Grip strength, as well as walking speed and gait length, can be indicators of a person's physical and mental health. A variety of conditions and treatments can be monitored from the grip strength, but such measurements are typically only performed infrequently at the doctor's office. IBM Research has just developed a sensor that is attached to a fingernail on the index finger, that can measure the finger's motion and from that figure out the grip strength. The engineers were originally motivated to create a device that can help with monitoring of Parkinson's patients, as changes in a medication regimen should normally be accounted by changes in symptoms. Since most Parkinson's sufferers are older folks, skin-based sensors can be not as accurate and may lead to unwanted infections, but the fingernail is safer in this respect and provide a great deal of information about a person's daily activities.