Smartphones are just about everywhere. In the U.S. alone, more than 91 million Americans now use a smartphone. Of course, these devices are much more than just a phone.

The fact that there are apps for many areas in personal health and medicine is a logical step to help individuals take better care of themselves and for researchers to find ways for individuals and physicians to do just that.

For example, researchers have been studying an app for epilepsy and stroke care. Other studies are looking at an app for testing kidney damage, and one for diagnosing cataracts.

A new app called Colorimetrix (in the video above) has shown promise as a portable diagnostic tool. Developed by researchers at the University of Cambridge, Colorimetrix could make monitoring of various medical conditions such as diabetes, kidney disease and urinary tract infections much clearer and easier for both patients and doctors. This app could also eventually be used to slow or limit the spread of pandemics in the developing world.

The way the app works is by taking a picture of the colorimetric test with the phone's camera. The app then compares the colors of the test with built-in parameters, calibrates the answer and displays the result, which can then be used for a diagnosis or sent to a healthcare professional. Researchers plan to release the app to the public, and they expect that this app could be applicable not only for human medicine, but for veterinary medicine and in laboratory applications.

Another smartphone app can help patients with alcohol use problems by supporting their recovery after a treatment program, with a way to reduce risky drinking days. The app called Addiction-Comprehensive Health Enhancement Support System (A-CHESS) includes relaxation techniques and sends alerts if patients are near a high-risk location, such as a bar they used to frequent. In a study of 170 patients who used the app, fewer risky drinking days were reported.

A start-up company called Qloudlab has developed a single-use film that is attached to the screen of a smartphone. The film is a plastic multilayer that works by analyzing blood that is absorbed into the film via capillary action. The phone can then run the blood test and interpret it. Those results are sent to a specific smartphone app, also created by Qloudlab. The results are then sent on to a doctor for assessment.

When it comes to maintaining health while traveling, anyone who has traveled across several time zones knows how difficult it is to adjust to those changes. The more time zones that are crossed, the more jet-lagged a traveler becomes. An app called Entrain, created by researchers at the University of Michigan, is slated to help overcome jet lag.

The user chooses the kind of light he or she expects to encounter during the trip. The app claims to be able to regulate the internal body clock through custom schedules of light and dark. Researchers say the app could not only help those who make long flights, but it may also help pilots, flight attendants and shift workers. This free app is already available for iPhones.

Even smartphone cases can monitor our health. A new health tracker called Wello is made up of a number of sensors that are embedded into the case of a smartphone. It can monitor vital signs, which are then sent to an app that can be downloaded onto the phone.

Clearly, the ongoing research, development and availability of health apps is on the forefront of medicine and shows no signs of slowing down.