wearables

Air pollution is one of the grand challenges facing the entire planet — from the wealthiest nations to the least developed. The World Health Organization reports that nine out of 10 people breathe air containing high levels of pollutants, and that polluted air takes over seven million lives annually through stroke, heart disease and respiratory ailments.As a result, the world is thirsty for reliable, high-performing chemical and environmental sensors that can provide previously unavailable real-time awareness of environmental conditions. On one level, this seems like a relatively simple step, given that smartphones are already equipped with miniaturized sensing technologies that can monitor our living environment and activities.While highly desirable, embedding air pollution sensors in common mobile and wearable devices has not been feasible previously because the necessary trade-offs between high performance and miniaturization have made it impossible.This situation drove a CEA-Leti team to develop a novel generation of fully integrated optical chemical sensors that leverage MEMS technologies. The team successfully merged multiple functionalities on the same chip, using integrated optics and photonics, fluidics, acoustics and electromechanical transduction. How did the team overcome significant technical obstacles to design a proof-of-concept device that senses multiple environmental pollutants — housed in a minimal hardware footprint?Advancing Chemical Sensor Capabilities with Silicon Featuring high selectivity, real-time performance, and fully reversible capabilities, optical chemical sensors are perfect candidates for industrial, environmental and biomedical applications. Consequently, in recent years, worldwide R D initiatives have invested substantial effort to improve them.R D programs have focused particularly on the mid-infrared (Mid-IR) wavelength range (2.5 - 12 µm) — also known as the molecule fingerprint region, which provides a unique combination of fundamental absorption order-of-magnitude bands and unambiguous identification of specific chemicals. A multitude of molecules generate strong and distinct absorption lines in the Mid-IR, providing a foundation for accurate spectroscopic detection. Traditionally, however, these sensors have required large and expensive lenses for infrared (IR) light, making them too big and costly for resource-constrained wearables and mobile devices.Fortunately, recent advances in integrated silicon photonics and quantum cascade laser (QCL) technologies have spurred investigation of new chemical sensor architectures. Richard Soref, a research professor at the University of Massachusetts Boston’s department of engineering, introduced the extension of Near-IR technology into the longer-wave Mid-IR infrared region in 2006. Soref’s concept showed that highly sensitive and selective gas sensors could be fabricated on planar substrates at low cost by co-integrating silicon MEMS, group IV photonics, and specifically designed III-V hetero-structures.While this approach showed promise, it preceded the widespread availability of most mobile devices and wearables. Foreseeing today’s proliferation of those devices, CEA-Leti developed the different building blocks required to implement these concepts in real devices.A New Concept of Integrated OpticsLeveraging these interesting findings, the institute developed a new combination of integrated optics and multiple sensor functions on a single chip: QCL sources, a photo-acoustic (PA) cell, and a mid-IR photonic integrated circuit (PIC) combiner. Their integration on a planar substrate (Figure 1) helped to achieve higher performance, new capabilities, and higher reliability at lower cost, all in a smaller package (less than a 1 cm3 or smaller than a 1-cent coin) with reduced weight and power consumption (less than 100 mJ per measurement). Figure 1: Fully integrated optical sensor (Courtesy: CEA Leti) This configuration represents a multi-gas-detection enabler. The PIC replaces costly, fragile discrete optics while the PA detector uses a MEMS microphone to replace bulky multi-pass cells.PA spectroscopy is among the most sensitive techniques available for monitoring chemical emissions or detecting gas traces. It relies on excitation of the chemical with a pulsed light source emitting at the absorption wavelengths of such molecules. The relaxation process creates local periodic variations of the temperature, resulting in stationary pressure waves, which high-performance microphones can detect.This new generation of devices, fully fabricated on silicon, shows performance comparable with state-of-the-art systems, with the huge bonus of small size and power efficiency that work well for mobile and wearable electronics. By supporting integration onto common