Researchers build liquid biopsy chip that detects metastatic cancer cells in blood: One blood sample can be tested for a comprehensive array of cancer cell markers.

A chip developed by mechanical engineers at Worcester Polytechnic Institute (WPI) can trap and identify metastatic cancer cells in a small amount of blood drawn from a cancer patient. The breakthrough technology uses a simple mechanical method that has been shown to be more effective in trapping cancer cells than the microfluidic approach employed in many existing devices.

The WPI device uses antibodies attached to an array of carbon nanotubes at the bottom of a tiny well. Cancer cells settle to the bottom of the well, where they selectively bind to the antibodies based on their surface markers (unlike other devices, the chip can also trap tiny structures called exosomes produced by cancers cells). This “liquid biopsy,” described in a recent issue of the journal Nanotechnology, could become the basis of a simple lab test that could quickly detect early signs of metastasis and help physicians select treatments targeted at the specific cancer cells identified.

Metastasis is the process by which a cancer can spread from one organ to other parts of the body, typically by entering the bloodstream. Different types of tumors show a preference for specific organs and tissues; circulating breast cancer cells, for example, are likely to take root in bones, lungs, and the brain. The prognosis for metastatic cancer (also called stage IV cancer) is generally poor, so a technique that could detect these circulating tumor cells before they have a chance to form new colonies of tumors at distant sites could greatly increase a patient’s survival odds.

A cross section of one of the wells in the WPI device, showing how cancer cells sink to the bottom of a blood sample, where they are captured by antibodies bound to carbon nanotubes. The bound cells trigger an electrical response, which is …more

“The focus on capturing circulating tumor cells is quite new,” said Balaji Panchapakesan, associate professor of mechanical engineering at WPI and director of the Small Systems Laboratory. “It is a very difficult challenge, not unlike looking for a needle in a haystack. There are billions of red blood cells, tens of thousands of white blood cells, and, perhaps, only a small number of tumor cells floating among them. We’ve shown how those cells can be captured with high precision.”

The device developed by Panchapakesan’s team includes an array of tiny elements, each about a tenth of an inch (3 millimeters) across. Each element has a well, at the bottom of which are antibodies attached to carbon nanotubes. Each well holds a specific antibody that will bind selectively to one type of cancer cell type, based on genetic markers on its surface. By seeding elements with an assortment of antibodies, the device could be set up to capture several different cancer cells types using a single blood sample. In the lab, the researchers were able to fill a total of 170 wells using just under 0.3 fluid ounces (0.85 milliliter) of blood. Even with that small sample, they captured between one and a thousand cells per device, with a capture efficiency of between 62 and 100 percent.

The carbon nanotubes used in the device act as semiconductors. When a cancer cell binds to one of the attached antibodies, it creates an electrical signature that can be detected. These signals can be used to identify which of the elements in the array have captured cancer cells. Those individual arrays can then be removed and taken to a lab, where the captured cells can be stained and identified under a microscope. In the lab, the binding and electrical signature generation process took just a few minutes, suggesting the possibility of getting same-day results from a blood test using the chip, Panchapakesan says.

In a paper published in the journal Nanotechnology, Panchapakesan’s team, which includes graduate students Farhad Khosravi, the paper’s lead author, and researchers at the University of Louisville and Thomas Jefferson University, describe a study in which antibodies specific for two markers of metastatic breast cancer, EpCam and Her2, were attached to the carbon nanotubes in the chip. When a blood sample that had been “spiked” with cells expressing those markers was placed on the chip, the device was shown to reliably capture only the marked cells.

In addition to capturing tumor cells, Panchapakesan says the chip will also latch on to tiny structures called exosomes, which are produced by cancers cells and carry the same markers. “These highly elusive 3-nanometer structures are too small to be captured with other types of liquid biopsy devices, such as microfluidics, due to shear forces that can potentially destroy them,” he noted. “Our chip is currently the only device that can potentially capture circulating tumor cells and exosomes directly on the chip, which should increase its ability to detect metastasis. This can be important because emerging evidence suggests that tiny proteins excreted with exosomes can drive reactions that may become major barriers to effective cancer drug delivery and treatment.”

