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Invention of the first integrated circularly polarized light detector on a silicon chip opens the door for development of small, portable sensors that could expand the use of polarized light for drug screening, surveillance, optical communications and quantum computing, among other potential applications.

The new detector was developed by a team of Vanderbilt University engineers directed by Assistant Professor of Mechanical Engineering Jason Valentine working with researchers at Ohio University. The work is described in an article published on Sept. 22 in the online journal Nature Communications.

Wei Li, left, and Jason Valentine in the lab. (Anne Rayner / Vanderbilt)

Wei Li, left, and Jason Valentine in the lab. (Anne Rayner / Vanderbilt)

“Although it is largely invisible to human vision, the polarization state of light can provide a lot of valuable information,” said Valentine. “However, the traditional way of detecting it requires several optical elements that are quite bulky and difficult to miniaturize. We have managed to get around this limitation by the use of ‘metamaterials’ — materials engineered to have properties that are not found in nature.”

Polarized light comes in two basic forms: linear and circular. In a ray of unpolarized light, the electrical fields of individual photons are oriented in random directions. In linearly polarized light the fields of all the photons lie in the same plane. In circularly polarized light (CPL), the fields lie in a plane that continuously rotates through 360 degrees. As a result there are two types of circularly polarized light, right-handed and left-handed.

Humans cannot readily distinguish the polarization state of light, but there are a number of other species that possess “p-vision.” These include cuttlefish, mantis shrimp, bees, ants and crickets.

Cuttlefish also produce varying patterns of polarized light on their skin, which has led scientists to hypothesize that they use this as a secret communication channel that neither their predators or prey can detect. This has led to the suggestion that CPL could be used to increase the security of optical communications by including polarized channels that would be invisible to those who don’t have the proper detectors.

Unlike unpolarized light, CPL can detect the difference between right-handed and left-handed versions of molecules. Just like hands and gloves, most biological molecules come in mirror-image pairs. This property is called chirality. For example, cells contain only left-handed amino acids but they metabolize only right-handed sugars (a fact utilized by some artificial sweeteners which use left-hand forms of sugar which taste just as sweet as the right-hand version but which the body cannot convert into fat).

Illustration of how circularly polarized light passes through the silicon chip and is absorbed by the metamaterial. (Valentine Lab / Vanderbilt)

Illustration of how circularly polarized light passes through the silicon chip and is absorbed by the metamaterial. (Valentine Lab / Vanderbilt)

Chirality can be dramatically important in drugs because their biological activity is often related to their handedness. For example, one form of dopamine is effective in the management of Parkinson’s disease while the other form reduces the number of white blood cells. One form of thalidomide alleviates morning sickness while the other causes birth defects. The number of chiral drugs in use today is estimated to be 2,500 and most new drugs under development are chiral.

“Inexpensive CPL detectors could be integrated into the drug production process to provide real time sensing of drugs,” said Vanderbilt University doctoral student Wei Li, who played a key role in designing and testing the device. “Portable detectors could be used to determine drug chirality in hospitals and in the field.”

The metamaterial that the researchers developed to detect polarized light consists of silver nanowires laid down in a sub-microscopic zig-zag pattern on an extremely thin sheet of acrylic fixed to an optically thick silver plate. This metamaterial is attached to the bottom of a silicon wafer with the nanowire side up.

The nanowires generate a cloud of free-flowing electrons that produce “plasmon” density waves that efficiently absorb energy from photons that pass through the silicon wafer. The absorption process creates “hot” or energetic electrons that shoot up into the wafer where they generate a detectable electrical current.

The zig-zag pattern can be made either right-handed or left-handed. When it is right-handed, the surface absorbs right circularly polarized light and reflects left circularly polarized light. When it is left-handed it absorbs left circularly polarized light and reflects right circularly polarized light. By including both right-handed and left-handed surface patterns, the sensor can differentiate between right and left circularly polarized light.

