The quality of smartphone cameras has increased exponentially over the past decade. Today's smartphone cameras can not only capture photos that rival those of stand-alone camera systems but also offer practical applications, like heart-rate measurement, foreign-text translation, and augmented reality.
What's the next major functionality of smartphone cameras? It could be the ability to identify chemicals, drugs, and biological molecules, according to a new study published in the Review of Scientific Instruments.
The study describes how a team of scientists at Texas A&M turned a common smartphone into a "pocket-sized" Raman and emission spectral detector by modifying it with just $50 worth of extra equipment. With the added hardware, the smartphone was able to identify chemicals in the field within minutes.
The technology could have a wide range of applications, including diagnosing certain diseases, detecting the presence of pathogens and dangerous chemicals, identifying impurities in food, and verifying the authenticity of valuable artwork and minerals.
Raman and fluorescence spectroscopy
Raman and fluorescence spectroscopies are techniques for discerning the chemical composition of materials. Both strategies exploit the fact that light interacts with certain types of matter in unique ways. But there are some differences between the two techniques.
As the name suggests, fluorescence spectroscopy measures the fluorescence — that is, the light emitted by a substance when it absorbs light or other electromagnetic radiation — of a given material. It works by shining light on a material, which excites the electrons within the molecules of the material. The electrons then emit fluorescent light toward a filter that measures fluorescence.
The particular spectra of fluorescent light that's emitted can help scientists detect small concentrations of particular types of biological molecules within a material. But some biomolecules, such as RNA and DNA, don't emit fluorescent light, or they only do so at extremely low levels. That's where Raman spectroscopy comes into play.
Raman spectroscopy involves shooting a laser at a sample and observing how the light scatters. When light hits molecules, the atoms within the molecules vibrate and photons get scattered. Most of the scattered light is of the same wavelength and color as the original light, so it provides no information. But a tiny fraction of the light gets scattered differently; that is, the wavelength and color are different. Known as Raman scattering, this is extremely useful because it provides highly precise information about the chemical composition of the molecule. In other words, all molecules have a unique Raman "fingerprint."
Creating an affordable, pocket-sized spectrometer
To build the spectrometer, the researchers connected a smartphone to a laser and a series of plastic lenses. The smartphone camera was placed facing a transmission diffraction grating, which splits incoming light into its constituent wavelengths and colors. After a laser is fired into a sample, the scattered light is diffracted through this grating, and the smartphone camera analyzes the light on the other side.
Schematic diagram of the designed system.Credit: Dhankhar et al.
To test the spectrometer, the researchers analyzed a range of sample materials, including carrots and bacteria. The laser used in the spectrometer emits a wavelength that's readily absorbed by the pigments in carrots and bacteria, which is why these materials were chosen.
The results showed that the smartphone spectrometer was able to correctly identify the materials, but it wasn't quite as effective as the best commercially available Raman spectrometers. The researchers noted that their system might be improved by using specific High Dynamic Range (HDR) smartphone camera applications.
Ultimately, the study highlights how improving the fundamentals of a technology, like smartphone cameras, can lead to a surprisingly wide range of useful applications.
"This inexpensive yet accurate recording pocket Raman system has the potential of being an integral part of ubiquitous cell phones that will make it possible to identify chemical impurities and pathogens, in situ within minutes," the researchers concluded.
For every great evolutionary innovation, there is a new way for things to go wrong.
Multicellularity allowed for more complex organisms, but those organisms became susceptible to cancer. The evolution of asymmetric cell division was a boon that prevented damaged cells from proliferating but also created the mechanisms which cause us to age. Blood cell traits that help prevent malaria can also cause sickle cell anemia. Improvements in our brain power can lead to mental illnesses that no other animal can get. In short, it seems that our own genetics can be both a blessing and a curse.
While this is interesting in and of itself, a team of researchers led by Dr. Mary Benton of Baylor University recently published an essay in Nature Reviews Genetics on the influence of evolutionary history on human health and disease and possible new approaches to treating ailments caused by our own genetics. Their essay considers how evolution accidentally made us susceptible to certain diseases and how genomics might be used to improve health outcomes.
No good idea goes unpunished
Credit: Benton et al.
As the above chart shows, evolutionary advances that impact our health occurred at various points in history. As the environment, both natural and social, changes, traits and adaptations that worked really well in the past can become a source of problems. Consider, for example, the tendency of humans to want sweet foods that were once rare. This was likely a useful trait to have when it evolved, but the surplus of sweets we have these days has resulted in an obesity epidemic. Outside of its original context, a once adaptive trait can become maladaptive.
Understanding the context within which certain traits entered the human genome can shed light on why they are now causing problems. This can yield further insights on population genetics and even personalized medicine. As the authors put it:
"Much like a family's medical history over generations, the genome is fundamentally a historical record. Decoding the evolution of the human genome provides valuable context for interpreting and modeling disease."
"While most of the variations that impact disease risk evolved recently, they are part of more complex systems that go much further back. With our improving understanding of how these variations interact with our modern environment, society, and cultures, doctors can potentially begin to use a patient's genetic history to help craft personal care plans."
An evolutionary understanding of disease
While evolutionary takes on disease are not currently used for most conditions, the capacity for medical professionals to do so is increasing. The authors mention the potential of polygenic risk scores, a recently developed technology that estimates the effect of a subject's genetics on their health, as a possible application of evolutionary history on individual health.
While not everyone can get a full genome record at this moment, the possibilities of using our evolutionary history in medicine are tremendous. Dr. Benton spoke to these possibilities with the Baylor University News Service:
"If we can better understand our genomes, then we can better understand risk for disease broadly, but also for specific people. Understanding how genetic variants relate to disease can help us tailor treatments, preventative measures, or drugs. Evolution plays into what variants we have, which variants have stuck around, which people they are present in, and why. I think evolution gives us context for what we want to use in the clinic moving forward."