Panchapakesan said the chip developed by his team has additional advantages over other liquid biopsy devices, most of which use microfluidics to capture cancer cells. In addition to being able to capture circulating tumor cells far more efficiently than microfluidic chips (in which cells must latch onto anchored antibodies as they pass by in a stream of moving liquid), the WPI device is also highly effective in separating cancer cells from the other cells and material in the blood through differential settling.

“White blood cells, in particular, are a problem, because they are quite numerous in blood and they can be mistaken for cancer cells,” he said. “Our device uses what is called a passive leukocyte depletion strategy. Because of density differences, the cancer cells tend to settle to the bottom of the wells (and this only happens in a narrow window), where they encounter the antibodies. The remainder of the blood contents stays at the top of the wells and can simply be washed away.”

While the initial tests with the chip have focused on breast cancer, Panchapakesan says the device could be set up to detect a wide range of tumor types, and plans are already in the works for development of an advanced device as well as testing for other cancer types, including lung and pancreas cancer. He says he envisions a day when a device like his could be employed not only for regular follow ups for patients who have had cancer, but in routine cancer screening.

“Imagine going to the doctor for your yearly physical,” he said. “You have blood drawn and that one blood sample can be tested for a comprehensive array of cancer cell markers. Cancers would be caught at their earliest stage and other stages of development, and doctors would have the necessary protein or genetic information from these captured cells to customize your treatment based on the specific markers for your cancer. This would really be a way to put your health in your own hands.”

Explore further: New device could improve cancer detection

More information: Farhad Khosravi et al. Static micro-array isolation, dynamic time series classification, capture and enumeration of spiked breast cancer cells in blood: the nanotube–CTC chip, Nanotechnology (2016). DOI: 10.1088/0957-4484/27/44/44LT03

Journal reference: Nanotechnology

Provided by: Worcester Polytechnic Institute

 

Tesla And Panasonic Finalize Solar Cell Production Agreement

Japanese electronics company Panasonic and U.S. electric car manufacture Tesla announced Tuesday that they have finalized an agreement, and will begin production of solar cells at a factory in Buffalo, New York.

In a statement released on Tuesday, the two companies said they plan to start production of photovoltaic (PV) cells and modules in the summer of 2017.

Panasonic will be investing more than $256 million in a New York production facility of Tesla Motors, and has agreed to pay capital costs for the manufacturing. In return, Tesla has made a “long-term purchase commitment” to Panasonic.

Tesla said this agreement will create 1,400 jobs in Buffalo, including 500 in manufacturing, and plans further expansion in Buffalo.

JB Straubel, Chief Technical Officer and Co-founder of Tesla, said “We are excited to expand our partnership with Panasonic as we move towards a combined Tesla and SolarCity.
By working together on solar, we will be able to accelerate production of high-efficiency, extremely reliable solar cells and modules at the best cost.”

The Associated Press reported:

SolarCity has committed to investing $5 billion over 10 years in New York state, hiring almost 1,500 workers at the Buffalo plant for five years and employing at least 2,000 more people across New York in exchange for use of the state-owned plant.

This plan is part of the solar partnership that the two companies first announced in October.

University of Central Florida: New ‘Super Nano-Wire Batteries’ that Charge in Seconds and Last for a Week!

Friday 9 December 2016

Leaving your phone plugged in for hours could become a thing of the past, thanks to a new type of battery technology that charges in seconds and lasts for over a week.

Scientists from the University of Central Florida (UCF) have created a supercapacitor battery prototype that can store a whole lot of energy very, very quickly.

While it probably won’t be commercially available for a years, the researchers said it has the potential to be used in phones, wearables and electric vehicles.

“If they were to replace the batteries with these supercapacitors, you could charge your mobile phone in a few seconds and you wouldn’t need to charge it again for over a week,” said Nitin Choudhary, a UCF postdoctoral associate, who conducted much of the research, published in the academic journal ACS Nano.
    Image: UCF

How does it work?

Unlike conventional batteries, supercapacitors store electricity statically on their surface which means they can charge and deliver energy rapidly. 

But supercapacitors have a major shortcoming: they need large surface areas in order to hold lots of energy.

To overcome the problem, the researchers developed supercapacitors built with millions of nano-wires and shells made from two-dimensional materials only a few atoms thick, which allows for super-fast charging. Their prototype is only about the size of a fingernail.

