Sensorless measurement of pulsatile flow rate using a disturbance force observer in a magnetically levitated centrifugal blood pump during ventricular assistance

2010 ◽  
Vol 21 (1) ◽  
pp. 33-39 ◽  
Author(s):  
Chi Nan Pai ◽  
Tadahiko Shinshi ◽  
Akira Shimokohbe
Keyword(s):  
Flow Rate ◽  
Pulsatile Flow ◽  
Blood Pump ◽  
Centrifugal Blood Pump ◽  
Magnetically Levitated ◽  
Ventricular Assistance

Effects of gravity on flow rate estimations of a centrifugal blood pump using the eccentric position of a levitated impeller

2020 ◽  
Vol 43 (12) ◽  
pp. 774-781
Author(s):  
Shuya Shida ◽  
Toru Masuzawa ◽  
Masahiro Osa
Keyword(s):  
Flow Rate ◽  
Ventricular Assist Devices ◽  
Blood Pump ◽  
Accurate Estimation ◽  
Ventricular Assist ◽  
Centrifugal Blood Pump ◽  
Assist Devices ◽  
Flow Estimation ◽  
Magnetically Levitated ◽  
Gravity Direction

Implantable ventricular assist devices are a type of mechanical circulatory support for assisting the pumping of the heart. Accurate estimation of the flow rate through such devices is critical to ensure effective performance. A novel method for estimating the flow rate using the passively stabilized position of a magnetically levitated impeller was developed by our group. However, the performance of the method is affected by the gravity vector, which depends on the patient’s posture. In this study, the effects of gravity on the flow estimation method are analyzed, and a compensation method is proposed. The magnetically levitated impeller is axially suspended and radially restricted by passive stability in a centrifugal blood pump developed by our group. The gravity effects were evaluated by analyzing the relationships between the radial position of the magnetically levitated impeller and the flow rate with respect to the gravity direction. Accurate estimation of the flow rate could not be achieved when the direction of gravity with respect to impeller was unknown. A mean absolute error of up to 4.89 L/min was obtained for flow rate measurement range of 0–5 L/min. However, analysis of the equilibrium of forces on the passively stabilized impeller indicated that the effects of gravity on the flow estimation could be compensated by performing additional measurements of the gravity direction with respect to impeller. The method for compensating the effects of gravity on the flow estimation should improve the performance of therapy with the implantable ventricular assist devices.

An experimental performance comparison of Newtonian and non-Newtonian fluids on a centrifugal blood pump

2022 ◽  
pp. 095441192110576
Author(s):  
Ahmet Onder ◽  
Rafet Yapici ◽  
Omer Incebay
Keyword(s):  
Flow Rate ◽  
Rotational Speed ◽  
Performance Test ◽  
Newtonian Fluids ◽  
Friction Reduction ◽  
Blood Pump ◽  
Actual Performance ◽  
Centrifugal Blood Pump ◽  
Working Fluids ◽  
Pump Performance

The use of substitute fluid with similar rheological properties instead of blood is important due to ethical concerns and high blood volume consumption in pump performance test before clinical applications. The performance of a centrifugal blood pump with hydrodynamic journal bearing is experimentally tested using Newtonian 40% aqueous glycerin solution (GS) and non-Newtonian aqueous xanthan gum solution of 600 ppm (XGS) as working fluids. Experiments are performed at four different rotational speeds which are 2700, 3000, 3300, and 3600 rpm; experiments using GS reach between 8.5% and 37.2% higher head curve than experiments using the XGS for every rotational speed. It was observed that as the rotational speed and flow rate increase, the head curve difference between GS and XGS decreases. This result can be attributed to the friction reduction effect when using XGS in experiments at high rotation speed and high flow rate. Moreover, due to different fluid viscosities, differences in hydraulic efficiency were observed for both fluids. This study reveals that the use of Newtonian fluids as working fluids is not sufficient to determine the actual performance of a blood pump, and the performance effects of non-Newtonian fluids are remarkably important in pump performance optimizations.

Early In Vivo Evaluation of Ventricular Assistance With a Miniature Centrifugal Blood Pump (TinyPump) in Rabbits

ASAIO Journal ◽  
2010 ◽  
Vol 56 (3) ◽  
pp. 254-259 ◽  
Author(s):  
Taketoshi Maeda ◽  
Yoshihisa Tanoue ◽  
Mariko Kobayashi ◽  
Hironori Baba ◽  
Yuichi Shiokawa ◽  
...  
Keyword(s):  
Blood Pump ◽  
In Vivo Evaluation ◽  
Centrifugal Blood Pump ◽  
Ventricular Assistance

Estimation of the radial force using a disturbance force observer for a magnetically levitated centrifugal blood pump

2009 ◽  
Vol 224 (7) ◽  
pp. 913-924 ◽  
Author(s):  
C N Pai ◽  
T Shinshi ◽  
A Shimokohbe
Keyword(s):  
Rotational Speed ◽  
Fluid Dynamic ◽  
Radial Force ◽  
Magnetic Bearing ◽  
Blood Pump ◽  
Working Fluid ◽  
Computational Fluid Dynamic Analysis ◽  
Centrifugal Blood Pump ◽  
Magnetically Levitated ◽  
Radial Thrust

Evaluation of the hydraulic forces in a magnetically levitated (maglev) centrifugal blood pump is important from the point of view of the magnetic bearing design. Direct measurement is difficult due to the absence of a rotor shaft, and computational fluid dynamic analysis demands considerable computational resource and time. To solve this problem, disturbance force observers were developed, using the radial controlled magnetic bearing of a centrifugal blood pump, to estimate the radial forces on the maglev impeller. In order to design the disturbance observer, the radial dynamic characteristics of a maglev impeller were evaluated under different working conditions. It was observed that the working fluid affects the additional mass and damping, while the rotational speed affects the damping and stiffness of the maglev system. Based on these results, disturbance force observers were designed and implemented. The designed disturbance force observers present a bandwidth of 45 Hz. In non-pulsatile conditions, the magnitude of the estimated radial thrust increases in proportion to the flowrate, and the rotational speed has little effect on the force direction. At 5 l/min against 100 mmHg, the estimated radial thrust is 0.95 N. In pulsatile conditions, this method was capable of estimating the pulsatile radial thrust with good response.

Dynamic Characteristics of a Magnetically Levitated Impeller in a Centrifugal Blood Pump

2007 ◽  
Vol 31 (4) ◽  
pp. 301-311 ◽  
Author(s):  
Junichi Asama ◽  
Tadahiko Shinshi ◽  
Hideo Hoshi ◽  
Setsuo Takatani ◽  
Akira Shimokohbe
Keyword(s):  
Dynamic Characteristics ◽  
Blood Pump ◽  
Centrifugal Blood Pump ◽  
Magnetically Levitated
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