Three images of the same surface demonstrate the new detector's capability. The researchers coated the surface with right- and -left-handed metamaterial in the form of the Vanderbilt logo. The image on the left was taken in plain polarized light. The one in the center was taken with left-handed circularly polarized light. And the image on the right was taken with right-handed circularly polarized light. (Valentine Lab / Vanderbilt)

Three images of the same surface demonstrate the new detector’s capability. The researchers coated the surface with right- and -left-handed metamaterial in the form of the Vanderbilt logo. The image on the left was taken in plain polarized light. The one in the center was taken with left-handed circularly polarized light. And the image on the right was taken with right-handed circularly polarized light. (Valentine Lab / Vanderbilt)

There have been two previous efforts to make solid-state polarized light detectors. According to Li, one used chiral organic materials that are unstable in air, worked only in a narrow range of wavelengths and had a limited power range. Another was based on a more complicated multilayer design that only worked at low temperatures.

“That is the beauty of metamaterials: You can design them to work in the fashion you desire,” said Li.

The efficiency of their prototype is 0.2 percent — too low to be commercially viable. Now that they have proven the viability of their approach, however, they have a number of ideas for how they can boost the efficiency to a level comparable to conventional photodetectors.

The research was supported by National Science Foundation grant CBET-1336455, Office of Naval Research grant N00014-14-1-0475, U.S. Army Research Office grant W911NF-12-1-0407 and the Volkswagen Foundation.

 

Novati Technologies Inc., a global nanotechnology development center, today announced the availability of the industry’s most advanced Integrated Sensor Platform, placing a wide variety of sensors onto multi-layer stacks of wafers in order to consume less power and perform significantly faster while reducing overall footprint. Already proven for customer devices at Novati’s commercial development and manufacturing center, the platform paves the way for stacking single or multiple sensors with a broad selection of popular–as well as emerging–substrate materials, enabling new high-end applications for markets that include medical, semiconductors, photonics, security, and aerospace.

Demonstrating a version of this capability for high-performance computing, Novati last month jointly announced with Tezzaron Semiconductor the industry’s first eight-layer 3D IC wafer stack containing active logic, which controls the memory layers. The transistor and interconnect densities per cubic millimeter were far higher than achievable with 2D 14nm silicon fabrication, representing the densest 3D IC ever reported. Not limited to the high-end markets served by that achievement, Novati’s Integrated Sensor Platform also offers great promise as an enabler for the Internet of Things (IoT).

“Energy harvesting is one of the important capabilities needed for the broad set of markets that aim to utilize the integration of sensing and processing,” said Tony Massimini, Chief of Technology for Semico Research. “Novati’s platform offers technology for integrating this energy harvesting ecosystem that includes energy generator, converters, power management, MCUs, energy storage and connectivity for small, wireless autonomous devices, like those used in wearable electronics and wireless sensor networks.”

For the past three years, Novati has demonstrated wafer-to-wafer integration of up to eight wafers, as well as custom sensors integrated directly onto mainstream CMOS architectures. With 3D manufacturing options available on both 200mm and 300mm lines, Novati offers circuit designers an unprecedented degree of freedom to architect the smart sensors of the future.

“While the ability to create multi-chip devices has been around for decades, Novati’s innovative sensor platform can accelerate the Internet of Things by expanding the ways for devices to connect and interact with all types of environments,” said David Anderson, President and CEO of Novati. “Using this platform, the world can integrate novel sensor functionality to virtually any circuitry, including digital logic, analog, mixed signal and memory–and stacking multiple sensors will soon follow. This opens a new, unlimited landscape for designers to significantly improve functionality while reducing costs and time to market.”

As an example of Novati’s substrate integration, their nanomanufacturing site bonded Tezzaron’s wafers directly, wafer-to-wafer, producing devices that can be thinned and finished to the same thickness as conventional 2D dies. The result was excellent electrical, thermal and mechanical performance. Novati’s capability to integrate sensors with such a stacked platform already has led to novel, proprietary product development for several customers.

Building on its ability to provide the world’s most advanced Integrated Sensor Platform and other innovations for the microelectronics markets, Novati intends to open its next office in Europe, where site selection is underway. In order to jointly plan new devices using novel materials that enable micro- and nanoscale functions and analyses, the company will be meeting with companies from around the globe during its participation at SEMICON Europa electronics conference in Dresden for the week of October 6.

