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Room temperature maser; a solid state result
NEWS
Prescribing sensitive cyborg tissues BIOMATERIALS
It is now possible to embed networks of biocompatible nanowire transistors within engineered tissues for better screening of new pharmaceuticals and ultimately for prosthetics and artificial organ transplants that have built-in diagnostic sensors and therapeutic technology. According to Charles Lieber of Harvard University and colleagues [Lieber et al., Nature Mater (2012) doi: 10.1038/nmat3404], one of the major challenges of developing next-generation prosthetics and synthetic organs composed of living tissue grown in the laboratory is incorporating sensors that can monitor the tissue and stimulate it or release therapeutics accordingly. Natural
tissues and organs have the autonomic nervous system to track pH, chemistry, oxygen levels and other factors. Tissue engineers would like to be able to emulate these intrinsic feedback loops so that fine control at the cellular and tissue level become possible for transplanted body parts and artificial tissues. The team has now used silicon wires that are just 80 nanometres in diameter to create mesh-like networks resembling “candy floss” (cotton-candy) within a threedimensional tissue culture. Previous researchers have been able to successfully engineer this kind of sensing network only in two-dimensional layouts. In such work, cells are cultured on the surface of electronic components or the sensors themselves are placed on tissue surfaces. Going 3D opens up a whole new realm of possibilities for developing realistic and responsive tissues. “In the short term, will be the development of this advance as a new platform for real-time in-vitro drug screening/testing from 3D tissue models (vs. traditional 2D cultured cells),” Lieber told Materials Today. “This is now an important goal in the pharmaceutical industry as it is now well-known that isolated cells or 2D arrays can behave very differently than cells in 3D tissue. New technology that allows access to screening throughout
3D tissue could greatly speed-up evaluations prior to animal or clinical trials,” he adds. “On a somewhat longer timescale, our advance could dramatically advance the power and sophistication of implanted prosthetic interfaces and/or tissue implants.” The team used heart and nerve cells and experimented with various biocompatible coatings to engineer nanoscale networks into the cell cultures without interfering with the normal growth and function of those cells. Then, using this network, the team was able to detect electrical signals generated by the cells, even those deep within the engineered tissue. They could also detect changes in those signals whencardio- or neurostimulating drugs were administered. The researchers were also able to construct bioengineered blood vessels with an embedded network for monitoring changes in pH inside or outside the vessel, a key step in creating artificial blood vessels that respond appropriately to inflammation or a fall in oxygen supply. “We have made a very simple proof of concept for this idea in our paper by ‘building’ a synthetic blood vessel innervated with nanoelectronic circuitry to sense the pH inside and outside the blood vessel,” Lieber adds.
David Bradley
Room temperature maser; a solid state result ELECTRONIC MATERIALS Researchers from the National Physical Laboratory (NPL) and Imperial College London have developed a solid-state maser that works at ambient temperature. Microwave Amplification by Stimulated Emission of Radiation pre-dates its light-based counterpart, the laser, but has always suffered a major drawback in terms of applications: masers only work at the chilly depths of temperatures close to absolute zero or at very low pressures.Moreover, they also need to sit in a strong magnetic field in order to generate their coherent microwave beams. A room temperature device that works without magnets has now been described by the UK team [Oxborrow, M., et al., Nature 488, 353-356; doi: 10.1038/nature11339]. This demonstration might now make masers practically and economically viable for a wide range of applications. For instance, a room-temperature maser could be developed for medical imaging, remote chemical sensors and perhaps for more sensitive radio telescopes that could even be used to search for extraterrestrial life.
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NPL team member Mark Oxborrow explains that, “For half a century the maser has been the forgotten, inconvenient cousin of the laser,” he says. “Our design breakthrough will enable masers to be used by industry and consumers.” Rather than using the rubies of lowtemperature masers, the team has turned to a different kind of crystal, an organic p-terphenyl compound doped with pentacene, By an intriguing quirk of chemistry this crystal is also bright red although it is entirely unrelated to the chromium-contaminated aluminium oxide of a ruby. In the current demonstration, the maser operates only in pulsed mode with each burst of coherent microwaves lasting for a fraction of a second, and moreover only available in a narrow frequency range. The team is currently investigating other materials to find alternatives that can be used in a continuous-mode maser and at other microwave frequencies. They are also figuring out how to improve the portability of their maser. “Getting the device to work continuously is a stiff
OCTOBER 2012 | VOLUME 15 | NUMBER 10
The maser core. Image courtesy of NPL. challenge that we are now working on,” Oxborrow told Materials Today. Today, lasers are ubiquitous in our everyday lives as the read-write device in optical media like CDs and DVDs, for holographic technology and optical communications as well as in surgical and industrial cutting. Now that the maser has come out of the cold, the pressure is on to see whether it could become as ubiquitous a technology as the laser.
