Highly sensitive passive radio frequency identification based sensor systems

Multifrequency impedance measurement technique for wireless characterization of microbiological cell cultures

An impedance measurement system with probe signal frequencies up to 50 kHz with AC-probe voltages below 30 mV rms was integrated for wireless and battery-free monitoring of microbiological cell cultures. The here presented modular design and the use of state-of-the-art components greatly eases adoptions to a wide range of biotechnological applications without the need of bulky LCR-meters or potentiostats. The device had a power consumption of less than 2.5 mA at a 3.3 V single power supply and worked trouble-free within the humid environment of a cell culture incubator. Measurements on lumped RC-elements showed an error of less than 1% for absolute values and less than 1° regarding the phase of the complex impedance. The performance of sensor devices with interdigitated electrode structures for the measurement of adherent cell cultures was tested in the presence of phosphate-buffered saline solution in the humid atmosphere of an incubator for biological cell cultures.

Wireless powered electronic sensors for biological applications

Radio frequency identification technology is used to power a novel platform of sensor devices. The employed energy harvesting system of the individual sensors enables a blanking of the radio frequency field for a defined period, while supplying the sensor electronics with a highly stable voltage. This guarantees interference free operation of the electronic circuitry during measurements. The implementation of this principle is demonstrated for a sensor system which is based on insets for state-of-the-art micro-titer-plates. Each inset is carrying electronic circuitry and an interdigitated electrode system which is acting as sensor for recording alterations of the cell metabolism. The presented sensor devices work without batteries and are designed for impedance measurements on microbiological cell cultures under physiological relevant conditions.