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STMicroelectronics, (NYSE: STM) has integrated machine-learning technology into its advanced inertial sensors to improve activity-tracking performance and battery life in mobiles and wearables.

The LSM6DSOX iNEMO sensor contains a machine-learning core to classify motion data based on known patterns. Relieving this first stage of activity tracking from the main processor saves energy and accelerates motion-based apps such as fitness logging, wellness monitoring, personal navigation, and fall detection.

“Machine learning is already used for fast and efficient pattern recognition in social media, financial modelling, or autonomous driving,” said Andrea Onetti, Analog, MEMS and Sensors Group Vice President, STMicroelectronics. “The LSM6DSOX motion sensor integrates machine-learning capabilities to enhance activity tracking in smartphones and wearables.”

Devices equipped with ST’s LSM6DSOX can deliver a convenient and responsive “always-on” user experience without trading battery runtime. The sensor also has more internal memory than conventional sensors, and a state-of-the-art high-speed I3C digital interface, allowing longer periods between interactions with the main controller and shorter connection times for extra energy savings.

The sensor is easy to integrate with popular mobile platforms such as Android and iOS, simplifying use in smart devices for consumer, medical, and industrial markets.

The LSM6DSOX is in full production and available now, priced from $2.50 for orders of 1000 pieces.

Further technical information:

The LSM6DSOX contains a 3D MEMS accelerometer and 3D MEMS gyroscope, and tracks complex movements using the machine-learning core at low typical current consumption of just 0.55mA to minimize load on the battery.

The machine-learning core works in conjunction with the sensor’s integrated finite-state machine logic to handle motion pattern recognition or vibration detection. Customers creating activity-tracking products with the LSM6DSOX can train the core for decision-tree based classification using Weka, an open-source PC-based application, to generate settings and limits from sample data such as acceleration, speed, and magnetic angle that characterize the types of movements to be detected.

Support for free-fall, wakeup, 6D/4D orientation, click and double-click interrupts allows a wide variety of applications such as user-interface management and laptop protection in addition to activity tracking. Auxiliary outputs and configuration options also simplify use in optical image stabilization (OIS).

By Maria Vetrano

With over 25 years of experience in the technology industry, Sri Peruvemba, CMO of CLEARink Displays, is a longtime advocate of electronic display technology. During his presentation at FLEX and MEMS & Sensors Technical Congress 2019, February 18-21 in Monterey, Calif., Peruvemba will explain recent innovations in electronic paper (ePaper) that will open new applications to reflective displays for the first time.

SEMI: ePaper has been around for more than a decade. How has it evolved for wearables and mobile devices?

Peruvemba: ePaper in its current form provides a reflective display that is low power and sunlight-readable to applications such as eReaders and electronic shelf labels (ESLs), both of which are in mass production. There is a much larger opportunity, however, for reflective displays that offer color and video atop the traditional benefits of ePaper. Now possible through electrophoretic total internal reflection (eTIR) – which we have termed ePaper 2.0 – is a low-power technology that allows devices to work for days instead of hours. eTIR offers sunlight readability as well as full color and video-level switching speeds, which satisfies the diverse requirements of wearables and mobile devices.

New electrophoretic total internal reflection (eTIR) display technology uses the charged particles in a fluid to modulate the total internal reflected light from the optical structures incorporated into its novel reflector film. Image courtesy of CLEARink Displays.

SEMI: How do you define a “reflective display?”

Peruvemba: A display that reflects external light to its advantage is a reflective display. This includes the display that uses ambient light rather than a backlight and one that uses the sun rather than fights it.

SEMI: Where is there a larger opportunity for reflective displays that offer color and video over the traditional benefits of ePaper?

Peruvemba: While most of us are familiar with ePaper in applications such as eReaders and wearables that need sunlight readability, there is an untapped market in the wearables space for applications that require internet browsing and color, even video, displays. ESLs are a good example. Retailers are no longer content to show prices. They also want to show specials, display color ads, and run video and animation to enhance product differentiation. Displays in tablets, digital signage and automotive are additional targets.