“Europe has always been an important market for us and we are excited to continue expansion in this area,” said Julian Searle, Director of Account Management for Novati. “As the innovation initiatives in Europe continue to progress, Novati’s commercialization services and solutions are often the first call for technical pioneers that need to transform great ideas into great products.”

To the growing list of two-dimensional semiconductors, such as graphene, boron nitride, and molybdenum disulfide, whose unique electronic properties make them potential successors to silicon in future devices, you can now add hybrid organic-inorganic perovskites. However, unlike the other contenders, which are covalent semiconductors, these 2D hybrid perovskites are ionic materials, which gives them special properties of their own.

Researchers at the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) have successfully grown atomically thin 2D sheets of organic-inorganic hybrid perovskites from solution. The ultrathin sheets are of high quality, large in area, and square-shaped. They also exhibited efficient photoluminescence, color-tunability, and a unique structural relaxation not found in covalent semiconductor sheets.

“We believe this is the first example of 2D atomically thin nanostructures made from ionic materials,” says Peidong Yang, a chemist with Berkeley Lab’s Materials Sciences Division and world authority on nanostructures, who first came up with the idea for this research some 20 years ago. “The results of our study open up opportunities for fundamental research on the synthesis and characterization of atomically thin 2D hybrid perovskites and introduces a new family of 2D solution-processed semiconductors for nanoscale optoelectronic devices, such as field effect transistors and photodetectors.”

Yang, who also holds appointments with the University of California (UC) Berkeley and is a co-director of the Kavli Energy NanoScience Institute (Kavli-ENSI), is the corresponding author of a paper describing this research in the journal Science. The paper is titled “Atomically thin two-dimensional organic-inorganic hybrid perovskites.” The lead authors are Letian Dou, Andrew Wong and Yi Yu, all members of Yang’s research group. Other authors are Minliang Lai, Nikolay Kornienko, Samuel Eaton, Anthony Fu, Connor Bischak, Jie Ma, Tina Ding, Naomi Ginsberg, Lin-Wang Wang and Paul Alivisatos.

Traditional perovskites are typically metal-oxide materials that display a wide range of fascinating electromagnetic properties, including ferroelectricity and piezoelectricity, superconductivity and colossal magnetoresistance. In the past couple of years, organic-inorganic hybrid perovskites have been solution-processed into thin films or bulk crystals for photovoltaic devices that have reached a 20 percent power conversion efficiency. Separating these hybrid materials into individual, free-standing 2D sheets through such techniques as spin-coating, chemical vapor deposition, and mechanical exfoliation has met with limited success.

In 1994, while a PhD student at Harvard University, Yang proposed a method for preparing 2D hybrid perovskite nanostructures and tuning their electronic properties but never acted upon it. This past year, while preparing to move his office, he came upon the proposal and passed it on to co-lead author Dou, a post-doctoral student in his research group. Dou, working mainly with the other lead authors Wong and Yu, used Yang’s proposal to synthesize free-standing 2D sheets of CH3NH3PbI3, a hybrid perovskite made from a blend of lead, bromine, nitrogen, carbon and hydrogen atoms.

“Unlike exfoliation and chemical vapor deposition methods, which normally produce relatively thick perovskite plates, we were able to grow uniform square-shaped 2D crystals on a flat substrate with high yield and excellent reproducibility,” says Dou. “We characterized the structure and composition of individual 2D crystals using a variety of techniques and found they have a slightly shifted band-edge emission that could be attributed to structural relaxation. A preliminary photoluminescence study indicates a band-edge emission at 453 nanometers, which is red-shifted slightly as compared to bulk crystals. This suggests that color-tuning could be achieved in these 2D hybrid perovskites by changing sheet thickness as well as composition via the synthesis of related materials.”

The well-defined geometry of these square-shaped 2D crystals is the mark of high quality crystallinity, and their large size should facilitate their integration into future devices.

“With our technique, vertical and lateral heterostructures can also be achieved,” Yang says. “This opens up new possibilities for the design of materials/devices on an atomic/molecular scale with distinctive new properties.”

The research was supported by DOE’s Office of Science. The characterization work was carried out at the Molecular Foundry’s National Center for Electron Microscopy, and at beamline 7.3.3 of the Advanced Light Source. The Molecular Foundry and the Advanced Light Source are DOE Office of Science User Facilities hosted at Berkeley Lab.

