RF-Powered Stent With Integrated Circuit Breaker for Safeguarded Wireless Hyperthermia Treatment

Abstract

This paper presents a wireless, electrothermally active stent with an integrated temperature limiter toward the application to endohyperthermia treatment of restenosis, a major post-stenting complication. A stent-based resonant circuit serves as a frequency selective wireless heater controlled using a tuned radio-frequency (RF) electromagnetic field radiated externally, applying local thermal stress to the stented site to suppress in-stent restenosis. A biocompatible 1.5 × 2 × 0.6-mm 3 chip of micro circuit breaker with an embedded capacitor is developed and integrated with the stent to establish the resonant circuitry with a series-connected micro breaker. A micromachined shapememory-alloy cantilever serves as a thermoresponsive switch in the chip that opens/closes the circuit depending on the stent temperature, automatically preventing the stent from overheating in a fully passive manner. Wireless heating tests of the prototypes deployed into artificial artery using commercial balloon catheters demonstrate the designed function of the circuit breaker, regulating the stent temperature within 50°C-66°C when excited in air at an output RF power of 320 mW, which heats the device to 78°C without the breaker. Their performance in physiological saline is also tested and discussed in detail. The experimental results validate the device concept and approach toward enabling reliable and safeguarded hyperthermia treatment through wireless stents.[2015-0007]

Health Care Monitoring and Treatment for Coronary Artery Diseases: Challenges and Issues

“…MEMS transducers and other microsystems offer a practical path to realizing electro thermally active stents with temperature regulation and controls, which enable their reliable and safe use in endohyperthermia treatments of restenosis [ 44 , 101 ].…”

“… The pressure sensor using a stent as an antenna integrated with MEMS capacitive: ( A ) Completed active stent device with the stent terminal on which the interconnect wire was bonded. Reproduced with permission [ 44 ], copyright 2020, IEEE; ( B ) fabricated LC-tank stent devices integrated with capacitive pressure sensors and a device coated with Parylene C; ( C ) conceptual diagram of wireless sensing of vascular conditions through the sensor-integrated smart stent. Reproduced with permission [ 41 ], copyright 2020, Springer Nature.…”

A Single-Connector Stent Antenna for Intravascular Monitoring Applications

“…The strut length, crown length, and connector length are the lengths of the strut, crown, and connector shown in Figure 2. Furthermore, the length should be in the range of 10 to 20 mm, and the diameter, in the range of 2 to 10 mm due to the sizes of vessels [7,8]. In addition, this frequency range falls in the range of the ISM band, and a high operation frequency is beneficial for implantable antennas [23].…”

“…The re-narrowing of blood vessels hinders the blood flow and can cause severe problems. These issues can be alleviated by eluting drugs [4,5], manipulating shear stresses on the vessel walls [6], or heating the re-narrowing regions to suppress the growth of vascular smooth muscle cells [7,8].…”

“…Thus, it is necessary to miniaturize implantable electronic devices and communication systems. Various wireless power/data communications approaches for smart stents have been investigated, including passive LC-resonant antennas [7,8,9,12,17,24,25,26], miniaturized packaged antennas [20], RFIC [11], and active stent antennas [10,14,15,19,23]. LC-resonant antennas are composed of metallic stents acting as inductors and additional capacitors forming LC resonant circuits.…”