technological platforms, such as on-chip photoacoustic sensors, researchers have successfully realized these miniaturized and cost-effective Mid-IR photonic devices in silicon. Mobile device and wearables manufacturers can now take advantage of manufacturable integrated devices for applications that are highly sensitive to size, performance and cost. Adding gas sensing to mobile devices and wearables is now very feasible.For more information on chemical sensing at CEA-Leti, please visit or contact: http://www.leti-cea.com/cea-tech/leti/englishCEA-Leti is an active member of SEMI-MEMS Sensors Industry Group. The technology research institute, along with Fraunhofer and imec, recently joined SEMI’s family as a Strategic Association Partner under a memorandum of understanding (MOU). Under this agreement, CEA-Leti will work with SEMI to advance technology roadmaps, industry standards and cutting-edge technologies including Internet of Things (IoT), artificial intelligence (AI) and machine learning that enable new capabilities across healthcare, automotive and other electronics manufacturing ecosystems. Sergio Nicoletti has more than 20 years of experience in micro and nanofabrication, including magnetic, superconducting and chemical sensing devices and technologies. Having joined CEA-Leti in 2006 as project manager for optical sensing devices used in chemical detection, Nicoletti is currently business development manager at the institute.Previous positions include research and project management at CNR-IMM (Bologna, Italy) and at Hitachi Global Storage Technologies. Nicoletti was also a visiting scientist at HGST (San Jose, Calif.), where he worked on magnetic recording-head devices.Nicoletti holds more than 20 patents and has more than 70 publications in peer-reviewed journals. In 2016, he was appointed coordinator of the European H2020 project MIRPHAB and is director of the project’s pilot line.Nicoletti received his Ph.D. in physics, with a focus on HTc superconducting devices, from Université Joseph Fourier (Grenoble, France). References“Photoacoustic cell on silicon for mid-infrared QCL-based spectroscopic analysis,” JG Coutard, A Glière, JM Fedeli, O Lartigue, J Skubich, G Aoust, A Teulle, T Strahl, S Nicoletti, M Carras, L Duraffourg. Proceedings Volume 10931, MOEMS and Miniaturized Systems XVIII; 109310V (2019) https://doi.org/10.1117/12.2506514“Miniaturization of mid-IR sensors on Si: challenges and perspectives,” S Nicoletti, JM Fédéli, M Fournier, P Labeye, P Barritault, A Marchant, A Glière, A Teulle, J Coutard, L Duraffourg - Silicon Proceedings Volume 10923, Silicon Photonics XIV; 109230H (2019) https://doi.org/10.1117/12.2506759

A short trip to Monterey, California provided an exciting glimpse into what is in store for the future. Along with 550 attendees and 60 exhibitors, I took a quick visit through the aisles and conference venue to find several exciting developments this year!So many exciting new products are on the horizon. Dr. Peter G. Hartwell, CTO of InvenSense, A TDK Group Company, provided a view future of the way sensors including optical, audio, balance, direction, location, and chemical will provide improvements over human capabilities. A glimpse into our future experiences with a 360-view winter wonderland experience of riding a snow mobile using two 180°C fisheye lens cameras with his presentation “Sensors: Where Reality Meets Virtual.” The only warning was that with so many cameras and social media privacy is lost!Dr. Hans Stork, CTO, ON Semiconductor discussed some of the recent investigations his company has made on the many LiDAR sensors. He enlightened listeners with more details of the optical/LiDAR Fusion with FUSE ONE that was unveiled at CES 2019. Future cars will have a combination of cameras, LiDAR, radar, and ultrasonics. No one sensor has it all. There are many companies offering LiDAR for automotive applications, but the products are still too expensive and the market will shake out over the next few years. Douglas Hackler, CEO, American Semiconductor presented the company’s achievement in flip chip on flex circuit assembly for a variety of applications, including pharmaceuticals, wearable wristbands, and IoT communications. Interconnects supported include ACA, ACF, advanced z-axis materials, and low temperature solder. He also described flexible hybrid electronics using printed electronics and a wafer CSP assembly for sensors. With this operation located in Idaho, products can be assembled in the U.S. Jean-Charles Souriau from CEA-Leti described the organization’s detailed research in developing in flip chip assembly on a flexible label with a thin die. A gold stud bump flip chip and thermo-compression bonding with glue is used to attach the die to a flex substrate. A polymer fabricated on thin