Rectennas in Baratunde A. Cola's NEST (NanoEngineered Systems and Transport) lab

Rectennas in Baratunde A. Cola’s NEST (NanoEngineered Systems and Transport) lab

Using nanometer-scale components, researchers have demonstrated the first optical rectenna, a device that combines the functions of an antenna and a rectifier diode to convert light directly into DC current.

Based on multiwall carbon nanotubes and tiny rectifiers fabricated onto them, the optical rectennas could provide a new technology for photodetectors that would operate without the need for cooling, energy harvesters that would convert waste heat to electricity–and ultimately for a new way to efficiently capture solar energy.

In the new devices, developed by engineers at the Georgia Institute of Technology, the carbon nanotubes act as antennas to capture light from the sun or other sources. As the waves of light hit the nanotube antennas, they create an oscillating charge that moves through rectifier devices attached to them. The rectifiers switch on and off at record high petahertz speeds, creating a small direct current.

Billions of rectennas in an array can produce significant current, though the efficiency of the devices demonstrated so far remains below one percent. The researchers hope to boost that output through optimization techniques, and believe that a rectenna with commercial potential may be available within a year.

“We could ultimately make solar cells that are twice as efficient at a cost that is ten times lower, and that is to me an opportunity to change the world in a very big way” said Baratunde Cola, an associate professor in the George W. Woodruff School of Mechanical Engineering at Georgia Tech. “As a robust, high-temperature detector, these rectennas could be a completely disruptive technology if we can get to one percent efficiency. If we can get to higher efficiencies, we could apply it to energy conversion technologies and solar energy capture.”

The research, supported by the Defense Advanced Research Projects Agency (DARPA), the Space and Naval Warfare (SPAWAR) Systems Center and the Army Research Office (ARO), is reported September 28 in the journal Nature Nanotechnology.

Developed in the 1960s and 1970s, rectennas have operated at wavelengths as short as ten microns, but for more than 40 years researchers have been attempting to make devices at optical wavelengths. There were many challenges: making the antennas small enough to couple optical wavelengths, and fabricating a matching rectifier diode small enough and able to operate fast enough to capture the electromagnetic wave oscillations. But the potential of high efficiency and low cost kept scientists working on the technology.

“The physics and the scientific concepts have been out there,” said Cola. “Now was the perfect time to try some new things and make a device work, thanks to advances in fabrication technology.”

Using metallic multiwall carbon nanotubes and nanoscale fabrication techniques, Cola and collaborators Asha Sharma, Virendra Singh and Thomas Bougher constructed devices that utilize the wave nature of light rather than its particle nature. They also used a long series of tests–and more than a thousand devices–to verify measurements of both current and voltage to confirm the existence of rectenna functions that had been predicted theoretically. The devices operated at a range of temperatures from 5 to 77 degrees Celsius.

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Fabricating the rectennas begins with growing forests of vertically-aligned carbon nanotubes on a conductive substrate. Using atomic layer chemical vapor deposition, the nanotubes are coated with an aluminum oxide material to insulate them. Finally, physical vapor deposition is used to deposit optically-transparent thin layers of calcium then aluminum metals atop the nanotube forest. The difference of work functions between the nanotubes and the calcium provides a potential of about two electron volts, enough to drive electrons out of the carbon nanotube antennas when they are excited by light.

In operation, oscillating waves of light pass through the transparent calcium-aluminum electrode and interact with the nanotubes. The metal-insulator-metal junctions at the nanotube tips serve as rectifiers switching on and off at femtosecond intervals, allowing electrons generated by the antenna to flow one way into the top electrode. Ultra-low capacitance, on the order of a few attofarads, enables the 10-nanometer diameter diode to operate at these exceptional frequencies.

“A rectenna is basically an antenna coupled to a diode, but when you move into the optical spectrum, that usually means a nanoscale antenna coupled to a metal-insulator-metal diode,” Cola explained. “The closer you can get the antenna to the diode, the more efficient it is. So the ideal structure uses the antenna as one of the metals in the diode–which is the structure we made.”

