are inefficient—with efficiencies of around 6% at best. Even though thermoelectric materials have advanced significantly in recent years, challenges preclude their use in high performance devices.... Read More
An Active Diode Full-Wave Charge Pump
6512 – A lowest voltage stage driven active diode full-wave charge pump with load selection has been developed at the University of Michigan for structural health monitoring applications. Bridge health monitoring sensors can be powered by vibration harvesters actuated by non-periodic low-acceleration suspension bridge movement. However, this type of harvester output requires an interface circuit... Read More
Low-Noise Large Dynamic Range Multi-Axis Accelerometers Made From Thick Silicon
6986 – Capacitive accelerometers and inertial measurement units are used in a wide range of applications such as smart phones and tablets, aerospace navigation, and industrial testing and measurement. By 2019, the revenue for microelectromechanical system (MEMS) accelerometers and gyroscopes is expected to reach $5 billion, and miniaturization is the critical product feature [1]. Several device... Read More
Actuation and Sensing Platform for Sensor Calibration and Vibration Isolation
6571 – A micro-platform with integrated multi-axis actuation and position sensing capabilities for in-situ calibration of long-term scale-factor drifts in the output signals of micromachined inertial measurement units, has been developed at the University of Michigan. The use of micromachined inertial measurement units, such as MEMS accelerometers and gyroscopes, in high accuracy strategic and... Read More
Three Dimensional Microstructures and Fabrication Process of Micro-scale Navigation Grade Rate Integrating Gyroscope for GPS-free Guidance
6500 – Recent advances in micro-electromechanical system (MEMS) technologies resulted in the successful commercialization of high-performance sensors and actuators in a variety of areas such as motion sensing, wireless communication, energy harvesting, and healthcare. The performance of most MEMS sensors and actuators are limited by materials along with their structures and because of their low... Read More
Mechanical Amplifier for Energy Transducer Devices
5960 – Researchers at the University of Michigan have developed a mechanical amplifier that amplifies the displacement amplitude or generated force of an energy transducer system. The amplifier is targeted towards applications such as vibration-energy harvesters and electromechanical sensors and actuators, and can be integrated with a variety of transducers types such as electromagnetic,... Read More
Electromagnetic Energy Transducer for Energy Harvesting or Mechanical Actuation
5959 – Researchers at the University of Michigan have developed an electromagnetic transducer for converting kinetic energy to electrical energy, or electrical energy to mechanical displacement. The transducer is targeted towards operation under harsh conditions such as high centrifugal acceleration, high axial and radial static displacements, and tilting movements. The transducer can be embedded in... Read More
MEMS Electrostatic Micro-Hydraulic Systems for Sensing and Actuation
5564 – Researchers at the University of Michigan have developed micro-hydraulic structures for high performance sensing and actuation. Hydraulic or pneumatic structures are extensively used in systems where amplification of force, or deflection, is needed. Operation of such systems is based on uniform distribution of pressure over an incompressible liquid filling two connected chambers. And... Read More
Three-Dimensional MEMS Sensors and Actuators and Microsystems
5563 – Scientists at the University of Michigan have developed hair-like sensors targeted towards MEMS sensor, actuator, and microsystem applications. Through a combination of mechanical sensing, local chemo-electric transduction, and sophisticated signal processing, biological hair sensors provide unique capabilities such as sensitivity and response that are unmatched by other sensor structures. ... Read More
Single-side Microelectromechanical Capacitive Accelerometer and Method of Making Same
1644d2 – UM File # 1644d2 Background Accelerometers are often utilized in various applications including navigation, guidance, microgravity measurements, seismology and platform stabilization. Conventional accelerometers are fabricated by either surface- or bulk-micromachining. The surface-micromachined devices are fabricated on a single silicon wafer, but bear low sensitivity and large noise... Read More
Fused Silica Microsensors, Microactuators, Packaging, and Microsystems
5196 – MEMS inertial measurement units (IMUs) are currently manufactured using hybrid integration at the system level. While co-fabrication of components has been proposed, it has yet to produce a useful implementation of IMUs. Major challenges include large component size, inadequate performance, device coupling, and conflicting process and package requirements for accelerometers, gyroscopes... Read More
Probes with Deployable Sites
5052 – Electrical interfaces to biological tissue, whether to read out biological signals, to artificially stimulate nerves or muscles, or to deliver drugs is a long persecuted field of high interest. Many modern probes consist of a needle like shank hosting sites for recording or stimulation. The sites can be electrodes, openings of optical waveguides, chemical sensors, out- and inlets of fluid... Read More
A Micromachined In-plane Silicon Accelerometer with a Combined Surface and Bulk Micromachining Technology
2491 – Applications of microaccelerometers cover a wide range from those which require low/medium sensitivity sensors, to those used in inertial navigation/guidance systems, seismometry, or microgravity measurements, which demand high sensitivity with very low noise floor. Among various sensing methods, the capacitive sensing technique has recently gained attention as it provides high... Read More
