Scientists at Draper Laboratory, in Cambridge, are developing a biomedical nanosensor that could be injected into the skin, much like tattoo dye, to monitor an individual’s blood-sugar level. As the glucose level increases, the “tattoo” would fluoresce under an infrared light, telling a diabetic whether or not she needs an insulin shot following a meal. The researchers have already tested a sodium-sensing version of the device in mice, and will soon begin animal tests of the glucose-specific sensor.

Sodium and Blood Glucose Monitoring using Tattoo Biomedical NanoSensor and iPhone

Glucose Sensing Tattoo would appear Different in Color to Smartphone device if glucose levels are out of whack

The most reliable way to measure blood sugar is by pricking the finger for a tiny blood sample and using enzyme-laden test strips to detect glucose. In an attempt to free diabetics from this time-consuming and expensive regime, a number of novel glucose-sensing technologies are under development, from implanted devices that continually monitor blood sugar and dispense insulin, to noninvasive sensors that detect glucose through the skin via infrared light.

The biomedical sensor tattoo material consists of 120-nanometer polymer beads coated with a biocompatible material. Within each bead is a fluorescent dye and specialized sensor molecules, designed to detect specific chemicals, such as sodium or glucose.

Sodium and Blood Glucose Monitoring using iPhone/Smartphone

Using a biomedical nanosensor “tattoo” and a modified iPhone, cyclists could closely monitor sodium levels to prevent dehydration, and anemic patients could track their blood oxygen levels. A modified iPhone then tracks changes in the level of fluorescence, which indicates the amount of sodium or glucose present. The original reader was a large boxlike device. The researchers, Heather Clark and Matt Dubach, improved upon that by making a modified iPhone case that allows any iPhone to read the tattoos.

Here’s how it works: a case that slips over the iPhone contains a nine-volt battery, a filter that fits over the iPhone’s camera, and an array of three LEDs that produce light in the visible part of the spectrum. This light causes the tattoos to fluoresce. A light-filtering lens is then placed over the iPhone’s camera. This filters out the light released by the LEDs, but not the light emitted by the tattoo. The device is pressed to the skin to prevent outside light from interfering.