glass was also demonstrated. Clearly, much progress has been made in flexible printed electronics in the last year with many presentations describing progress. Results of a benchmark study conducted at Cal Poly examined some of the key developments in bump materials and interconnect methods. Key areas such as antennas, batteries, PV and energy harvesting, a variety of sensors, and audio technology were investigated. Dr. Pradeep Lall presented work examining developments in conductive inks for 3D printed electronics.Dr. Subu Iyer and his student, Arsalan Alam, of UCLA presented some exciting research on heterogeneously integrated foldable display on elastomeric substrate, FlexTrate™, using vertically corrugated interconnects. This can be considered fan-out wafer level packaging. The work holds much promise for applications including foldable displays, wireless powered systems and surface electromyography systems. Fine pitch ≤40 micron interconnects bendable to 1 mm bending radius passed more than 6,000 bending cycles. Dr. Mark Poliks of Binghamton University described their work on the development of a wearable flexible hybrid electronics ECG monitor. While the work is in the early stages, human trials will soon begin and the results look promising. New materials will be key in the future products. Reliability test data was also presented on aerosol-jet printed traces on Upilex-S, including tensile, peel and bend testing, as well as “healing” of the damage. New product introductions included U.K’s Peratech’s EDGE force-sensing solution targeted form smartphones, wearables, and tablets. In this HMI solution, Peratech’s thin sensors are mechanically integrated into key areas of the smartphone to capture a user’s natural single-handed grip, ergonomic finger movements, intuitive pressure sand squeezes to control key functions. It even works with the users has wet hands or is wearing gloves! This eliminates the need for physical button openings and allows the implementation of a thinner, more contoured device with a rigid-metal chassis. Next year’s event will be in San Jose during the last week of February. Stay tuned to SEMI’s website for more details.Jan Vardaman is president and founder of TechSearch International, Inc., which has provided market research and technology trend analysis in semiconductor packaging since 1987. She is the co-author of How to Make IC Packages (by Nikkan Kogyo Shinbunsha), a columnist with Printed Circuit Design Fab/Circuits Assembly, and the author of numerous publications on emerging trends in semiconductor packaging and assembly. She is a senior member of IEEE EPS and is an IEEE EPS Distinguished Lecturer as well as a member of SEMI, SMTA, IMAPS, and MEPTEC.

Photo on left: My Skin Track pH by L'Oréal Group’s La Roche-Posay – the first wearable sensor and companion app to easily measure personal skin pH levels – leverages two decades of microfluidic and soft materials research in Professor John Rogers’ laboratory at the Center for Bio-Integrated Electronics and the Simpson Querrey Institute. As director of the Center for Bio-Integrated Electronics at Northwestern University, Professor John A. Rogers explores soft materials for conformal electronics, nanophotonic structures, microfluidic devices and MEMS, all with an emphasis on bio-inspired and bio-integrated technologies. During his keynote at FLEX and MEMS Sensors Technical Congress 2019, February 18-21 in Monterey, Calif., Rogers will present examples of the diverse, novel classes of biocompatible electronic and microfluidic systems with skin-like physical properties that stem from his work in materials science, mechanical engineering, electrical engineering and advanced manufacturing. SEMI’s Maria Vetrano caught up with Rogers to discuss his research, which has already been commercialized by companies such as L'Oréal Group.SEMI: What is the concept behind skin-interfaced electronic and microfluidic devices?ROGERS: Biological systems are mechanically soft, with complex, time-dependent 3D curvilinear shapes. Modern electronic and microfluidic technologies are rigid, with simple, static 2D layouts. We believe that eliminating this profound mismatch in physical properties will create vast opportunities in microsystems technologies (electronics, optoelectronics, microfluidics and microelectromechanical devices) that can intimately integrate with the human body for diagnostic, therapeutic or surgical functions. Skin-like devices that assess blood-glucose levels in real-time or continuously monitor the vital signs of infants in neonatal intensive care are just two examples of non-invasive, wirelessly connected biocompatible devices with the potential to dramatically improve quality of life.SEMI: What are some examples of commercially available biocompatible/microfluidic