Novel sensor combining impedance spectroscopy and surface acoustic waves to detect blood coagulation time and hematocrit value

In this paper a new tool simultaneously to detect viscoelastic and dielectric properties of human fluids is presented. Therefore, one-port SAW resonators (SAW ... surface acoustic wave) with fundamental modes of 85, 170 und 340 MHz were developed. Shear horizontal polarized surface acoustic waves (SH-SAW) are used to detect the viscoelastic properties of coagulating blood and blood plasma samples. The electrode structure of these sensors additionally can be used simultaneously to detect the dielectric behavior of the whole system by impedance spectroscopy. Therefore, the sensor response in frequencies ranging from kHz to MHz is evaluated. The combination of both methods offers the detection of clinical relevant blood parameters like the blood coagulation time and the hematocrit value within one measurement. Such measurements can be carried out in less then 60 s. Realized as disposable sensors, these devices can be used both in point-of-care and in laboratory devices.