The rectennas fabricated by Cola’s group are grown on rigid substrates, but the goal is to grow them on a foil or other material that would produce flexible solar cells or photodetectors.

Cola sees the rectennas built so far as simple proof of principle. He has ideas for how to improve the efficiency by changing the materials, opening the carbon nanotubes to allow multiple conduction channels, and reducing resistance in the structures.

“We think we can reduce the resistance by several orders of magnitude just by improving the fabrication of our device structures,” he said. “Based on what others have done and what the theory is showing us, I believe that these devices could get to greater than 40 percent efficiency.”

Notes:

This work was supported by the Defense Advanced Research Projects Agency (DARPA), the Space and Naval Warfare (SPAWAR) Systems Center, Pacific under YFA grant N66001-09-1-2091, and by the Army Research Office (ARO), through the Young Investigator Program (YIP), under agreement W911NF-13-1-0491. The statements in this release are those of the authors and do not necessarily reflect the official views of DARPA, SPAWAR or ARO. Georgia Tech has filed international patent applications related to this work under PCT/US2013/065918 in the United States (U.S.S.N. 14/434,118), Europe (No. 13847632.0), Japan (No. 2015-538110) and China (No. 201380060639.2)

CITATION: Asha Sharma, Virendra Singh, Thomas L. Bougher and Baratunde A. Cola, “A carbon nanotube optical rectenna,” (Nature Nanotechnology, 2015). http://dx.doi.org/10.1038/nnano.2015.220

Researchers from Holst Centre (set up by TNO and imec), imec and CMST, imec’s associated lab at Ghent University, have demonstrated the world’s first stretchable and conformable thin-film transistor (TFT) driven LED display laminated into textiles. This paves the way to wearable displays in clothing providing users with feedback.

Wearable devices such as healthcare monitors and activity trackers are now a part of everyday life for many people. Today’s wearables are separate devices that users must remember to wear. The next step forward will be to integrate these devices into our clothing. Doing so will make wearable devices less obtrusive and more comfortable, encouraging people to use them more regularly and, hence, increasing the quality of data collected. A key step towards realizing wearable devices in clothing is creating displays that can be integrated into textiles to allow interaction with the wearer.

“Wearable devices allow people to monitor their fitness and health so they can live full and active lives for longer. But to maximize the benefits wearables can offer, they need to be able to provide feedback on what users are doing as well as measuring it. By combining imec’s patented stretch technology with our expertise in active-matrix backplanes and integrating electronics into fabrics, we’ve taken a giant step towards that possibility,” says Edsger Smits, Senior research scientist at Holst Centre.

The conformable display is very thin and mechanically stretchable. A fine-grain version of the proven meander interconnect technology was developed by the CMST lab at Ghent University and Holst Centre to link standard (rigid) LEDs into a flexible and stretchable display. The LED displays are fabricated on a polyimide substrate and encapsulated in rubber, allowing the displays to be laminated in to textiles that can be washed. Importantly, the technology uses fabrication steps that are known to the manufacturing industry, enabling rapid industrialization.

Following an initial demonstration at the Society for Information Display’s Display Week in San Jose, USA earlier this year, Holst Centre has presented the next generation of the display at the International Meeting on Information Display (IMID) in Daegu, Korea, 18-21 August 2015. Smaller LEDs are now mounted on an amorphous indium-gallium-zinc oxide (a-IGZO) TFT backplane that employs a two-transistor and one capacitor (2T-1C) pixel engine to drive the LEDs. These second-generation displays offer higher pitch and increased, average brightness. The presentation will feature a 32×32 pixel demonstrator with a resolution of 13 pixels per inch (ppi) and average brightness above 200 candelas per square meter (cd/m2). Work is ongoing to further industrialize this technology.

The world’s first stretchable and conformable thin-film transistor (TFT) driven LED display laminated into textiles developed by Holst Centre, imec and CSMT.

The world’s first stretchable and conformable thin-film transistor (TFT) driven LED display laminated into textiles developed by Holst Centre, imec and CSMT.

