Inductive distance sensor for biomedical applications

Our novel inductive distance measurement system use 3 excitation and 3 sensing coils. The system was developed for monitoring the activity of the human stomach, but the miniature sensors allow to use it on rats. Multiple coil system allows corrections for the angular misalignment and lateral displacement. Inductive principle was shown to be more precise than traditionally ultrasound distance meters, which are affected by variations of sound velocity in different tissues and body liquids. Also the power consumption of our system is low enough for implantable devices. The achieved sensitivity is 4.7 muV in 10 mm distance between the transmitter and sensor capsules, each of them being 1 mm in diameter and 4 mm in length; the resolution is 20 mum.