Matching Items (2)
Description
Peripheral Vascular Disease (PVD) is a debilitating chronic disease of the lower extremities particularly affecting older adults and diabetics. It results in reduction of the blood flow to peripheral tissue and sometimes causing tissue damage such that PVD patients suffer from pain in the lower legs, thigh and buttocks after activities. Electrical neurostimulation based on the "Gate Theory of Pain" is a known to way to reduce pain but current devices to do this are bulky and not well suited to implantation in peripheral tissues. There is also an increased risk associated with surgery which limits the use of these devices. This research has designed and constructed wireless ultrasound powered microstimulators that are much smaller and injectable and so involve less implantation trauma. These devices are small enough to fit through an 18 gauge syringe needle increasing their potential for clinical use. These piezoelectric microdevices convert mechanical energy into electrical energy that then is used to block pain. The design and performance of these miniaturized devices was modeled by computer while constructed devices were evaluated in animal experiments. The devices are capable of producing 500ms pulses with an intensity of 2 mA into a 2 kilo-ohms load. Using the rat as an animal model, a series of experiments were conducted to evaluate the in-vivo performance of the devices.
ContributorsZong, Xi (Author) / Towe, Bruce (Thesis advisor) / Kleim, Jeffrey (Committee member) / Santello, Marco (Committee member) / Arizona State University (Publisher)
Created2014
Description
Bioimpedance measurements have been long used for monitoring tissue ischemia and blood flow. This research employs implantable microelectronic devices to measure impedance chronically as a potential way to monitor the progress of peripheral vascular disease (PVD). Ultrasonically powered implantable microdevices previously developed for the purposes of neuroelectric vasodilation for therapeutic treatment of PVD were found to also allow a secondary function of tissue bioimpedance monitoring. Having no structural differences between devices used for neurostimulation and impedance measurements, there is a potential for double functionality and closed loop control of the neurostimulation performed by these types of microimplants. The proposed technique involves actuation of the implantable microdevices using a frequency-swept amplitude modulated continuous waveform ultrasound and remote monitoring of induced tissue current. The design has been investigated using simulations, ex vivo testing, and preliminary animal experiments. Obtained results have demonstrated the ability of ultrasonically powered neurostimulators to be sensitive to the impedance changes of tissue surrounding the device and wirelessly report impedance spectra. Present work suggests the potential feasibility of wireless tissue impedance measurements for PVD applications as a complement to neurostimulation.
ContributorsCelinskis, Dmitrijs (Author) / Towe, Bruce (Thesis advisor) / Greger, Bradley (Committee member) / Sadleir, Rosalind (Committee member) / Arizona State University (Publisher)
Created2015