• Title/Summary/Keyword: Implantable sensors

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A Development of Eddy Current Sensor System for An Axial-flow type Blood Pump with The Magnetic Bearing (축류형 인공심장의 자기베어링 제어를 위한 와전류 센서 시스템 개발)

  • Ahn, C.B.;Moon, K.C.;Jeong, G.S.;Nam, K.W.;Lee, J.J.;Sun, K.
    • Journal of Biomedical Engineering Research
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    • v.28 no.2
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    • pp.310-315
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    • 2007
  • The axial-flow type blood pump(XVAD) which has been developed in our group consists of mechanical parts (an impeller, a diffuser and a flow straightener) and electrical parts (a motor and a magnetic bearing). The magnetic bearing system fully levitates the impeller to remove mechanical coupling with other parts of the pump with constant gap, which needs non-contact type gap sensing. Conventional gap sensors are too large to be adopted to the implantable axial -flow type blood pump. Thus, in this paper, the compact eddy current type gap sensor system proper for the implantable axial-flow type blood pump was developed and its performance was evaluated in vitro. The developed eddy current type gap sensor system is a transformer type and has a differential probe. Sensor coil(probe) has small dimensions(6 mm diameter, 2 mm thickness) and its optimal inductance was determined as 0.068 mH for the measurement range of $0\sim3mm$. It could be manufactured with 130 turns of the 0.04 mm diameter copper coil. The characteristics of the developed eddy current type gap sensor system was evaluated by in vitro experiment. At experiment, it showed satis(actory performance to apply to the magnetic bearing system of the XVAD. It could measure the gap up to 3mm, but the linearity was decreased at the range of $1.8\sim3.0mm$. Moreover, it showed no difference in different media such as the water and the blood at the temperature range of $35\sim40^{\circ}C$.

Design of Capacitive Sensors for Blood Vessel Condition Using FEA Simulation; For Developing of an Implantable Telemetry System to Monitoring the Arterial Change (FEA 시뮬레이션을 이용한 혈관 상태 측정용 커패시티브 센서 설계; 체내 동맥 혈관 변화 모니터링이 가능한 이식형 텔레메트리 시스템 개발을 위한)

  • Kang, So Myoung;Lee, Jae Ho;Wei, Qun
    • Journal of Korea Multimedia Society
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    • v.22 no.11
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    • pp.1280-1287
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    • 2019
  • For developing a wireless implantable device to monitoring the artery variation in real-time. The concept of a special vessel variation measurement capacitive sensor is presented in this paper. The sensor consists of two part; main sensor to measuring the arterial variation, and reference sensor is used to improve the accuracy of the capacitance value variation. Before sensor manufacture, a model of the sensor attached on the artery was designed in 3D to conduct in the FEA simulation to validate the validity and feasibility of the idea. The artery model was designed as layered structures and made of collagenous soft tissues with intima inside, followed by the media and the adventitia. Also, a grease layer was designed in the inner of the arterial wall to imitate the clogged arteries. The simulation was divided into two parts; sensor performance test by changing the diameter of the grease layer, and arterial wall tension test by changing the blood pressure. As the simulation results, the capacitance value measured by the proposed sensor is decreased follow the diameter of the grease increased. Also, large elastic deformation of the arterial wall since changing the blood pressure has been observed.

Vibration characteristic analysis of differential floating mass transducer using electrical model for fully-implantable middle ear hearing devices (전기 모델에 의한 완전 이식형 인공중이용 차동 전자 트랜스듀서의 진동 특성 해석)

  • Kim, Min-Woo;Kim, Min-Kyu;Seong, Ki-Woong;Lim, Hyung-Gyu;Jung, Eui-Sung;Han, Ji-Hun;Park, Il-Yong;Cho, Jin-Ho
    • Journal of Sensor Science and Technology
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    • v.16 no.3
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    • pp.165-173
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    • 2007
  • A differential floating mass transducer has been developed in Korea for fully implantable middle ear hearing devices (F-IMEHDs). In particular, the performance of a differential floating mass transducer (DFMT) is very important among the parts of the F-IMEHDs because the mechanical vibration generated by DFMT is delivered to the inner ear directly. In this paper, the electrical model is proposed to analyze the DFMT vibration characteristic using the mechanical model of the DFMT. The electrical model enables the simple analysis of DFMT vibration characteristics using a computer program. The proposed electrical model is simulated through PSpice as changing the values of passive elements in the electrical model. To verify the proposed model, the DFMT has been implemented on the basis of the simulated results and the experiment for vibration measurement has been carried out. Through the comparison, it is verified that the proposed model is useful to analyze the vibration characteristics of the DFMT.