SEMI: How large is the opportunity?

Peruvemba: The electronic display industry has been trying to build reflective displays that are low-power color and video for many years but without success. Hence, the opportunity is in the tens of billions of U.S. dollars in outdoor signs, automotive displays, tablets, wearables, shelf labels and dozens of others products.

SEMI: What will it take for manufacturers to migrate from LCD or OLED to eTIR?

Peruvemba: The good news is that implementation is pretty much the same as with the LCD or OLED displays currently in use. The interfaces, connections and form factors remain form-, fit-, function-compatible. Only the software/waveforms and drive voltages will change/reduce. This allows the manufacture of our tech., ePaper 2.0, on the old LCD lines that are already in use. You can literally go back and forth between ePaper 2.0 and LCD on a day-to-day basis. This differs from other eTIR implementations, which require new dedicated manufacturing lines that cost tens to hundreds of millions of dollars.

SEMI: Are there other emerging markets that are particularly well-matched to eTIR?

Peruvemba: Tablet devices designed for long use on a single charge, mobile devices including wearables for outdoor applications, Internet of Things (IoT) devices that need high ambient readability, and very low-power and unobtrusive displays in home or office settings represent other emerging markets.

SEMI: What technical obstacles have hindered ePaper in certain markets – and how do you overcome those obstacles?

Peruvemba: Bringing a display technology to market is not only about solving technical and process hurdles. It is also about finding the right one percent of the applications that your technology can uniquely address. Success requires developing the ecosystem of subcomponent suppliers and peripheral technology providers (like touch and front lights). Partnering with the display fabs that can mass-produce your technology is another important step.

With most emerging technologies, the pursuit of the right customer is the bigger challenge, but for us it has been getting the product into production. Fortunately, we already have customers that have invested in the company and have committed to product volume, so they get early access to our technology.

SEMI: What would you like FLEX and MSTC attendees to take away from your presentation?

Peruvemba: Now just months away from deploying our eTIR technology as ePaper 2.0, we welcome partnership inquiries as we seek to implement eTIR across a range of previously unserved and underserved display markets.

Sri Peruvemba will present ePaper 2.0 — Creating New Markets at FLEX/MSTC on Tuesday, February 19 at 2:45 pm

Register today to connect with him at the event. To learn more about CLEARink Displays, click here.

MSTC FLEX 2019 is organized by MEMS & Sensors Industry Group (MSIG) and FlexTech.

Leti, an institute of CEA-Tech, has developed a novel retinal-projection concept for augmented reality (AR) uses based on a combination of integrated optics and holography. The lens-free optical system uses disruptive technologies to overcome the limitations of existing AR glasses, such as limited field-of-view and bulky optical systems.

TVs and smartphones that project digital images emit light all around them, as quasi-isotropic sources. Because the images are projected generally over the air without directivity, many viewers see the same image. In typical AR glasses, images are transmitted close to the eyes (high directivity) by a microdisplay that includes an optical system and an optical combiner.

These microdisplays create a small near-to-eye image, which is transformed by the optical system, enabling the user to see it despite the short focusing distance. The combiner superimposes the digital image to the viewers’ vision of the real environment.

CEA-Leti’s innovation is a transparent retinal-projection device that projects various light waves to the eyes from a glass surface. Images are formed in the retina by the interference of light waves, which eliminates the need for optical systems or combiners. The light propagating in the air doesn’t form an image until it interferes precisely in the retina.

CEA-Leti presented its results Feb. 6 at SPIE Photonics West 2019 in a paper titled “Integrated Optical Network Design for a Retinal Projection Concept Based on Single-Mode Si3N4 Waveguides at 532 nm”.