Fabrication of Out-of -plane Curved Surfaces Utilizing RIE Lag
2191 – Several MEMS applications, including high-performance electrostatic actuators and optical components, require a non-planar surface topography. For example, an electrostatically-driven parallel-plate actuator can provide a much larger vertical deflection with a low voltage if the drive electrode is curved. In this structure, a large force is created around the edges of the diaphragm... Read More
Low-Temperature Localized Wafer Bonding with Photosensitive Bezocyclobutene (BCB) and 3D MEMS (Microelectromechanical Systems) Structure Fabrication
2122 – Many emerging MEMS require the construction of complex 3-dimensional (3D) microstructures, which typically utilizes wafer bonding, including Si-Si fusion, Si-Si anodic, and Si-glass anodic bonding. Many of these processes are associated with high temperatures, difficulty in precise machining, and may be time and labor intensive to be cost effective for commercial production. As such,... Read More
Wafer-Level Vacuum Packaging Technology for MEMS
2457 – Low-cost vacuum packaging has become one of the most important challenges in the MEMS industry for a number of emerging applications including resonant sensors and radiofrequency MEMS. Some essential features of a MEMS package include small size, vacuum/ hermetic capability, integrated sealed feedthroughs, wafer level processing, stability in harsh environmental conditions, and low cost.... Read More
Power Scavenger Architecture for Low-Frequency Ambient Vibration
4362 – Wireless sensors, implantable devices, and other low-power gadgets typically obtain operational power in one of two ways: 1) by using electrochemical batteries or micro fuel cells and 2) by energy scavenging from environmental sources such as ambient heat, light, and vibration. Although electrochemical batteries and fuel cells can provide more power, they are not desirable for some... Read More
An Electromagnetic MicroPower Generator for Low-Frequency Environmental Vibrations by Using Mechanical Frequency Up-Conversion
2714 – Self-powered remote-controlled systems are frequently powered via batteries or fuel cells, or by drawing energy from ambient sources such as heat or light. Energy scavenging has recently become popular owing to its ability to produce clean power for sustained period of time. Among various energy scavenging sources, vibration has gained attention due to its abundance and several suitable... Read More
Compact, Modular Assembly and Packaging of Multi-Substrate Microsystems
2669 – Packaging is one of the main components of microfabricated systems. While there has been much development regarding manufacturing of dense packages for various multi-chip module technologies, none provides the flexibility, modularity, and small size needed for a microsystem containing substrates with sensors, actuators, and circuits fabricated using different technologies. Modularity and... Read More
Frequency Shift Keying Demodulation Methods for Wireless Biomedical Implants
2525 – Wireless transfer of power and data is often achieved via inductive link between two magnetically-coupled coils. One application which requires transfer of large amounts of data to interface with many conduits include biomedical implants such as for cochlear implants and visual prostheses. For such applications, increased rate of data transfer and minimal power consumption are paramount... Read More
MEMS Micropump
2342 – Micropumps are used in microfluidics systems to accurately deliver small volumes of fluid. For gas pumping applications, actuation is commonly accomplished by piezoelectrically- or electrostatically-driven membranes, which is often limited in their membrane displacement volume and requirement of high drive voltages. Recently, curved electrodes have been proposed to achieve larger... Read More
Field-assisted Bonding of Insulator to Eutectic Solder
2288 – One of the essential processes shared by many microelectromechanical systems (MEMS) is packaging. Packaging is a less-explored aspect of a microsystem, but can significantly affect overall device performance and cost. To minimize damage to the final microdevice, new packaging technologies that can be applied at the wafer level, before the device is separated from the host wafer, have... Read More
A Folded-Electrode Structure for Electromechanical Capacitive Accelerometers
1644 – Accelerometers are often utilized in various applications including navigation, guidance, microgravity measurements, seismology and platform stabilization. Conventional accelerometers are fabricated by either surface- or bulk-micromachining. The surface-micromachined devices are fabricated on a single silicon wafer, but bear low sensitivity and large noise floor. Some high resolution... Read More
Vacuum Encapsulation Technique Utilizing Electroplated Films
2278 – Micromachined devices and MEMS have made significant progress during the past two decades with many prototype devices demonstrated for applications including pressure sensors, optical communication systems, and biomedical microsystems. While these applications require different devices and signal processing circuits, they all share the need for reliable, stable, and low-power packaging... Read More
Wafer-Level Fabrication of MEMS and Solid-State Devices Via Solder Bonded or Parylene Bonded and Thinned Bulk Piezoelectric Substrate
4440 – There are various possible applications of “smart” materials such as piezoelectric materials, both in micro-electro-mechanical systems (MEMS) devices and in solid state devices. Typical fabrication methods for piezoelectric thin films involve great challenges such as a need for high temperature processing, propensity of stress-induced cracking in the piezoelectric thin films, limited film... Read More