A Flexible Double Helix Inductive Antenna for RFID Vascular Flow Sensing.

Area of Science:

• Biomedical Engineering
• Implantable Medical Devices
• Biosensors

Background:

• Traditional blood-contacting sensors risk complications like clotting and platelet deposition.
• Need for minimally invasive, implantable sensors for continuous vascular monitoring.
• Existing radio frequency identification (RFID) systems lack flexible, implantable antenna designs for vascular applications.

Purpose of the Study:

• To develop a batteryless, implantable blood-flow sensor with RFID readout for surgical implantation around blood vessels.
• To create a flexible sensor system that minimizes blood contact and associated complications.
• To enable real-time monitoring of blood flow and vascular distension.

Main Methods:

• Developed a flexible, cuff-like sensor architecture for non-invasive implantation around arteries, veins, or grafts.
• Engineered a novel split-double helix antenna (DHA) for flexible RFID data/power transmission.
• Fabricated a piezoresistive carbon black-polydimethylsiloxane (PDMS) nanocomposite flexible pulsation sensor (FPS).
• Integrated a commercial RFID chip for real-time data readout to an external transceiver.

Main Results:

• Demonstrated functional implantable DHA systems capable of wrapping around vessels (3-8 mm diameter).
• Achieved a typical coupling coefficient of 0.007 for DHAs at 5 cm from a reader.
• Successfully monitored blood flow rates from 200 to 400 mL/min in a vascular phantom with simulated stenosis.
• Showcased the capacity to detect flow changes as low as 10 mL/min with a 12 Hz sample rate.

Conclusions:

• The batteryless, implantable blood-flow sensor system offers a promising solution for monitoring vascular health without direct blood contact.
• The novel flexible DHA and FPS design facilitates minimally invasive surgical implantation and reliable blood flow measurement.
• This technology has the potential to improve patient outcomes by enabling continuous, real-time assessment of blood flow in critical vascular applications.