Implantable Nerve Cuff Electrode with Conductive Polymer for Improving Recording Signal Quality at Peripheral Nerve (말초 신경 신호 기록의 효율성 개선을 위한 전도성 폴리머가 적용된 생체삽입형 커프형 신경전극)

  • Park, Sung Jin;Lee, Yi Jae;Yun, Kwang-Seok;Kang, Ji Yoon;Lee, Soo Hyun
    • Journal of Sensor Science and Technology
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    • v.24 no.1
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    • pp.22-28
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    • 2015
  • This study demonstrates a polyimide nerve cuff electrode with a conductive polymer for improving recording signal quality at peripheral nerve. The nerve cuff electrodes with platinum (Pt), iridium oxide (IrOx), and poly(3,4-ethylenedioxythiophene): p-toluene sulfonate (PEDOT:pTS) were fabricated and investigated their electrical characteristics for improving recorded nerve signal quality. The fabricated nerve cuff electrodes with Pt, IrOx, and PEDOT:pTS were characterized their impedance and CDC by using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. The impedance of PEDOT:pTS measured at 1 kHz was $257{\Omega}$, which was extremely lower than the value of the nerve cuff electrodes with IrOx ($15897{\Omega}$) and Pt ($952{\Omega}$), respectively. Furthermore, the charge delivery capacity (CDC) of the nerve cuff electrode with PEDOT:pTS was dramatically increased to 62 times than the nerve cuff electrode with IrOx. In ex-vivo test using extracted sciatic nerve of spaque-dawley rat (SD rat), the PEDOT:pTS group exhibited higher signal-to-interference ratio than IrOx group. These results indicated that the nerve cuff electrode with PEDOT:pTS is promising for effective implantable nerve signal recording.

Design of High Efficiency Differential Electromagnetic Type Transducer for Implantable Middle Ear System (이식형 인공중이 시스템을 위한 고효율 차동 전자 트랜스듀서의 설계)

  • Song, Byung-Seop;Ro, Chul-Kyun;Kim, Myoung-Nam;Cho, Jin-Ho
    • Journal of Sensor Science and Technology
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    • v.11 no.3
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    • pp.171-182
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    • 2002
  • The differential electromagnetic transducer for IME(implantable middle ear) system, which have two small permanent magnets glued with the same pole facing each other in the coil, has high vibration efficiency and does not influenced by external magnetic field. In this paper, using finite element method, highly efficient structure of the transducer was proposed and vibration force of the transducer was calculated by electromagnetic theory. And the necessary vibration force of transducer to transmit the sound signal to inner ear when the transducer is attached at stapes was calculated and the design parameters of the transducer were investigated. Using the parameters, the differential electromagnetic transducer was manufactured in small size to implant in confined human middle ear. And it was examined by unloaded and loaded vibration experiment using temporal bone sampled from cadaver.

Design of Implantable Middle Ear Hearing Aids Using an Electromagnetic Transducer (전자 트랜스듀서 방식에 의한 청각보조용 이식형 인공중이 시스템 설계)

  • Cho, Jin-Ho;Song, Byung-Seop;Kim, Myoung-Nam;Won, Chul-Ho;Park, Se-Kwang;Lee, Sang-Heun
    • Journal of Sensor Science and Technology
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    • v.6 no.6
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    • pp.466-475
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    • 1997
  • In this paper, an implantable middle ear hearing aids using an electromagnetic transducer which consists of a tiny coil and a magnet is designed, and objective design method to implement a vibrator of the electromagnetic type transducer is proposed. Sound characteristic of the electromagnetic type vibrator is excellent but power transfer rate is lower than that of a ceramic type. To improve power transfer efficiency of system, external and inner part of a middle ear system is designed using FM transmission method. We implemented an experimental set of the designed transducer, inner part, and outer part. Then, we measured vibration characteristics of a metal strip and a temporal bone of a dead body. As the results, we confirmed the advantage of FM method and showed that designed transducer could effectively transmit vibration of amplified input sound pressure to ossicle.

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Measurement of transmitted vibration to stapes and tympanic membrane by DFMT's vibration in implantable middle ear hearing devices (중이 이식형 보청기에서 DFMT의 진동에 의한 등골 및 고막 방향으로 전달되는 진동력 측정)

