Browsing by Subject "Vibrations"

Now showing 1 - 6 of 6

Open Access
Assessment of silicon, glass, FR4, PDMS and PMMA as a chip material for acoustic particle/cell manipulation in microfluidics
(2023-03) Açıkgöz, Hande N.; Karaman, A.; Şahin, M. Akif; Çaylan, Ö. R.; Büke, G. C.; Yıldırım, E.; Eroğlu, İ. C.; Erson-Bensan, A. E.; Çetin, Barbaros; Özer, M. B.
In the present study, the capabilities of different chip materials for acoustic particle manipulation have been assessed with the same microfluidic device architecture, under the same actuator and flow conditions. Silicon, glass, epoxy with fiberglass filling (FR4), polydimethylsiloxane (PDMS) and polymethyl methacrylate (PMMA) are considered as chip materials. The acoustophoretic chips in this study were manufactured with four different fabrication methods: plasma etching, chemical etching, micromachining and molding. A novel chip material, FR4, has been employed as a microfluidic chip material in acoustophoretic particle manipulation for the first time in literature, which combines the ease of manufacturing of polymer materials with improved acoustic performance. The acoustic particle manipulation performance is evaluated through acoustophoretic focusing experiments with 2μm and 12μm polystyrene microspheres and cultured breast cancer cell line (MDA-MB-231). Unlike the common approach in the literature, the piezoelectric materials were actuated with partitioned cross-polarized electrodes which allowed effective actuation of different family of chip materials. Different from previous studies, this study evaluates the performance of each acoustophoretic device through the perspective of synchronization of electrical, vibrational and acoustical resonances, considers the thermal performance of the chip materials with their effects on cell viability as well as manufacturability and scalability of their fabrication methods. We believe our study is an essential work towards the commercialization of acoustophoretic devices since it brings a critical understanding of the effect of chip material on device performance as well as the cost of achieving that performance.
Open Access
Dynamic Boundary Control of a Euler-Bernoulli Beam
(Institute of Electrical and Electronics Engineers, 1992) Morgül, Ö.
We consider a flexible beam clamped to a rigid base at one end and free at the other end. To stabilize the beam vibrations, we propose a dynamic boundary force control and a dynamic boundary torque control applied at the free end of the beam. We prove that with the proposed controls, the beam vibrations decay exponentially. The proof uses a Lyapunov functional based on the energy functional of the system. © 1992 IEEE
Open Access
Guest Editorial Special Section on Sensor Applications
(2013) Gurkan, D.; Flammini, A.
The six papers in this special section focus on sensor technologies and applications for their use.
Open Access
Harmonic cantilevers for nanomechanical sensing of elastic properties
(IEEE, 2003-06) Şahin, O.; Yaralıoğlu, G.; Grow, R.; Zappe, S. F.; Atalar, Abdullah; Quate, C.; Solgaard, O.
We present a micromachined scanning probe cantilever, in which a specific higher order flexural mode is designed to be resonant at an exact integer multiple of the fundamental resonance frequency. We have demonstrated that such cantilevers enable sensing of nonlinear mechanical interactions between the atomically sharp tip at the free end of the cantilever and a surface with unknown mechanical properties in tapping-mode atomic force microscopy.
Open Access
Piezoelectric power generation using heart motion
(2006) Afacan, Onur
The presence of pacemakers and implantable cardioverter-defibrillators (ICD) is considered historically a contraindication to magnetic resonance (MR) imaging. Main reason behind this contraindication is the current induced on the pacing leads during the MRI examination which may damage the cardiac tissues by heating or the pulse generator of the pacemaker with a reverse current. In this thesis an approach towards the solution of this problem is stated. It has been shown in previous work that replacing the pacing leads with fiber-optic cables minimizes the current induced on the leads. Drawback of this system is the increase in the power consumption of the pacemaker because of the fiber-optic cables and also necessity of an additional pulse generator circuitry near the heart. In this thesis, feasibility of using a piezoelectric power generator for compensating the increased power consumption is investigated. A novel piezoelectric geometry increasing the effective length in a given volume is designed. With this device the resonance frequency of the generator was decreased and the power output for a given volume is increased compared to standard rectangular piezoelectric bimorphs. When connected to a simple heart phantom the novel design produced 2.83 microwatts power whereas the standard rectangular bimorphs produced less than 1 microwatts. Although the output power is increased with the novel design, it was not sufficient to power a pulse generator circuitry that will be used to pace the heart.
Open Access
Sensors in assisted living: a survey of signal and image processing methods
(Institute of Electrical and Electronics Engineers, 2016-03) Erden, F.; Velipasalar, S.; Alkar, A. Z.; Çetin, A. Enis
Our society will face a notable demographic shift in the near future. According to a United Nations report, the ratio of the elderly population (aged 60 years or older) to the overall population increased from 9.2% in 1990 to 11.7% in 2013 and is expected to reach 21.1% by 2050 [1]. According to the same report, 40% of older people live independently in their own homes. This ratio is about 75% in the developed countries. These facts will result in many societal challenges as well as changes in the health-care system, such as an increase in diseases and health-care costs, a shortage of caregivers, and a rise in the number of individuals unable to live independently [2]. Thus, it is imperative to develop ambient intelligence-based assisted living (AL) tools that help elderly people live independently in their homes. The recent developments in sensor technology and decreasing sensor costs have made the deployment of various sensors in various combinations viable, including static setups as well as wearable sensors. This article presents a survey that concentrates on the signal processing methods employed with different types of sensors. The types of sensors covered are pyro-electric infrared (PIR) and vibration sensors, accelerometers, cameras, depth sensors, and microphones.