The pure-play foundry market is forecast to grow to an all-time high of $12.2 billion in 4Q15, following several quarters in which sales remained between $11.3 and $11.8 billion, based on IC Insights’ updated foundry forecast presented in the August Update to The McClean Report 2015 (Figure 1). IC Insights defines a pure-play foundry as a company that does not offer a significant amount of IC products of its own design, but instead focuses on producing ICs for other companies (e.g., TSMC, GlobalFoundries, UMC, SMIC, etc.).

Fig 1

Fig 1

The quarterly pure-play IC foundry market has recently displayed a seasonal pattern in which the best growth rate takes place in the second quarter of the year and a sales downturn occurs in the fourth quarter.  Given that about 98 percent of pure-play foundries’ sales are to IDMs and fabless companies that will re-sell the devices they purchase from the foundry, it makes sense that the pure-play foundries’ strongest seasonal quarter (second quarter) is one quarter earlier than the total IC industry’s strongest seasonal quarter (third quarter).

However, as shown in the figure, 2015 is not expected to display the typical pure-play foundry quarterly revenue pattern.  Although 1Q15 registered its usual weakness, 2Q15 showed a sequential decline, rather than an increase. In 2012, 2013, and 2014, second quarter pure-play foundry revenue showed strong double-digit growth.  In 2Q15, results were decidedly atypical with a 2 percent decline in pure-play foundry sales. The primary reason behind the 2Q15 sales decline was the 5 percent 2Q15/1Q15 revenue decline by foundry giant TSMC.  TSMC’s 5 percent sequential decline was equivalent to a $366 million drop in its revenue.

For 4Q15, IC Insights forecasts that the quarterly pure-play foundry market will show a higher than normal growth rate of 4 percent.  With most of the inventory adjustments that held back growth in the first half of the year expected to be completed by the end of 3Q15, 4Q15 is forecast to register enough growth to boost the quarterly pure-play foundry market to over $12.0 billion for the first time.

Nanoengineers at the University of California, San Diego used an innovative 3D printing technology they developed to manufacture multipurpose fish-shaped microrobots — called microfish — that swim around efficiently in liquids, are chemically powered by hydrogen peroxide and magnetically controlled. These proof-of-concept synthetic microfish will inspire a new generation of “smart” microrobots that have diverse capabilities such as detoxification, sensing and directed drug delivery, researchers said.

3-D-printed microfish contain functional nanoparticles that enable them to be self-propelled, chemically powered and magnetically steered. The microfish are also capable of removing and sensing toxins. Credit: J. Warner, UC San Diego Jacobs School of Engineering.

3-D-printed microfish contain functional nanoparticles that enable them to be self-propelled, chemically powered and magnetically steered. The microfish are also capable of removing and sensing toxins. Credit: J. Warner, UC San Diego Jacobs School of Engineering.

The technique used to fabricate the microfish provides numerous improvements over other methods traditionally employed to create microrobots with various locomotion mechanisms, such as microjet engines, microdrillers and microrockets. Most of these microrobots are incapable of performing more sophisticated tasks because they feature simple designs — such as spherical or cylindrical structures — and are made of homogeneous inorganic materials. In this new study, researchers demonstrated a simple way to create more complex microrobots.

The research, led by Professors Shaochen Chen and Joseph Wang of the NanoEngineering Department at the UC San Diego, was published in the Aug. 12 issue of the journal Advanced Materials.

By combining Chen’s 3D printing technology with Wang’s expertise in microrobots, the team was able to custom-build microfish that can do more than simply swim around when placed in a solution containing hydrogen peroxide. Nanoengineers were able to easily add functional nanoparticles into certain parts of the microfish bodies. They installed platinum nanoparticles in the tails, which react with hydrogen peroxide to propel the microfish forward, and magnetic iron oxide nanoparticles in the heads, which allowed them to be steered with magnets.

“We have developed an entirely new method to engineer nature-inspired microscopic swimmers that have complex geometric structures and are smaller than the width of a human hair. With this method, we can easily integrate different functions inside these tiny robotic swimmers for a broad spectrum of applications,” said the co-first author Wei Zhu, a nanoengineering Ph.D. student in Chen’s research group at the Jacobs School of Engineering at UC San Diego.