The project focused on the design and numerical simulations of integrated Si3N4 optical components and the optical circuit at λ = 532 nm. It required building blocks for designing an optical integrated circuit capable of creating an array of emissive points. Starting with single-mode waveguides to efficiently transport light around the circuit, many other components were designed to manipulate light in different locations. Components for extracting the light, such as diffraction gratings, were also designed and simulated. The team minimized losses of different parts of the circuit, such as waveguide-bending areas, to increase energy efficiency of the system.

CEA-Leti’s integration of the device and its use of a holographic layer also allow creation of compact AR glasses with a larger field-of-view than existing systems, while the transparent retinal projection device allows ambient light to pass through the device for enhanced AR applications.

“Combining integrated optics and holography is a new research area for the scientific community developing display applications,” said Basile Meynard, a Ph.D. student and lead author of the paper. “It is also a way to imagine a display device that works more as a data transfer system than as an imaging system.”

The novel approach will require further development before it reaches the commercialization stage. In the medium to long term, the retinal projection concept is expected to support more compact and higher virtual-image quality applications similar to existing AR glasses.

This research project builds on CEA-Leti’s many years of development of micro-displays for near-to-eye displays, such as organic LED technologies (OLED) and liquid crystal devices (LCD). More recently, the institute has made significant strides in the field of inorganic LED display manufacturing.

“Our teams are continuously looking for potential disruptive technologies that could pave the way to new families of display devices down the road,” said Christophe Martinez, optical senior scientist and project leader in Leti. “The investigation on retinal displays is part of this exploration of future optical solutions.”

Researchers from the University of Houston have reported significant advances in stretchable electronics, moving the field closer to commercialization.

Researchers from the University of Houston have reported significant advances in the field of stretchable, rubbery electronics. Credit: University of Houston

In a paper published Friday, Feb. 1, in Science Advances, they outlined advances in creating stretchable rubbery semiconductors, including rubbery integrated electronics, logic circuits and arrayed sensory skins fully based on rubber materials.

Cunjiang Yu, Bill D. Cook Assistant Professor of mechanical engineering at the University of Houston and corresponding author on the paper, said the work could lead to important advances in smart devices such as robotic skins, implantable bioelectronics and human-machine interfaces.

Yu previously reported a breakthrough in semiconductors with instilled mechanical stretchability, much like a rubber band, in 2017.

This work, he said, takes the concept further with improved carrier mobility and integrated electronics.

“We report fully rubbery integrated electronics from a rubbery semiconductor with a high effective mobility … obtained by introducing metallic carbon nanotubes into a rubbery semiconductor with organic semiconductor nanofibrils percolated,” the researchers wrote. “This enhancement in carrier mobility is enabled by providing fast paths and, therefore, a shortened carrier transport distance.”

Carrier mobility, or the speed at which electrons can move through a material, is critical for an electronic device to work successfully, because it governs the ability of the semiconductor transistors to amplify the current.

Previous stretchable semiconductors have been hampered by low carrier mobility, along with complex fabrication requirements. For this work, the researchers discovered that adding minute amounts of metallic carbon nanotubes to the rubbery semiconductor of P3HT – polydimethylsiloxane composite – leads to improved carrier mobility by providing what Yu described as “a highway” to speed up the carrier transport across the semiconductor.

CEA-Leti today announced it has prototyped a next-generation optical chemical sensor using mid-infrared silicon photonics that can be integrated in smartphones and other portable devices.

Mid-IR chemical sensors operate in the spectral range of 2.5µm to 12µm, and are considered the paradigm of innovative silicon-photonic devices. In less than a decade, chemical sensing has become a key application for these devices because of the growing potential of spectroscopy, materials processing, and chemical and biomolecular sensing, as well as security and industrial applications. Measurement in this spectral range provides highly selective, sensitive and unequivocal identification of chemicals.

The coin-size, on-chip, IoT-ready sensors prototyped by Leti combine high performance and low power consumption and enable such consumer uses as air-quality monitoring in homes and vehicles, and wearable health and well-being applications. Industrial uses include real-time air-quality monitoring and a range of worker-safety applications.