“For small electronic devices, our materials are surpassing the conventional ones worldwide in terms of energy density, power density and cyclic stability,” Choudhary said.

Cyclic stability refers to how many times a battery can be charged, drained and recharged before it starts to degrade. For lithium-ion batteries, this is typically fewer than 1,500 times. Supercapacitors with two-dimensional materials can be recharged a few thousand times. 

But the researchers say their prototype still works like new even after being recharged 30,000 times.

Those that use the new materials could be used in phones, tablets and other electronic devices, as well as electric vehicles. And because they’re flexible, it could mean a significant development for wearables.

Environmentally-friendly graphene textiles could enable wearable electronics

Credit: Jiesheng Ren

A new method for producing conductive cotton fabrics using graphene-based inks opens up new possibilities for flexible and wearable electronics, without the use of expensive and toxic processing steps.

Wearable, textiles-based electronics present new possibilities for flexible circuits, healthcare and environment monitoring, energy conversion, and many others. Now, researchers at the Cambridge Graphene Centre (CGC) at the University of Cambridge, working in collaboration with scientists at Jiangnan University, China, have devised a method for depositing graphene-based inks onto cotton to produce a conductive textile. The work, published in the journal Carbon, demonstrates a wearable motion sensor based on the conductive cotton.

Cotton fabric is among the most widespread for use in clothing and textiles, as it is breathable and comfortable to wear, as well as being durable to washing. These properties also make it an excellent choice for textile electronics. A new process, developed by Dr Felice Torrisi at the CGC, and his collaborators, is a low-cost, sustainable and environmentally-friendly method for making conductive cotton textiles by impregnating them with a graphene-based conductive ink.

Based on Dr Torrisi’s work on the formulation of printable graphene inks for flexible electronics, the team created inks of chemically modified graphene flakes that are more adhesive to cotton fibres than unmodified graphene. Heat treatment after depositing the ink on the fabric improves the conductivity of the modified graphene. The adhesion of the modified graphene to the cotton fibre is similar to the way cotton holds coloured dyes, and allows the fabric to remain conductive after several washes.

Although numerous researchers around the world have developed wearable sensors, most of the current wearable technologies rely on rigid electronic components mounted on flexible materials such as plastic films or textiles. These offer limited compatibility with the skin in many circumstances, are damaged when washed and are uncomfortable to wear because they are not breathable. 

“Other conductive inks are made from precious metals such as silver, which makes them very expensive to produce and not sustainable, whereas graphene is both cheap, environmentally-friendly, and chemically compatible with cotton,” explains Dr Torrisi.

 

Co-author Professor Chaoxia Wang of Jiangnan University adds: “This method will allow us to put electronic systems directly into clothes. It’s an incredible enabling technology for smart textiles.”

The work done by Dr Torrisi and Prof Wang, together with students Tian Carey and Jiesheng Ren, opens a number of commercial opportunities for graphene-based inks, ranging from personal health technology, high-performance sportswear, military garments, wearable technology/computing and fashion.

Electron microscopy image of a conductive graphene/cotton fabric. Credit: Jiesheng Ren

 

“Turning cotton fibres into functional electronic components can open to an entirely new set of applications from healthcare and wellbeing to the Internet of Things,” says Dr Torrisi “Thanks to nanotechnology, in the future our clothes could incorporate these textile-based electronics and become interactive.”

Graphene is carbon in the form of single-atom-thick membranes, and is highly conductive. The group’s work is based on the dispersion of tiny graphene sheets, each less than one nanometre thick, in a water-based dispersion. The individual graphene sheets in suspension are chemically modified to adhere well to the cotton fibres during printing and deposition on the fabric, leading to a thin and uniform conducting network of many graphene sheets. This network of nanometre flakes is the secret to the high sensitivity to strain induced by motion. A simple graphene-coated smart cotton textile used as a wearable strain sensor has been shown to reliably detect up to 500 motion cycles, even after more than 10 washing cycles in normal washing machine.

The use of graphene and other related 2D materials (GRMs) inks to create electronic components and devices integrated into fabrics and innovative textiles is at the centre of new technical advances in the smart textiles industry. Dr Torrisi and colleagues at the CGC are also involved in the Graphene Flagship, an EC-funded, pan-European project dedicated to bringing graphene and GRM technologies to commercial applications.

