Stretchable electrochemical impedance sensors for intravascular detection of lipid-rich lesions in New Zealand White rabbits

Abstract

Flexible electronics have enabled catheter-based intravascular sensing. However, real-time interrogation of unstable plaque remains an unmet clinical challenge. Here, we demonstrate the feasibility of stretchable electrochemical impedance spectroscopy (EIS) sensors for endoluminal investigations in New Zealand White (NZW) rabbits on diet-induced hyperlipidemia. A parylene C (PAC)-based EIS sensor mounted on the surface of an inflatable silicone balloon affixed to the tip of an interrogating catheter was deployed 1) on the explants of NZW rabbit aorta for detection of lipid-rich atherosclerotic lesions, and 2) on live animals for demonstration of balloon inflation and EIS measurements. An input peak-to-peak AC voltage of 10 mV and sweeping-frequency from 300 kHz to 100 Hz were delivered to the endoluminal sites. Balloon inflation allowed EIS sensors to be in contact with endoluminal surface. In the oxidized low-density-lipoprotein (oxLDL)-rich lesions from explants of fat-fed rabbits, impedance magnitude increased significantly by 1.5-fold across the entire frequency band, and phase shifted ~5 degrees at frequencies below 10 kHz. In the lesion-free sites of the normal diet-fed rabbits, impedance magnitude increased by 1.2-fold and phase shifted ~5 degrees at frequencies above 30 kHz. Thus, we demonstrate the feasibility of stretchable intravascular EIS sensors for identification of lipid rich lesions, with a translational implication for detecting unstable lesions.

Electrical and Mechanical Strategies to Enable Cardiac Repair and Regeneration

“…With the recent development of flexible and stretchable micro/nanotechnologies [58, 94, 116, 117], close-loop systems to simultaneously “train and screen” ESC- and iPSC-CMs are of interest. Microfluidic-based bioreactors which offer both “training and screening” functions are also conducive to cardiac drug discovery and screening [52, 118].…”

Ultrasonic transducer-guided electrochemical impedance spectroscopy to assess lipid-laden plaques

“…Built on our prior intravascular techniques [18, 45], the catheter-based dual sensors cannulate through aortas to reach the lesion sites for detection (Figure 1A). While advancing, the balloon (Advanced Polymers, Salem, NH, USA) is deflated (inset of Figure 1A) and the whole diameter of the sensor is 2.3 mm.…”

“…The resistance and reactance value of the impedance is represented as a resister, R , and a capacitor, C (Figure 2A). Contact impedance, Z C , at the interface between the electrode and tissue, is not negligible in most cases, and is taken into account in the measuring system as previously reported [18, 45]. …”

“…We further established the application of EIS strategy to detect oxLDL-rich fibroatheroma using explants of human coronary, carotid, and femoral arteries [15]. The regions of elevated EIS correlated with intimal thickening detected via high-frequency (60 MHz) IVUS imaging and by prominent oxLDL staining [18]. …”

Energy Harvesting: A Toxic Free and Reliable Power Source for Implantable Microsystems

“…Thus, long term stability during use, predictable performance, high volumetric energy density and outstanding reliability are key characteristics that define successful systems for biomedical implants [1]. Since the introduction of first cardiac implant in 1972, a variety of battery systems have been developed for implantable medical devices that utilize lithium metal anodes with cathode systems including iodine (Li/I2) [2][3][4], manganese oxide (Li/MnO2) [5,6], carbon monofluoride (Li/CFx) [7,8], silver vanadium oxide (Li/SVO) [9,10] and hybrid cathodes using both carbon monofluoride and silver vanadium oxide (Li-CFx-SVO) [11,12]. The specification of these batteries is presented in Table 1.…”