430 results about "Impedance spectrum" patented technology

An impedance spectroscopy system for monitoring ischemic mucosal damage in hollow viscous organs comprises a sensor catheter and an impedance spectrometer for electrically driving the catheter to obtain a complex tissue impedance spectrum. Once the catheter is in place in one of a patient's hollow viscous organs, the impedance spectrometer obtains the complex impedance spectrum by causing two electrodes in the tip of the catheter to inject a current into the mucosal tissue at different frequencies, while two other electrodes measure the resulting voltages. A pattern recognition system is then used to analyze the complex impedance spectrum and to quantify the severity of the mucosal injury. Alternatively, the complex impedance spectrum can be appropriately plotted against the spectrum of normal tissue, allowing for a visual comparison by trained personnel.

Methods and systems for calibration of RFID sensors used in manufacturing and monitoring systems are provided. The methods include measuring impedance of an RFID sensor antenna, relating the measurement of impedance to one or more parameters (such as physical, chemical and biological properties), computing one or more analytical fit coefficients, and storing the one or more analytical fit coefficients on a memory chip of the RFID sensor. Measuring impedance of the RFID sensor may comprise measuring complex impedance which involves measuring complex impedance spectrum, phase angle and magnitude of the impedance, at least one of frequency of the maximum of the real part of the complex impedance, magnitude of the real part of the complex impedance, zero-reactance frequency, resonant frequency of the imaginary part of the complex impedance, and antiresonant frequency of the imaginary part of the complex impedance. Also provided are manufacturing or monitoring systems comprised of an RFID sensor wherein the RFID sensor comprises, a memory chip, an antenna, and a sensing film wherein analytical fit coefficients are stored on the memory chip to allow calibration of the RFID sensor. Also provided are manufacturing or monitoring systems comprised of an RFID sensor wherein the RFID sensor comprises, a memory chip, an antenna, and a complementary sensor attached to the antenna where the complementary sensor in a pre-calibrated fashion predictably affects the impedance of the antenna.