Graphene and GRMs are changing the science and technology landscape with attractive physical properties for electronics, photonics, sensing, catalysis and energy storage. Graphene’s atomic thickness and excellent electrical and mechanical properties give excellent advantages, allowing deposition of extremely thin, flexible and conductive films on surfaces and – with this new method – also on textiles. This combined with the environmental compatibility of graphene and its strong adhesion to cotton make the graphene-cotton strain sensor ideal for wearable applications.

The research was supported by grants from the European Research Council’s Synergy Grant, the International Research Fellowship of the National Natural Science Foundation of China and the Ministry of Science and Technology of China. The technology is being commercialised by Cambridge Enterprise, the University’s commercialisation arm.

Explore further: New study shows nickel graphene can be tuned for optimal fracture strength

More information: Jiesheng Ren et al. Environmentally-friendly conductive cotton fabric as flexible strain sensor based on hot press reduced graphene oxide, Carbon (2017). DOI: 10.1016/j.carbon.2016.10.045

Journal reference: Carbon

Provided by: University of Cambridge

 

In one-two punch, researchers load ‘nanocarriers’ to deliver cancer-fighting drugs and imaging molecules to tumors

Zhang’s group created this nanocarrier using a “load during assembly” approach, shown along the top. Images b, c and d are microscopic views of the nanocarriers at each major step of the assembly and loading process. Credit: Miqin Zhang

In one-two punch, researchers load ‘nanocarriers’ to deliver cancer-fighting drugs and imaging molecules to tumors

A conundrum of cancer is the tumor’s ability to use our bodies as human shields to deflect treatment. Tumors grow among normal tissues and organs, often giving doctors few options but to damage, poison or remove healthy parts of our body in attempts to beat back the cancer with surgery, chemotherapy or radiation.

But in a paper published Sept. 27 in the journal Small, scientists at the University of Washington describe a new system to encase chemotherapy drugs within tiny, synthetic “nanocarrier” packages, which could be injected into patients and disassembled at the tumor site to release their toxic cargo.

The group, led by UW professor of materials science and engineering Miqin Zhang, is not the first to work on nanocarriers. But the nanocarrier package developed by Zhang’s team is a hybrid of synthetic materials, which gives the nanocarrier the unique ability to ferry not just drugs, but also tiny fluorescent or magnetic particles to stain the tumor and make it visible to surgeons.

“Our nanocarrier system is really a hybrid addressing two needs — drug delivery and tumor imaging,” said Zhang, who is senior author on the paper. “First, this nanocarrier can deliver chemotherapy drugs and release them in the tumor area, which spares healthy tissue from toxic side effects. Second, we load the nanocarrier with materials to help doctors visualize the tumor, either using a microscope or by MRI scan.”

Their hybrid nanocarrier builds on years of research into the types of synthetic materials that could package drugs for delivery into a specific part of a patient’s body. In previous attempts, scientists would often first try make an empty nanocarrier out of a synthetic material. Once assembled, they would load the nanocarrier with a therapeutic drug. But this approach was inefficient, and carried a high risk of damaging the fragile drugs and rendering them ineffective.

“Most chemotherapy drugs have complex structures — essentially, they’re very fragile — and they do no good if they are broken by the time they reach the tumor,” said Zhang.

Zhang’s team worked around this problem by designing a nanocarrier that could be assembled and loaded simultaneously. Their approach is akin to laying cargo within a shipping container even as the container’s walls, floor and roof are being assembled and bolted together.

This “load during assembly” technique also let Zhang’s team incorporate multiple chemical components into the nanocarrier’s structure, which could help hold cargo in place and make the tumor easy to image in clinical settings.

Their nanocarrier sports a core of iron oxide, which provides structure but can also be used as an imaging agent in MRI scans. A shell of silica surrounds the core, and was designed to efficiently stack the chemotherapy drug paclitaxel. They also included space in the nanocarrier for carbon dots, tiny particles that can “stain” tissue and make it easier to see under a microscope, helping doctors resolve the boundaries between cancerous and healthy tissue for further treatment or surgery. The intensity of many imaging agents fades over time, but Zhang said this nanocarrier can provide sustained imaging for months.

