Vascular Pressure–Flow Measurement Using CB-PDMS Flexible Strain Sensor

Abstract

Regular monitoring of blood flow and pressure in vascular reconstructions or grafts would provide early warning of graft failure and improve salvage procedures. Based on biocompatible materials, we have developed a new type of thin, flexible pulsation sensor (FPS) which is wrapped around a graft to monitor blood pressure and flow. The FPS uses carbon black (CB) nanoparticles dispersed in polydimethylsiloxane (PDMS) as a piezoresistive sensor layer, which was encapsulated within structural PDMS layers and connected to stainless steel interconnect leads. Because the FPS is more flexible than natural arteries, veins, and synthetic vascular grafts, it can be wrapped around target conduits at the time of surgery and remain implanted for long-term monitoring. In this study, we analyze strain transduction from a blood vessel and characterize the electrical and mechanical response of CB-PDMS from 0-50% strain. An optimum concentration of 14% CB-PDMS was used to fabricate 300-μm thick FPS devices with elastic modulus under 500 kPa, strain range of

Using a conductive sphere as a probe to characterize the sensitivity of soft piezoresistive films

“…Thus, GF = ∆ ρ /( ρ min ∆ ε ). Gage factors and resistivity values reported in literature for carbon black doped PDMS are in the range of approximately 1–10 for gage factor and 0.1–1 for resistivity, both in the vicinity of the values reported here 11,44–46 . Additionally, the reported trends are also in agreement with our result, in that both the resistivity and gage factor increase with decreasing carbon black weight percentage.…”

Properties and Applications of PDMS for Biomedical Engineering: A Review

“…This technique allows for verification of if there was or not a change in the wettability of the PDMS after certain treatments [ 19 , 39 , 42 , 94 ]; Nanoindentation offers the possibility of studying mechanical properties of the outermost layer of PDMS, which is susceptible to destruction due to different treatments, such as UV irradiation [ 95 ]; Tensile testing allows Young Modulus measurement of PDMS. The Young Modulus can be affected by treatments that may be applied to PDMS, by hardening temperature and time, and by the mixing ratio used to fabricate the PDMS samples [ 42 , 96 , 97 ]; X-ray photoelectron spectroscopy (XPS) is a technique based on the photoelectric effect, which allows identification of the elemental composition of the material. This method is useful when it is needed to verify if any changes in surface composition occurred after the PDMS received any treatment [ 38 , 39 , 98 ]; Fourier Transform infrared spectroscopy (FTIR) is a method used to obtain the infrared spectrum of absorption or transmission of the PDMS sample.…”

“…Tensile testing allows Young Modulus measurement of PDMS. The Young Modulus can be affected by treatments that may be applied to PDMS, by hardening temperature and time, and by the mixing ratio used to fabricate the PDMS samples [42,96,97]; • X-ray photoelectron spectroscopy (XPS) is a technique based on the photoelectric effect, which allows identification of the elemental composition of the material. This method is useful when it is needed to verify if any changes in surface composition occurred after the PDMS received any treatment [38,39,98];…”

Recent Advances in Printing Technologies of Nanomaterials for Implantable Wireless Systems in Health Monitoring and Diagnosis

“…applied stencil printing to form a flexible and implantable pulsation sensor for monitoring blood flow and pressure on vascular vessels or grafts. [ 92 ] The carbon black nanoparticles (CB) dispersed in polydimethylsiloxane (PDMS) were stencil‐printed and encapsulated by structural PDMS layers (Ecoflex). The patterned mylar stencil was used to form 0.1 mm thick traces of CB‐PDMS.…”