As a proof-of-concept demonstration, the researchers incorporated toxin-neutralizing nanoparticles throughout the bodies of the microfish. Specifically, the researchers mixed in polydiacetylene (PDA) nanoparticles, which capture harmful pore-forming toxins such as the ones found in bee venom. The researchers noted that the powerful swimming of the microfish in solution greatly enhanced their ability to clean up toxins. When the PDA nanoparticles bind with toxin molecules, they become fluorescent and emit red-colored light. The team was able to monitor the detoxification ability of the microfish by the intensity of their red glow.

“The neat thing about this experiment is that it shows how the microfish can doubly serve as detoxification systems and as toxin sensors,” said Zhu.

“Another exciting possibility we could explore is to encapsulate medicines inside the microfish and use them for directed drug delivery,” said Jinxing Li, the other co-first author of the study and a nanoengineering Ph.D. student in Wang’s research group.

How this new 3D printing technology works

The new microfish fabrication method is based on a rapid, high-resolution 3D printing technology called microscale continuous optical printing (μCOP), which was developed in Chen’s lab. Some of the benefits of the μCOP technology are speed, scalability, precision and flexibility. Within seconds, the researchers can print an array containing hundreds of microfish, each measuring 120 microns long and 30 microns thick. This process also does not require the use of harsh chemicals. Because the μCOP technology is digitized, the researchers could easily experiment with different designs for their microfish, including shark and manta ray shapes.

“With our 3D printing technology, we are not limited to just fish shapes. We can rapidly build microrobots inspired by other biological organisms such as birds,” said Zhu.

The key component of the μCOP technology is a digital micromirror array device (DMD) chip, which contains approximately two million micromirrors. Each micromirror is individually controlled to project UV light in the desired pattern (in this case, a fish shape) onto a photosensitive material, which solidifies upon exposure to UV light. The microfish are built using a photosensitive material and are constructed one layer at a time, allowing each set of functional nanoparticles to be “printed” into specific parts of the fish bodies.

“This method has made it easier for us to test different designs for these microrobots and to test different nanoparticles to insert new functional elements into these tiny structures. It’s my personal hope to further this research to eventually develop surgical microrobots that operate safer and with more precision,” said Li.

North America-based manufacturers of semiconductor equipment posted $1.59 billion in orders worldwide in July 2015 (three-month average basis) and a book-to-bill ratio of 1.02, according to the July EMDS Book-to-Bill Report published today by SEMI.  A book-to-bill of 1.02 means that $102 worth of orders were received for every $100 of product billed for the month.

SEMI reports that the three-month average of worldwide bookings in July 2015 was $1.59 billion. The bookings figure is 5.1 percent higher than the final June 2015 level of $1.52 billion, and is 12.5 percent higher than the July 2014 order level of $1.42 billion.

The three-month average of worldwide billings in July 2015 was $1.56 billion. The billings figure is 0.3 percent higher than the final June 2015 level of $1.55 billion, and is 18.2 percent higher than the July 2014 billings level of $1.32 billion.

“Year-to-date, the bookings and billings reported in the SEMI North American equipment book-to-bill report indicate a solid year for the industry,” said SEMI president and CEO Denny McGuirk. “The outlook for the remainder of the year is somewhat clouded, but we see investments in 3D NAND and advanced packaging as drivers.”

The SEMI book-to-bill is a ratio of three-month moving averages of worldwide bookings and billings for North American-based semiconductor equipment manufacturers. Billings and bookings figures are in millions of U.S. dollars.

Billings
(3-mo. avg)

Bookings
(3-mo. avg)

Book-to-Bill
February 2015 

$1,280.1

$1,313.7

1.03
March 2015 

$1,265.6

$1,392.7

1.10
April 2015 

$1,515.3

$1,573.7

1.04
May 2015 

$1,557.3

$1,546.2

0.99
June 2015 (final)

$1,554.9

$1,517.4

0.98
July 2015 (prelim)

$1,559.3

$1,594.3

1.02

Source: SEMI (www.semi.org), August 2015

The global market for semiconductors used in smart meters that provide two-way communications between meters and utilities will continue to expand in the coming years, providing significant growth opportunities semiconductor manufacturers. Shipments of communicating meters are forecast to reach 132 million units in 2015 and 150 million units in 2019, according to IHS Inc. (NYSE: IHS), a global source of critical information and insight.