Mid-IR optical sensors available on the market today are typically bulky, shoebox-size or bigger, and cost more than €10,000. Meanwhile, current miniaturized and inexpensive sensors cannot meet consumer requirements for accuracy, selectivity and sensitivity. While size and price are not the most critical concerns for industrial applications, bulky and costly optical sensors represent a major barrier for consumer applications, which require wearability and integration in a range of portable devices.

CEA-Leti presented its R&D results Feb. 05 at SPIE Photonics West 2019 in a paper titled “Miniaturization of Mid-IR Sensors on Si: Challenges and Perspectives”.

“Mid-IR silicon photonics has enabled creation of a novel class of integrated components, allowing the integration at chip level of the main building blocks required for chemical sensing,” said Sergio Nicoletti, lead author of the paper. “Key steps in this development extend the wavelength range available from a single source, handling and routing of the beams using photonic-integrated circuits, and the investigation of novel detection schemes that allow fully integrated on-chip sensing.”

CEA-Leti’s breakthrough combined three existing technologies necessary to produce on-chip optical chemical sensors:

  • Integrating a mid-IR laser on silicon
  • Developing photonic integrated circuits (PICs) in the mid-IR wavelength range, and
  • Miniaturizing a photoacoustic detector on silicon chips.

“While other R&D efforts have had similar results, our project’s key achievement is the use of tools and processes typical of the IC and MEMS industries,” Nicoletti said. “Our focus on the choice of the architectures and processes, and the specific linkage of the series of steps also were critical to developing this optical chemical sensor, which CEA-Leti is now realizing as demo prototypes.”

Water molecules distort the electrical resistance of graphene, but a team of European researchers has discovered that when this two-dimensional material is integrated with the metal of a circuit, contact resistance is not impaired by humidity. This finding will help to develop new sensors -the interface between circuits and the real world- with a significant cost reduction.

The many applications of graphene, an atomically-thin sheet of carbon atoms with extraordinary conductivity and mechanical properties, include the manufacture of sensors. These transform environmental parameters into electrical signals that can be processed and measured with a computer.

Due to their two-dimensional structure, graphene-based sensors are extremely sensitive and promise good performance at low manufacturing cost in the next years.

To achieve this, graphene needs to make efficient electrical contacts when integrated with a conventional electronic circuit. Such proper contacts are crucial in any sensor and significantly affect its performance.

But a problem arises: graphene is sensitive to humidity, to the water molecules in the surrounding air that are adsorbed onto its surface. H2O molecules change the electrical resistance of this carbon material, which introduces a false signal into the sensor.

However, Swedish scientists have found that when graphene binds to the metal of electronic circuits, the contact resistance (the part of a material’s total resistance due to imperfect contact at the interface) is not affected by moisture.

“This will make life easier for sensor designers, since they won’t have to worry about humidity influencing the contacts, just the influence on the graphene itself,” explains Arne Quellmalz, a PhD student at KTH Royal Institute of Technology (Sweden) and the main researcher of the research.

The study, published in the journal ACS Applied Materials & Interfaces, has been carried out experimentally using graphene together with gold metallization and silica substrates in transmission line model test structures, as well as computer simulations.

“By combining graphene with conventional electronics, you can take advantage of both the unique properties of graphene and the low cost of conventional integrated circuits.” says Quellmalz, “One way of combining these two technologies is to place the graphene on top of finished electronics, rather than depositing the metal on top the graphene sheet.”

As part of the European CO2-DETECT project, the authors are applying this new approach to create the first prototypes of graphene-based sensors. More specifically, the purpose is to measure carbon dioxide (CO2), the main greenhouse gas, by means of optical detection of mid-infrared light and at lower costs than with other technologies.

In addition to the KTH Royal Institute of Technology, the companies SenseAir AB from Sweden and Amo GmbH from Germany are likewise participants in the CO2-DETECT project, as is the Catalan Institute of Nanotechnology (ICN) from Barcelona.