Yet despite holding so much cargo, the fully loaded nanocarriers are less than the thickness of a sheet of flimsy notebook paper.

The silica shell keeps the nanocarriers watertight. In addition, they do not interfere with healthy tissue, as Zhang’s team showed by injecting healthy mice with empty nanocarriers or nanocarriers loaded with drug cargo. Five days after injection, they checked vital organs in the mice for evidence of toxicity and found none.

“This would indicate that the nanocarriers themselves do not trigger an adverse reaction in the body, and that the loaded nanocarriers are keeping their toxic cargo shielded from the body,” said Zhang.

The UW team also designed the nanocarriers to be easily disassembled once they reached a desired location. Gentle heating from low-level infrared light was sufficient to make the nanocarriers break apart and disgorge their cargo, which is something doctors could apply to the tumor site during treatment.

As their final test of the nanocarrier effectiveness, Zhang’s team turned to mice with a form of transmissible cancer. Mice that they injected with empty nanocarriers showed no reduction in tumor size. But tumors shrank significantly in mice injected with nanocarriers that were loaded with paclitaxel. They saw a similar affect on human cancer cells cultured and tested in the lab.

“These results show that the nanocarriers can deliver their cargo intact to the tumor site,” said Zhang. “And while we designed this nanocarrier specifically to accommodate paclitaxel, it is possible to adjust this technique for other drugs.”

There are still mountains to climb before this technology is proven safe and effective for humans. But Zhang hopes her team’s approach and promising results will accelerate the ascent.

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Story Source:

Materials provided by University of Washington. Original written by James Urton. Note: Content may be edited for style and length.

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Journal Reference:

1. Hui Wang, Kui Wang, Bowei Tian, Richard Revia, Qingxin Mu, Mike Jeon, Fei-Chien Chang, Miqin Zhang. Preloading of Hydrophobic Anticancer Drug into Multifunctional Nanocarrier for Multimodal Imaging, NIR-Responsive Drug Release, and Synergistic Therapy. Small, 2016; DOI: 10.1002/smll.201602263

Physics, photosynthesis and ‘Green’ solar cells

In a light harvesting quantum photocell, particles of light (photons) can efficiently generate electrons. When two absorbing channels are used, solar power entering the system through the two absorbers (a and b) efficiently generates power in the machine (M). Credit: Nathaniel Gabor and Tamar Melen

A University of California, Riverside assistant professor has combined photosynthesis and physics to make a key discovery that could help make solar cells more efficient. The findings were recently published in the journal Nano Letters.

Nathan Gabor is focused on experimental condensed matter physics, and uses light to probe the fundamental laws of quantum mechanics. But, he got interested in photosynthesis when a question popped into his head in 2010: Why are plants green? He soon discovered that no one really knows.

During the past six years, he sought to help change that by combining his background in physics with a deep dive into biology.

He set out to re-think solar energy conversion by asking the question: can we make materials for solar cells that more efficiently absorb the fluctuating amount of energy from the sun. Plants have evolved to do this, but current affordable solar cells — which are at best 20 percent efficient — do not control these sudden changes in solar power, Gabor said. That results in a lot of wasted energy and helps prevent wide-scale adoption of solar cells as an energy source.

Gabor, and several other UC Riverside physicists, addressed the problem by designing a new type of quantum heat engine photocell, which helps manipulate the flow of energy in solar cells. The design incorporates a heat engine photocell that absorbs photons from the sun and converts the photon energy into electricity.

Surprisingly, the researchers found that the quantum heat engine photocell could regulate solar power conversion without requiring active feedback or adaptive control mechanisms. In conventional photovoltaic technology, which is used on rooftops and solar farms today, fluctuations in solar power must be suppressed by voltage converters and feedback controllers, which dramatically reduce the overall efficiency.

The goal of the UC Riverside teams was to design the simplest photocell that matches the amount of solar power from the sun as close as possible to the average power demand and to suppress energy fluctuations to avoid the accumulation of excess energy.

The researchers compared the two simplest quantum mechanical photocell systems: one in which the photocell absorbed only a single color of light, and the other in which the photocell absorbed two colors. They found that by simply incorporating two photon-absorbing channels, rather than only one, the regulation of energy flow emerges naturally within the photocell.