Global revenues for semiconductors used in water, gas and electric meters reached $1.2 billion in 2014, with a year-over-year growth of 11 percent and a five-year compound annual growth rate of 8 percent. The average semiconductor cost in two-way meters was approximately $11 in 2014. Average selling prices (ASPs) are expected to increase over time, as industry needs increase for 32-bit micro-controller units (MCUs), memory chips, single system-on-chip (SoC) solutions and other components used in secured communications and other applications.

Based on the latest information from the IHS Industrial Semiconductor Market Tracker, the demand for precise energy measurement and communication has increased the penetration of micro-component integrated circuits (ICs), along with analog ICs. In fact, two thirds of meter semiconductor revenue comes from microcontroller and analog components.

“The semiconductor industry for electric meters is moving toward a single-chip solution for measuring and communicating with the grid station, which is an important industry trend to watch,” said Robbie Galoso, associate director, semiconductor market shares and industrial electronics for IHS Technology. “Water and gas meters require fewer semiconductor components; however, they need extra semiconductors for sensing and battery management.”

Meters installed in the latter half of this decade will require greater application complexity, better security, improved communication ability, enhanced remote control ability and higher resolution. That means increased need for memory and system-on-chip (SoC) solutions with greater capabilities in a smaller package than in the past.

Meters are evolving from those that merely register end-user usage, into complicated machines that can be queried for on-demand data, upgraded remotely, shut off in case of emergency or non-payment and used for variable pricing. “The movement from 8-bit MCUs to higher margin 32-bit MCUs is a key industry trend,” said Noman Akhtar, analyst for IHS Technology. “The integration of these higher function microcontroller units also requires additional capabilities, such as increased memory, which further increases manufacturing costs.”

Smart_Semis_Chart

Global consumers have lately become less interested in acquiring conventional notebooks with 15-inch displays, and they are instead shifting their spending to smaller product segments. In the first half of 2015, panel shipments in the 15-inch range (i.e., 15.0 inches to 15.9 inches) dropped 14 percent year over year, from 44.5 million to 38.4 million units, according to IHS Inc. (NYSE: IHS), a global source of critical information and insight. At the same time, driven by the popularity of Chromebook, notebook display shipments in the 11-inch range have grown from 8 million units to 11 million units.

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“Thanks to affordable prices, and a completed ecosystem with a host of hardware and app choices and a user-friendly cloud environment, Chromebook has expanded its customer base from small and medium-sized businesses and the education market to general users,” said Jason Hsu, supply chain senior analyst for IHS Technology. “The Chromebook sales region has also expanded from the United States to emerging countries, where more local brands are launching Chromebook product offerings. There are also more products set to debut in the 12-inch range, thanks to the success of the Microsoft Surface Pro 3 and rumors of Apple’s upcoming 12.9-inch tablets.”

According to the most recent IHS Notebook and Tablet Display Supply Chain Tracker, total notebook panel shipments to Lenovo and Hewlett-Packard fell 27 percent month over month from 6.4 million units in May to 4.7 million units in June, while overall set production increased by 13 percent from 5.4 million units to 6.1 million units. These two leading notebook PC brands have recently taken steps to regulate panel inventory, in order to guard against excess product pre-stocking.

“The currency depreciation in Euro zone and emerging counties earlier this year jeopardized consumer confidence and slowed the purchase of consumer electronics, including notebooks,” Hsu said. “Moreover, in April, Microsoft leaked the announcement of its new Windows 10 operating system. Despite Microsoft’s claims that a free upgrade to the new operating system would be available to Windows 8 users, many consumers still deferred purchases, which increased the brands’ set inventory. Notebook manufacturers could decide to lower set production in the third quarter, after the end market becomes sluggish in May and June.”

With notebook panel prices remaining very low, profitability has become an issue, and many panel makers are facing pressure to maintain fab loading and gain market share. “Panel cost structure has become crucial in the struggle to stay competitive,” Hsu said. “Continuous panel over-supply not only hurts profitability, but could also confuse the real panel market demand in the fourth quarter of 2015 and the first quarter of 2016. It’s time for panel makers to revise their production numbers, and curb capacity utilization, to keep pace with actual market demand.”