Micro and nanosized sensors can make use of a wide range of technologies that most effectively detect a targeted chemical or physical property. Researchers at Texas A&M and Penn State use polyethylene glycol beads coated with fluorescent molecules to monitor diabetes blood sugar levels. The beads are injected under the skin and stay in the interstitial fluid. When glucose in the interstitial fluid drops to dangerous levels, glucose displaces the fluorescent molecules and creates a glow. This glow is seen on a tattoo
placed on the arm.

Another approach by researchers at the University of Michigan is using dendrimers attached with fluorescent tags to sense pre-malignant and cancerous changes inside livingcells. The dendrimers are administered transdermally and because of their small size, passthrough membranes into white blood cells to detect early signs of biochemical changesfrom radiation or infection. Radiation changes the flow of calcium ions within the white blood cells and eventually triggers apoptosis, or programmed cell death (PCD) due to the radiation or infection. The fluorescent tags attached to the dendrimers will glow in the presence of the death cells when passed with a rentinal scanning device using a laser capable of detecting the fluorescence. A similar application is being researched with
NASA for detecting radiation levels in astronauts.

Sensor microchips are also being developed to continuously monitor key body parameters including pulse, temperature and blood glucose. A chip would be implanted under the skin and transmit a signal that could be monitored continuously.

Another application uses optical microsensors implanted into subdermal or deep tissue to monitor tissue circulation after surgery. Instrumentation is linked to transmit data to a nearby sensor to provide very early indication of inadequate circulation if the surgery is unsuccessful. Another type of implantable sensor uses MEMS devices and accelerometers for monitoring and treating paralysed limbs. Implantable MEMS sensors can measure strain, acceleration, angular rate and related parameters to determine normal and problem data.