Laser systems specialist LPKF Laser & Electronics, based in Hannover, Germany has added a foundry service for thin glass substrates to its product portfolio. The company recently introduced the Laser-Induced Deep Etching technology, or LIDE for short, a process for the precise and highly efficient manufacturing of through-glass vias (TGV) and other deep micro features in thin glass substrates. The LIDE process is able to overcome past limitations in glass drilling and micro machining as it combines very high productivity and low manufacturing cost with the superior quality of a direct data process, forgoing masks or photo processing.

With the introduction of its new independent foundry service, LPKF is hoping to make the LIDE technology available on a much wider scale, covering both prototyping and experimental applications as well as scalable mass production capacity. The service is aimed at the manufacturing of glass substrates for advanced IC and MEMS packaging as well as micro-machining of spacer wafers,microfluidics and other specialty glass applications. LPKF’s new foundry service is located at its corporate headquarters and will operate under the company’s Vitrion brand name.

Established in 1976, LPKF Laser & Electronics manufactures laser systems used in circuit board prototyping, microelectronics fabrication, solar panel scribers, laser plastic welding systems and recently added a foundry service for thin glass substrates used in electronics packaging. LPKF’sworldwide headquarters is located in Hannover, Germany and its North American headquarters resides in Portland, OR.

A NIMS-led research group succeeded in developing a high-quality diamond cantilever with among the highest quality (Q) factor values at room temperature ever achieved. The group also succeeded for the first time in the world in developing a single crystal diamond microelectromechanical systems (MEMS) sensor chip that can be actuated and sensed by electrical signals. These achievements may popularize research on diamond MEMS with significantly higher sensitivity and greater reliability than existing silicon MEMS.

Micrographs of the diamond MEMS chip developed through this research and one of the diamond cantilevers integrated into the chip. Credit: NIMS

MEMS sensors–in which microscopic cantilevers (projecting beams fixed at only one end) and electronic circuits are integrated on a single substrate–have been used in gas sensors, mass analyzers and scanning microscope probes. For MEMS sensors to be applied in a wider variety of fields, such as disaster prevention and medicine, their sensitivity and reliability need to be further increased. The elastic constant and mechanical constant of diamond are among the highest of any material, making it promising for use in the development of highly reliable and sensitive MEMS sensors. However, three-dimensional microfabrication of diamond is difficult due to its mechanical hardness. This research group developed a “smart cut” fabrication method which enabled microprocessing of diamond using ion beams and succeeded in fabricating a single crystal diamond cantilever in 2010. However, the quality factor of the diamond cantilever was similar to that of existing silicon cantilevers because of the presence of surface defects.

The research group subsequently developed a new technique enabling atomic-scale etching of diamond surfaces. This etching technique allowed the group to remove defects on the bottom surface of the single crystal diamond cantilever fabricated using the smart cut method. The resulting cantilever exhibited Q factor values–a parameter used to measure the sensitivity of a cantilever–greater than one million; among the world’s highest. The group then formulated a novel MEMS device concept: simultaneous integration of a cantilever, an electronic circuit that oscillates the cantilever and an electronic circuit that senses the vibration of the cantilever. Finally, the group developed a single crystal diamond MEMS chip that can be actuated by electrical signals and successfully demonstrated its operation for the first time in the world. The chip exhibited very high performance; it was highly sensitive and capable of operating at low voltages and at temperatures as high as 600°C.

These results may expedite research on fundamental technology vital to the practical application of diamond MEMS chips and the development of extremely sensitive, high-speed, compact and reliable sensors capable of distinguishing masses differing by as light as a single molecule.

A research study on low noise and high-performance transistors led by Suprem Das, assistant professor of industrial and manufacturing systems engineering, in collaboration with researchers at Purdue University, was recently published by Physical Review Applied.