The basic operating principle is that one channel absorbs at a wavelength for which the average input power is high, while the other absorbs at low power. The photocell switches between high and low power to convert varying levels of solar power into a steady-state output.

When Gabor’s team applied these simple models to the measured solar spectrum on Earth’s surface, they discovered that the absorption of green light, the most radiant portion of the solar power spectrum per unit wavelength, provides no regulatory benefit and should therefore be avoided. They systematically optimized the photocell parameters to reduce solar energy fluctuations, and found that the absorption spectrum looks nearly identical to the absorption spectrum observed in photosynthetic green plants.

The findings led the researchers to propose that natural regulation of energy they found in the quantum heat engine photocell may play a critical role in the photosynthesis in plants, perhaps explaining the predominance of green plants on Earth.

Other researchers have recently found that several molecular structures in plants, including chlorophyll a and b molecules, could be critical in preventing the accumulation of excess energy in plants, which could kill them. The UC Riverside researchers found that the molecular structure of the quantum heat engine photocell they studied is very similar to the structure of photosynthetic molecules that incorporate pairs of chlorophyll.

The hypothesis set out by Gabor and his team is the first to connect quantum mechanical structure to the greenness of plants, and provides a clear set of tests for researchers aiming to verify natural regulation. Equally important, their design allows regulation without active input, a process made possible by the photocell’s quantum mechanical structure.

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Story Source:

Materials provided by University of California – Riverside. Original written by Sean Nealon. Note: Content may be edited for style and length.

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Journal Reference:

1. Trevor B. Arp, Yafis Barlas, Vivek Aji, Nathaniel M. Gabor. Natural Regulation of Energy Flow in a Green Quantum Photocell. Nano Letters, 2016; DOI: 10.1021/acs.nanolett.6b03136

Nanotechnology in Smart Textiles and Wearables

The number and variety of smart textiles and wearable electronic devices has increased significantly in the past few years, as they offer significant enhancements to human comfort, health and well-being.

Wearable low-power silicon electronics, light-emitting diodes (LEDs) fabricated on fabrics, textiles with integrated Lithium-ion batteries (LIB) and electronic devices such as smart glasses, watches and lenses have been widely investigated and commercialized (e.g. Google glass, Apple Watch).

There is increasing demand for wearable electronics from industries such as:
– Medical and healthcare monitoring and diagnostics.

– Sportswear and fitness monitoring (bands).

– Consumer electronics such as smart watches, smart glasses and headsets.

– Military GPS trackers, equipment (helmets) and wearable robots.

– Smart apparel and footwear in fashion and sport.

– Workplace safety and manufacturing.

However, improvements in sensors, flexible & printable electronics and energy devices are necessary for wider implementation and nanomaterials and/or their hybrids are enabling the next phase convergence of textiles, electronics and informatics.

They  are opening the way for the integration of electronic components and sensors (e.g. heat and humidity) in high strength, flexible and electrically conductive textiles with energy storage and harvesting capabilities, biological functions, antimicrobial properties, and many other new functionalities.

The industry is now moving towards the development of electronic devices with flexible, thin, and large-area form factors.

Electronic devices that are fabricated on flexible substrates for application in flexible displays, electronic paper, smart packages, skin-like sensors, wearable electronics, implantable medical implements etc. is a fast growing market. Their future development depends greatly on the exploitation of advanced materials. (See Our YouTube Video – below)

Nanomaterials such as carbon nanotubes (CNT), silver nanowires graphene and other 2D materials are viewed as key materials for the future development of wearable electronics for implementation in healthcare and fitness monitoring, electronic devices incorporated into clothing and ‘smart skin’ applications (printed graphene-based sensors integrated with other 2D materials for physiological monitoring).

 

Genesis Nanotechnology Inc.

“Great Things from Small Things”

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Perovskite solar cells hit new world efficiency record

Dr. Anita Ho-Baillie, a Senior Research Fellow at the Australian Centre for Advanced Photovoltaics at UNSW, with the new perovskite cell. Credit: Rob Largent/UNSW

They’re flexible, cheap to produce and simple to make – which is why perovskites are the hottest new material in solar cell design. And now, engineers at Australia’s University of New South Wales in Sydney have smashed the trendy new compound’s world efficiency record.