wearables that have leveraged your research?ROGERS: We’ve been fortunate in that we have been able to translate some of our ideas into commercial products for broad deployment in both life-enhancing and potentially life-saving applications. In sports and fitness, our skin-interfaced microfluidic systems form the basis of soft devices that capture, store and perform in-situ chemical analysis of sweat. These devices have been launched as products in two different categories – cosmetics and athletics – with two global brands. As an example of the former, L’Oréal Group just unveiled at CES 2019 My Skin Track pH, a thin, flexible version of this technology, designed to determine skin pH from measurement of sweat pH. Once armed with this information, L’Oréal customers can choose skincare products matched to their personal body chemistry. See the video on this device. Notably, a globally recognized consumer brand will reveal a product for athletics around the time of the 2019 Super Bowl on Sunday, February 3. A look inside My Skin Track pH, which uses Rogers Research Group technology from the Center for Bio-Integrated Electronics at Northwestern University Our technologies also have applications in clinical medicine and rehabilitation, including soft, skin-interfaced wireless sensors used to assess patient progress in stroke rehabilitation. In contrast with conventional, wired sensors that tether the patient to external boxes of electronics (a design that makes such devices impractical for in-home use), or conventional wearables that are confined to the wrist, our systems apply to the skin like a BAND-AID, and are described as “imperceptible” by stroke patients who are using them during rehab. These platforms measure speech, swallowing capability, movement of limbs, sleep quality, walking and balancing. Healthcare professionals can use the information collected to continue to monitor patients when they leave medical facilities, to understand how patients function in the real world. See video.SEMI: What work are you doing beyond flexible devices?ROGERS: We are pursuing devices that are unique not due to their soft mechanics, but due to their extremely small sizes. A good example is My Skin Track UV, which we recently commercialized with L’Oréal’s La Roche-Posay. This millimeter-scale, wireless, battery-free platform for digital UV dosimetry measures UV exposure dose continuously in real time and provides user access to this information via a smartphone app. My Skin Track UV is now available at all Apple stores across the U.S. and through the Apple website. See video. L’Oréal’s La Roche-Posay My Skin Track UVOther biocompatible/microfluidic devices based on our technology provide functionality that can save lives. Hydrocephalus patients suffer from a condition that, if unchecked, leads to excessive buildup of fluid in the brain. If left untreated, the resulting pressures can prove fatal.Hydrocephalus is treated with shunts, which drain accumulated fluid away from the intracranial space to a distal part of the body, often the abdomen. Unfortunately, however, shunts have a nearly 100 percent fail rate over a 10-year period, and testing them typically requires an MRI, CT scan or even surgery. Our technology serves as the basis of a bandage-sized, skin-like sensor that applies to the surface of the skin on the neck. Within five minutes of placement on the skin, the sensor can test non-invasively to determine if fluid is flowing through the shunt. The net result uniquely supports the rapid evaluation of shunts from home or other non-medical settings. The devices free patients from the constraints of hospitals, giving them a greater sense of security and independence. See video. SEMI: What would you like FLEX and MSTC attendees to take away from your presentation?ROGERS: I would like attendees to know that biocompatible microfluidic and electronic wearables that are flexible and conformal to the human body are no longer risky futuristic technologies that exist only in academic labs: They are emerging right now as key products in commercial markets for flexible hybrid electronics (FHE) and MEMS/sensors. Our group alone is anticipating deployment at the scale of tens to hundreds of millions of units in the markets in which we are seeing traction over the next five years. We believe that the broader area will become a multi-billion-dollar market opportunity in five to 10 years.John Rogers, Ph.D. will present Soft Electronic and Microfluidic Systems for the Skin at FLEX/MSTC on Tuesday, February 19 at 10:30 am.Register today to connect with him at the event. To learn more about Rogers Research Group, click here.MSTC Flex 2019 is organized by the MEMS Sensors Industry Group (MSIG) and FlexTech.Maria Vetrano is a public relations consultant at SEMI.