The study has demonstrated micro/nano-scale transistors made of two-dimensional atomic thin materials that show high performance and low noise. The devices are less than one-hundredth of the diameter of a single human hair and could be key to innovating electronics and precision sensing.

Many researchers worldwide are focusing attention on building the next generation of transistors from atomic scale “exotic” 2D materials such as molybdenum di-selenide. These materials are promising because they show high-performance transistor-action that may, in the future, replace today’s silicon electronics. However, very few of them are looking at yet another important aspect: the inherent electronic noise in this new class of materials. Electronic noise is ubiquitous to all devices and circuits and only worsens when the material becomes atomic thin.

A recent study conducted by Das’ research team has systematically shown that if one can control the layer thickness between 10 and 15-atomic thin in a transistor, the device will not only show high performance — such as turning the switch “on” — but also experience very low electronic noise. This unique finding is essential to building several enabling technologies in electronics and sensing using a number of emerging 2D materials. This research is a comprehensive effort of a previous finding, where Das’ team conducted the first study on noise in MoSe2 transistors.

A team of researchers at the New York University Tandon School of Engineering and NYU Center for Neural Science has solved a longstanding puzzle of how to build ultra-sensitive, ultra-small electrochemical sensors with homogenous and predictable properties by discovering how to engineer graphene structure on an atomic level.

Finely tuned electrochemical sensors (also referred to as electrodes) that are as small as biological cells are prized for medical diagnostics and environmental monitoring systems. Demand has spurred efforts to develop nanoengineered carbon-based electrodes, which offer unmatched electronic, thermal, and mechanical properties. Yet these efforts have long been stymied by the lack of quantitative principles to guide the precise engineering of the electrode sensitivity to biochemical molecules.

Davood Shahrjerdi, an assistant professor of electrical and computer engineering at NYU Tandon, and Roozbeh Kiani, an assistant professor of neural science and psychology at the Center for Neural Science, Faculty of Arts and Science, have revealed the relationship between various structural defects in graphene and the sensitivity of the electrodes made of it. This discovery opens the door for the precise engineering and industrial-scale production of homogeneous arrays of graphene electrodes. The researchers detail their study in a paper published today in the journal Advanced Materials.

Graphene is a single, atom-thin sheet of carbon. There is a traditional consensus that structural defects in graphene can generally enhance the sensitivity of electrodes constructed from it.  However, a firm understanding of the relationship between various structural defects and the sensitivity has long eluded researchers. This information is particularly vital for tuning the density of different defects in graphene in order to achieve a desired level of sensitivity.

“Until now, achieving a desired sensitivity effect was akin to voodoo or alchemy — oftentimes, we weren’t sure why a certain approach yielded a more or less sensitive electrode,” Shahrjerdi said. “By systematically studying the influence of various types and densities of material defects on the electrode’s sensitivity, we created a physics-based microscopic model that replaces superstition with scientific insight.”

In a surprise finding, the researchers discovered that only one group of defects in graphene’s structure — point defects — significantly impacts electrode sensitivity, which increases linearly with the average density of these defects, within a certain range. “If we optimize these point defects in number and density, we can create an electrode that is up to 20 times more sensitive than conventional electrodes,” Kiani explained.

These findings stand to impact both the fabrication of and applications for graphene-based electrodes. Today’s carbon-based electrodes are calibrated for sensitivity post-fabrication, a time-consuming process that hampers large-scale production, but the researchers’ findings will allow for the precise engineering of the sensitivity during the material synthesis, thereby enabling industrial-scale production of carbon-based electrodes with reliable and reproducible sensitivity.

Currently, carbon-based electrodes are impractical for any application that requires a dense array of sensors: The results are unreliable due to large variations of the electrode-to-electrode sensitivity within the array. These new findings will enable the use of ultra-small carbon-based electrodes with homogeneous and extraordinarily high sensitivities in next-generation neural probes and multiplexed “lab-on-a-chip” platforms for medical diagnostics and drug development, and they may replace optical methods for measuring biological samples including DNA.