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Another example of a product currently under development is a maternity smart fabric bellyband to monitor uterine activity and assess fetal wellbeing. This project leverages conductive yarns, knitting technology and the use of a passive radio frequency identification (RFID) tag. The aim was to create of a wearable wireless telemetry device that reduces bulk, improves comfort and enables greater mobility in pregnant women. The wearable, battery-less wireless sensor would replace the current cumbersome wired probes for contractions and respiration monitoring. The first step in the bellyband design was to experiment with digital fabrication of different antenna shapes knitted with conductive yarns that connect to the passive RFID. We considered a multitude of conductive pathway designs for our antenna including the final design in the form of a folded dipole antenna.


Kapil Dandekar, PhD Drexel Wireless System Lab, Department of Electrical and Computer Engineering
College of Engineering, Drexel University
Adam Fontecchio, PhD Drexel Nanophotonics+ Lab, Department of Electrical and Computer Engineering
College of Engineering, Drexel University
Timothy Kurzweg, PhD Department of Electrical and Computer Engineering, College of Engineering, Drexel University
Owen Montgomery, PhD Obstetrics and Gynecology Department, College of Medicine, Drexel University

Funded by NSF’s Partnerships for Innovation (1430212, PI Dandekar); Drexel University and Wallace H. Coulter Endowment (PI Adam Fontecchio).


Patron D, Gedin K, Kurzweg T, Fontecchio A, Dion G, Dandekar KR. 2014. A wearable RFID sensor and effects of human body proximity. In: 2014 IEEE Benjamin Franklin Symposium on Microwave and Antenna Systems for Radar, Telecommunications, and Biomedical Applications; 2014 September 27; Philadelphia, PA.

  • Wearable electronics integrate smart sensors and compact computing systems into garments. In this paper, we discuss the design and simulation of a textile RFID sensor for wearable applications. The sensor comprises a textile folded dipole antenna, specifically designed for use with an inductively-coupled RFID microchip at 870 MHz. As opposed to conventional microchips, in this case the device does not need any physical soldering, making it very convenient for wearable applications. The numerical analysis was extended to evaluate the loading effects of human body proximity. For distances greater than 10 mm, the antenna maintains good impedance matching and a broadside radiation with a gain of about 2 dBi.

Patron D, Kurzweg T, Fontecchio A, Dion G, Dandekar KR. 2014. Wireless strain sensor through a flexible tag antenna employing inductively-coupled RFID microchip. In: 2014 IEEE 15th Annual Wireless and Microwave Technology Conference; 2014 June 6; Tampa, FL. Red Hook, NY: Curran Associates. p 161-163.

  • Intensity variations of the backscattered power from an RFID tag have been demonstrated to be a potential wireless solution to measure material deformation. This paper discusses the design and performance of a flexible tag antenna equipped with novel inductively-coupled RFID microchip for use as a wireless strain sensor. Dielectric characterization of a flexible substrate has been carried out to properly design and simulate the proposed antenna design. Due to the balanced nature of this radiating element, differential scattering parameter measurements were performed to characterize the antenna input impedance. Finally, measurements of the backscattered power as a function of radial deformations are also shown as a qualitative analysis of the strain sensing capabilities.