In this communication, the simulation and experimental results of a novel wideband wearable circularly polarized textile antenna for low-power transmission in the 2.45 GHz ISM band are presented. The wide impedance and axial ratio bandwidths make it perfect for low microwave power transmission to a wearable sensor system. The antenna is flexible, robust and light weight so that it can be easily integrated into clothes. It is shown that the circularly polarized textile antenna has a 3-dB axial ratio bandwidth of 564 MHz (23%) and a dB impedance bandwidth of 1086 MHz (44%) on a human body with the maximum gain of 4.9 dBic. Lastly, the textile antenna is employed on the battery-less temperature sensor system on a human arm to demonstrate the effective power transmission over a metre distance.

In this paper, the development of a fully implantable wireless sensor able to provide continuous real-time accurate pressure measurements is presented. Surface Acoustic Wave (SAW) technology was used to deposit resonators on crystalline quartz wafers; the wafers were then assembled to produce a pressure sensitive device. Excitation and reading via a miniature antenna attached to the pressure sensor enables continuous external interrogation. The main advantages of such a configuration are the long term stability of quartz and the low power necessary for the interrogation, which allows 24/7 interrogation by means of a hand-held, battery powered device. Such data are of vital importance to clinicians monitoring and treating the effects of hypertension and heart failure. A prototype was designed and tested using both a bio-phantom test rig and an animal model. The pressure traces for both compare very well with a commercially available catheter tip pressure transducer. The work presented in this paper is the first known wireless pressure data from the left ventricle of the heart of a living swine.

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Modern analog circuits are heavily dependent on inductor performance, where the poor inductor quality factor ( ) of silicon processes leads to degradation in circuit efficacy, especially at RF and microwave frequencies. Several techniques have been proposed to enhance the of integrated on-chip inductors, but the most effective method of improvement is to lower the series resistance by increasing the inductor metal thickness. This paper presents the most cost-effective method of achieving a thick metal by using a standard 0.18-m multilayer BiCMOS process. An expanded physically based model for multiple-metal stacked inductors is presented, which expands on previous research to show the effects and limitations of stacking two, three, and four metal layers in a five-metal-layer process. The excellent accuracy of this geometrical model is illustrated with respect to a range of inductor designs showing that an improvement in of more than 50% may be achieved. Due to the increased parasitics in multilayer structures, the improvement is very frequency dependent, which is clearly predicted with the expanded model. The predictive capability of the model is further used to provide detailed insight into the effectiveness of a patterned ground shield for different substrate characteristics. This predictive ability will contribute greatly to first time right inductor designs and eliminate the expensive and time-consuming fabrication iterations required to fine tune other inductor models.Index Terms-Integrated stacked inductor model, patterned ground shield (PGS), improvement, prediction.

The present article presents a method for assessing the radial stiffness of nitinol stents. An idealized stent model was created, and its radial stiffness was calculated by means of finite element modeling. The calculations were validated against experimental measurements. The variation of radial stiffness with geometrical dimensions was calculated, and the effect of increasing radial stiffness on endovascular deployment was analyzed. Peak tensile and compressive stresses as well as stent penetration were calculated in the case of an idealized pulmonary artery model having realistic dimensions as well as stiffness. The results of stress calculations were compared with a second set of simulations, where an idealized behavior of the stent (uniform expansion to a theoretical contact diameter) was modeled. The results show how in reality nitinol stents behave in a non-ideal way, having a non-uniform expansion and exerting non-uniform pressure on the contact areas with the artery. Such non-ideality decreases though with the increase in radial stiffness. The radial force alone may be insufficient in describing the stent-artery interaction, and numerical modeling proves to be necessary for capturing such complexity.