US Army funded research may enhance battlefield medicine
07 May 2013
Imaging micro-organisms using visible or ultraviolet light without the requirement of any lenses, lasers or bulky optical elements.
Photograph (left) and schematic diagram (right) of the field-portable lens-free tomographic microscope, a device that will enable the 3D imaging of microscopic particles
Extramural basic research at the University of California, Los Angeles, funded by the US Army Research Laboratory's (ARL) Army Research Office, the Office of Naval Research and the US Defence Advanced Research Projects Agency, has led to the discovery of a fundamental new way to image micro-organisms using visible or ultraviolet light without the requirement of any lenses, lasers or bulky optical elements.
This new method, called holographic microscopy, may provide a cost-effective, handheld, lightweight and rapid diagnostic system to enhance battlefield medicine capabilities. Holographic microscopy can overcome many limitations of conventional optical microscopy.
Current optical microscopes are expensive, cumbersome to transport and require frequent technical maintenance. For example, accidentally jarring a microscope will typically require time-intensive realignment by a specialist.
In contrast, holographic microscopy simply requires a sensor, software, computing power and a display, and is enabling imaging devices that are inexpensive, compact and virtually maintenance-free.
This technology should allow imaging solutions at significantly lower cost (tens of dollars per device as opposed to thousands for each optical microscope), improved ruggedness (no moving parts or optics), reduced weight (grams rather than kilograms) and smaller size relative to optical microscopes.
Wallace Buchholz, the ARL programme manager for this research project, says that holographic microscopy can capture an image in less than a second and is capable of resolving bacteria and other microscopic objects over areas and depths-of-field thousands of times greater than possible with optical microscopes.
These capabilities are required attributes for three-dimensional imaging of microscopic particles, a powerful imaging capability that has never-before been available.
Given its compact, inexpensive and rugged characteristics, this new method may lead to new capabilities relevant to military clinicians. Tests that are currently restricted to hospitals or clinics could be readily conducted on the battlefield and in the remotest areas of the world.
For instance, blood, urine, fecal and tissue samples could be analysed for the presence of parasites and pathogens, and whole blood could be analysed for cell differentials to diagnose a variety of maladies such as discriminating between allergic reactions and infections.
Other potential applications of the technology might include detection of micro-fractures in material such as helicopter rotor blades, or detection of microbes on surfaces.
The research team have published results that demonstrate an adaptation of holography for use on cell phones, thereby providing a lightweight and highly-portable method for imaging fluids such as water, blood and urine to potentially detect and identify infectious diseases.
According to Dr Buchholz, this research has great promise for field use by the combatant; however, there are several key challenges remaining before practical field use of this technology can be realised.
Research efforts are underway to increase the resolution beyond 0.5 micrometer. Whereas this resolution is adequate for many needs, higher resolution will significantly increase versatility.
Furthermore, current and pending detection methods for pathogen identification must be adapted to the new platform, software that addresses specific military needs must be developed, and the technology must move quickly from the research and development stage to production and commercialisation.
Scientists in ARL's Sensors and Electron Devices Directorate are interested in using the technology as a 'miniature flow-through cytometer' for research in a size-limited anaerobic chamber, and in integrating this technology into future sensors and detectors.
Furthermore, proposals to a Chemical Biological Defence Small Business Innovation Research topic are currently under review for the potential development of a global disease surveillance network that would be used to monitor and track natural disease outbreaks.
The system could similarly monitor the release and spread of intentionally or accidentally released biological or chemical agents.