Speaking at the Asia-Pacific Solar Research Conference in Canberra on Friday 2 December, Anita Ho-Baillie, a Senior Research Fellow at the Australian Centre for Advanced Photovoltaics (ACAP), announced that her team at UNSW has achieved the highest efficiency rating with the largest perovskite solar cells to date.

The 12.1% efficiency rating was for a 16 cm2 perovskite solar cell, the largest single perovskite photovoltaic cell certified with the highest energy conversion efficiency, and was independently confirmed by the international testing centre Newport Corp, in Bozeman, Montana.
The new cell is at least 10 times bigger than the current certified high-efficiency perovskite solar cells on record.

Her team has also achieved an 18% efficiency rating on a 1.2 cm2 single perovskite cell, and an 11.5% for a 16 cm2 four-cell perovskite mini-module, both independently certified by Newport.

“This is a very hot area of research, with many teams competing to advance photovoltaic design,” said Ho-Baillie. “Perovskites came out of nowhere in 2009, with an efficiency rating of 3.8%, and have since grown in leaps and bounds.

These results place UNSW amongst the best groups in the world producing state-of-the-art high-performance perovskite solar cells. And I think we can get to 24% within a year or so.”

Perovskite is a structured compound, where a hybrid organic-inorganic lead or tin halide-based material acts as the light-harvesting active layer. They are the fastest-advancing solar technology to date, and are attractive because the compound is cheap to produce and simple to manufacture, and can even be sprayed onto surfaces.

“The versatility of solution deposition of perovskite makes it possible to spray-coat, print or paint on solar cells,” said Ho-Baillie. “The diversity of chemical compositions also allows cells be transparent, or made of different colours. Imagine being able to cover every surface of buildings, devices and cars with solar cells.”

Most of the world’s commercial solar cells are made from a refined, highly purified silicon crystal and, like the most efficient commercial silicon cells (known as PERC cells and invented at UNSW), need to be baked above 800?C in multiple high-temperature steps.

Perovskites, on the other hand, are made at low temperatures and 200 times thinner than silicon cells.

But although perovskites hold much promise for cost-effective solar energy, they are currently prone to fluctuating temperatures and moisture, making them last only a few months without protection. Along with every other team in the world, Ho-Baillie’s is trying to extend its durability.

Thanks to what engineers learned from more than 40 years of work with layered silicon, they’re are confident they can extend this.

 

Nevertheless, there are many existing applications where even disposable low-cost, high-efficiency solar cells could be attractive, such as use in disaster response, device charging and lighting in electricity-poor regions of the world.
Perovskite solar cells also have the highest power to weight ratio amongst viable photovoltaic technologies.

“We will capitalise on the advantages of perovskites and continue to tackle issues important for commercialisation, like scaling to larger areas and improving cell durability,” said Martin Green, Director of the ACAP and Ho-Baillie’s mentor. The project’s goal is to lift perovskite solar cell efficiency to 26%.

The research is part of a collaboration backed by $3.6 million in funding through the Australian Renewable Energy Agency’s (ARENA) ‘solar excellence’ initiative. ARENA’s CEO Ivor Frischknecht said the achievement demonstrated the importance of supporting early stage renewable energy technologies:
“In the future, this world-leading R&D could deliver efficiency wins for households and businesses through rooftop solar as well as for big solar projects like those being advanced through ARENA’s investment in large-scale solar.”

To make a perovskite solar cells, engineers grow crystals into a structure known as ‘perovskite’, named after Lev Perovski, the Russian mineralogist who discovered it. They first dissolve a selection of compounds in a liquid to make the ‘ink’, then deposit this on a specialised glass which can conduct electricity. When the ink dries, it leaves behind a thin film that crystallises on top of the glass when mild heat is applied, resulting in a thin layer of perovskite crystals.

The tricky part is growing a thin film of perovskite crystals so the resulting solar cell absorbs a maximum amount of light.

Worldwide, engineers are working to create smooth and regular layers of perovskite with large crystal grain sizes in order to increase photovoltaic yields.

Ho-Baillie, who obtained her PhD at UNSW in 2004, is a former chief engineer for Solar Sailor, an Australian company which integrates solar cells into purpose-designed commercial marine ferries which currently ply waterways in Sydney, Shanghai and Hong Kong.