David Bradley
Prescribing sensitive cyborg tissues BIOMATERIALS
It is now possible to embed networks of biocompatible nanowire transistors within engineered tissues for better screening of new pharmaceuticals and ultimately for prosthetics and artificial organ transplants that have built-in diagnostic sensors and therapeutic technology. According to Charles Lieber of Harvard University and colleagues [Lieber et al., Nature Mater (2012) doi: 10.1038/nmat3404], one of the major challenges of developing next-generation prosthetics and synthetic organs composed of living tissue grown in the laboratory is incorporating sensors that can monitor the tissue and stimulate it or release therapeutics accordingly. Natural
tissues and organs have the autonomic nervous system to track pH, chemistry, oxygen levels and other factors. Tissue engineers would like to be able to emulate these intrinsic feedback loops so that fine control at the cellular and tissue level become possible for transplanted body parts and artificial tissues. The team has now used silicon wires that are just 80 nanometres in diameter to create mesh-like networks resembling “candy floss” (cotton-candy) within a threedimensional tissue culture. Previous researchers have been able to successfully engineer this kind of sensing network only in two-dimensional layouts. In such work, cells are cultured on the surface of electronic components or the sensors themselves are placed on tissue surfaces. Going 3D opens up a whole new realm of possibilities for developing realistic and responsive tissues. “In the short term, will be the development of this advance as a new platform for real-time in-vitro drug screening/testing from 3D tissue models (vs. traditional 2D cultured cells),” Lieber told Materials Today. “This is now an important goal in the pharmaceutical industry as it is now well-known that isolated cells or 2D arrays can behave very differently than cells in 3D tissue. New technology that allows access to screening throughout
3D tissue could greatly speed-up evaluations prior to animal or clinical trials,” he adds. “On a somewhat longer timescale, our advance could dramatically advance the power and sophistication of implanted prosthetic interfaces and/or tissue implants.” The team used heart and nerve cells and experimented with various biocompatible coatings to engineer nanoscale networks into the cell cultures without interfering with the normal growth and function of those cells. Then, using this network, the team was able to detect electrical signals generated by the cells, even those deep within the engineered tissue. They could also detect changes in those signals whencardio- or neurostimulating drugs were administered. The researchers were also able to construct bioengineered blood vessels with an embedded network for monitoring changes in pH inside or outside the vessel, a key step in creating artificial blood vessels that respond appropriately to inflammation or a fall in oxygen supply. “We have made a very simple proof of concept for this idea in our paper by ‘building’ a synthetic blood vessel innervated with nanoelectronic circuitry to sense the pH inside and outside the blood vessel,” Lieber adds.
David Bradley
Room temperature maser; a solid state result ELECTRONIC MATERIALS Researchers from the National Physical Laboratory (NPL) and Imperial College London have developed a solid-state maser that works at ambient temperature. Microwave Amplification by Stimulated Emission of Radiation pre-dates its light-based counterpart, the laser, but has always suffered a major drawback in terms of applications: masers only work at the chilly depths of temperatures close to absolute zero or at very low pressures.Moreover, they also need to sit in a strong magnetic field in order to generate their coherent microwave beams. A room temperature device that works without magnets has now been described by the UK team [Oxborrow, M., et al., Nature 488, 353-356; doi: 10.1038/nature11339]. This demonstration might now make masers practically and economically viable for a wide range of applications. For instance, a room-temperature maser could be developed for medical imaging, remote chemical sensors and perhaps for more sensitive radio telescopes that could even be used to search for extraterrestrial life.
424
NPL team member Mark Oxborrow explains that, “For half a century the maser has been the forgotten, inconvenient cousin of the laser,” he says. “Our design breakthrough will enable masers to be used by industry and consumers.” Rather than using the rubies of lowtemperature masers, the team has turned to a different kind of crystal, an organic p-terphenyl compound doped with pentacene, By an intriguing quirk of chemistry this crystal is also bright red although it is entirely unrelated to the chromium-contaminated aluminium oxide of a ruby. In the current demonstration, the maser operates only in pulsed mode with each burst of coherent microwaves lasting for a fraction of a second, and moreover only available in a narrow frequency range. The team is currently investigating other materials to find alternatives that can be used in a continuous-mode maser and at other microwave frequencies. They are also figuring out how to improve the portability of their maser. “Getting the device to work continuously is a stiff
OCTOBER 2012 | VOLUME 15 | NUMBER 10
The maser core. Image courtesy of NPL. challenge that we are now working on,” Oxborrow told Materials Today. Today, lasers are ubiquitous in our everyday lives as the read-write device in optical media like CDs and DVDs, for holographic technology and optical communications as well as in surgical and industrial cutting. Now that the maser has come out of the cold, the pressure is on to see whether it could become as ubiquitous a technology as the laser.
David Bradley