Piezoelectric layer embedded-microdiaphragm sensors for the determination of blood viscosity and density

Abstract

We introduce a lead zirconate titanate [PZT; Pb(Zr0.52Ti0.48)O3] microdiaphragm resonating sensor packaged in a polydimethylsiloxane chip. The proposed sensor can measure the density and viscosity of a liquid that is within the density and viscosity regime of blood (1.060 × 103 kg/m3, 3–4 cP). To verify the basic characteristics of the sensor, viscous solutions were prepared from glycerol and deionized water with a density in the range from 0.998 to 1.263 × 103 kg/m3 and a viscosity in the range from 1 to 1414 cP. We measured the frequency responses of the sensor before and after injecting the viscosity- and density-controlled liquid under the bottom of the microdiaphragm. The resonant frequencies in the (1,1) and (2,2) modes decreased linearly as a function of the liquid density in the range from 0.998 to 1.146 × 103 kg/m3 with a sensitivity of 28.03 Hz/kg·m−3 and 81.85 Hz/kg·m−3, respectively. The full width at half maximum had a logarithmic relationship with the liquid viscosity in the viscosity range from 1 to 8.4 cP. The quality factor (Q-factor) for the 50% glycerol/water mixture was determined to be greater than 20 for both the (1,1) and the (2,2) modes, indicating that the microdiaphragm resonating sensor is suitable for measuring the density and viscosity of a liquid within a density range from 0.998 to 1.1466 × 103 kg/m3 and a viscosity range from 1 to 8.4 cP. These density and viscosity ranges span the regime of possible changes of blood characteristics. The microdiaphragm resonating sensors were also tested with a real human serum to verify that the sensor is suitable for measuring the viscosity and density of blood. Therefore, the PZT microdiaphragm resonating sensor could be utilized for early diagnosis of diseases associated with changes in the physical properties of blood.

Precision density and viscosity measurement using two cantilevers with different widths

“…The PLL-based frequency tracking enables fast and accurate detection which makes the system more practical compared to frequency sweep based methods using network analysers. An important point to highlight is the achieved accuracies for viscosity and density are well suited for blood and blood plasma measurements [13,19]. Within the scope of this study we focused on proving the capability of the method to extract density and viscosity and did not force to achieve higher accuracy in a broader dynamic range.…”

“…A general approach to separate viscosity and density effects experimentally is to relate quality factor changes with viscosity and resonant peak shifts with density [6][7][8][9]. This approach is also used with other types of MEMS structures like Suspended microchannel resonators (SMR) [11,12] and piezoelectric MEMS resonators [13][14][15][16] and suspended microcapillary resonators [17]. With this approach in order to attain high sensitivity in a broad dynamic range, frequency sweeps with high frequency resolution is necessary.…”

Enhancing the Responsivity of Uncooled Infrared Detectors Using Plasmonics for High-Performance Infrared Spectroscopy

“…In conclusion, a gold plasmonic crystal structure is designed, optimized by numerical simulations and fabricated on top of our PZT sensor [26] to demonstrate a strategy to enhance the responsivity of IR detectors. Integrating this into an NDIR methane gas sensing system achieves a 13 fold enhancement in the LOD.…”

“…3(a). The IR detector is a 500 µm square-type membrane and the thickness is of about 3.45 µm [26]. First, the pyroelectric IR detector consisting of the SiO2/Pt/PZT/Pt/Ta/SiNx multilayer is patterned (step 1 to 3).…”

Enhancing the sensitivity of a micro-diaphragm resonating sensor by effectively positioning the mass on the membrane

“…In our previous research, we examined sensing of the viscosity and density of blood by using a micro-diaphragm. Changes in the resonant frequency and quality factor resulted from loading the liquid onto the optimized loading side 12 . The study was, however, about the properties of the liquid and the highly optimistic case whereby the disadvantages of liquid detection were overcome by the ability to detect the properties of a liquid.…”