A Miniaturized Hemoretractometer for Blood Clot Retraction Testing

Abstract

Blood coagulation is a critical hemostatic process that must be properly regulated to maintain a delicate balance between bleeding and clotting. Disorders of blood coagulation can expose patients to the risk of either bleeding disorders or thrombotic diseases. Coagulation diagnostics using whole blood is very promising for assessing the complexity of the coagulation system and for global measurements of hemostasis. Despite the clinic values that existing whole blood coagulation tests have demonstrated, these systems have significant limitations that diminish their potential for point-of-care applications. In this work, we leverage recent advancements in device miniaturization using functional soft materials to develop a miniaturized clot retraction force assay device termed mHemoRetractoMeter (mHRM). The mHRM is capable of precise measurements of dynamic clot retraction forces in real time using minute amounts of whole blood. To further demonstrate the clinical utility of the mHRM, we conduct systematic studies using the mHRM to examine the effects of assay temperature, treatments of clotting agents, and pro- and anti-coagulant drugs on clot retraction force developments of whole blood samples. The mHRM's low fabrication cost, small size, and consumption of only minute amounts of blood samples make the technology promising as a point-of-care tool for future coagulation monitoring.

Advanced Microfluidic Device Designed for Cyclic Compression of Single Adherent Cells

“…PDMS membrane was modeled as a linearly elastic material. It was shown previously that PDMS with base and curing agent ratio of 20:1 is linearly elastic even under large deformation (Li et al, 2016 ). The block displacements were determined for 27 conditions where we permutated the values of the three variables (Figure 2B ).…”

Carbon Nanotube Strain Sensor Based Hemoretractometer for Blood Coagulation Testing

“…At a given force, smaller spring constant leads to greater beam displacements and thus a higher measurement sensitivity. From the classical beam theory 16 , the beam spring constant K is calculated as K = 16 Eδ 3 W / L 3 , where E is the Young’s modulus of PDMS, and δ , W , and L are the beam thickness, width, and length, respectively. Given their small geometries, micropillars on the PDMS force-sensing beam had negligible impact on the beam spring constant K .…”

“…As expected, CNT-mHRM devices captured dynamic clot retraction (Figure 4a) and revealed two major CRF development phases, the reaction phase and contraction development phase (Figure 4b). 3, 16 From the onset of our assays ( T = 0) to the end of reaction phase ( T = T r ; designated as reaction time), there was an active coagulation cascade till fibrin network was formed and activated platelets started interacting with fibrin and contracting, leading to rapid increase of CRF in the contraction development phase. Here we defined growth rate of CRF G CRF and CRF at 60 min CRF 60 as $G_{\mathrm{italicCRF}}={\phantom{true\mid }\frac{\mathrm{italicdCRF}}{\mathrm{italicdT}}\mid }_{T=T_r}$ and CRF 60 = CRF ∣ T =60 min .…”

Preventive Effects of Catechins on Cardiovascular Disease

“…NO is a fundamental determinant for maintaining vascular function. Catechins can stabilize NO when blood vessels are damaged, and 10 μg/mL of EC could cause the phosphorylation of nitric oxide synthase serine residues 633 and 1177, as well as the dephosphorylation of threonine residues 495, which can strengthen the activity of eNOS and increase the release of NO, and then delay the signals from hemodynamic changes accepted by endothelial cells in the body, which avoid endothelial cells from causing a strong stress response in order to reduce the formation of blood clots [54,55]. Improvements in vascular endothelial dysfunction might potentially contribute to the beneficial effects of tea catechins in the treatment of patients with hypertension.…”