  • Lee, Myoung-Won;Seong, Ki-Woong;Lim, Hyung-Gyu;Kim, Min-Woo;Jung, Eui-Sung;Lee, Jang-Woo;Kim, Dong-Wook;Lee, Jyung-Hyun;Lee, Sang-Heun;Lee, Kyu-Yup;Cho, Jin-Ho
    • Journal of Sensor Science and Technology
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    • v.18 no.4
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    • pp.286-293
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    • 2009
  • The implantable middle ear hearing devices(IMEHDs) have been developed to overcome the conventional hearing aid's problem(ringing effect caused by the acoustic feedback, cosmetic problem, etc.). In the IMEHDs, the vibrating transducer is a key component because its vibration enables to hear for hearing impaired people. The vibrating transducer is implanted on ossicular chain by surgical operation. The coupling status between implanted transducer and ossicular chain has an effect on delivering vibrating force from transducer to stapes. Noninvasive method is required to investigate the output characteristics of IMEHDs after implementation. Recently, emitted sound pressure measuring method of tympanic membrane is proposed to investigate the output characteristics of IMEHDs. However, the relationship between displacement of stapes and sound pressure by tympanic membrane was not cleared. In this paper, displacement of stapes and sound pressure by tympanic membrane were measured using the differential floating mass transducer(DFMT) that implanted on the ossicular chain of the human temporal bone and physical ear model. Through the experiments results, the relationship between displacement of stapes and sound pressure by tympanic membrane was investigated.

Enhanced Secure Sensor Association and Key Management in Wireless Body Area Networks

  • Shen, Jian;Tan, Haowen;Moh, Sangman;Chung, Ilyong;Liu, Qi;Sun, Xingming
    • Journal of Communications and Networks
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    • v.17 no.5
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    • pp.453-462
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    • 2015
  • Body area networks (BANs) have emerged as an enabling technique for e-healthcare systems, which can be used to continuously and remotely monitor patients' health. In BANs, the data of a patient's vital body functions and movements can be collected by small wearable or implantable sensors and sent using shortrange wireless communication techniques. Due to the shared wireless medium between the sensors in BANs, it may be possible to have malicious attacks on e-healthcare systems. The security and privacy issues of BANs are becoming more and more important. To provide secure and correct association of a group of sensors with a patient and satisfy the requirements of data confidentiality and integrity in BANs, we propose a novel enhanced secure sensor association and key management protocol based on elliptic curve cryptography and hash chains. The authentication procedure and group key generation are very simple and efficient. Therefore, our protocol can be easily implemented in the power and resource constrained sensor nodes in BANs. From a comparison of results, furthermore, we can conclude that the proposed protocol dramatically reduces the computation and communication cost for the authentication and key derivation compared with previous protocols. We believe that our protocol is attractive in the application of BANs.

3-D Hetero-Integration Technologies for Multifunctional Convergence Systems

  • Lee, Kang-Wook
    • Journal of the Microelectronics and Packaging Society
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    • v.22 no.2
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    • pp.11-19
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    • 2015
  • Since CMOS device scaling has stalled, three-dimensional (3-D) integration allows extending Moore's law to ever high density, higher functionality, higher performance, and more diversed materials and devices to be integrated with lower cost. 3-D integration has many benefits such as increased multi-functionality, increased performance, increased data bandwidth, reduced power, small form factor, reduced packaging volume, because it vertically stacks multiple materials, technologies, and functional components such as processor, memory, sensors, logic, analog, and power ICs into one stacked chip. Anticipated applications start with memory, handheld devices, and high-performance computers and especially extend to multifunctional convengence systems such as cloud networking for internet of things, exascale computing for big data server, electrical vehicle system for future automotive, radioactivity safety system, energy harvesting system and, wireless implantable medical system by flexible heterogeneous integrations involving CMOS, MEMS, sensors and photonic circuits. However, heterogeneous integration of different functional devices has many technical challenges owing to various types of size, thickness, and substrate of different functional devices, because they were fabricated by different technologies. This paper describes new 3-D heterogeneous integration technologies of chip self-assembling stacking and 3-D heterogeneous opto-electronics integration, backside TSV fabrication developed by Tohoku University for multifunctional convergence systems. The paper introduce a high speed sensing, highly parallel processing image sensor system comprising a 3-D stacked image sensor with extremely fast signal sensing and processing speed and a 3-D stacked microprocessor with a self-test and self-repair function for autonomous driving assist fabricated by 3-D heterogeneous integration technologies.

Fabrication of Biofuel Cell Roll Using Flexible CNT Nanosheet Substrate (유연한 CNT Nanosheet 기판을 이용한 생체연료전지 Roll 제작)

  • Sung, Jungwoo;Lim, Geunbae
    • Journal of Sensor Science and Technology
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    • v.23 no.6
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    • pp.388-391
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    • 2014
  • The most promising application of the biofuel cells is implantable devices, so the biofuel cells should have an appropriate shape for the vascular vessel. We demonstrated the biofuel cell roll for using in tubes. MWNTs were aggregated by vacuum filtration on a nitrocellulose membrane filter, which was biocompatible and flexible. The MWNT aggregated nitrocellulose membrane used the electrodes of the biofuel cells because it was conductive as well as nanostuructured. Then, the membrane was rolled into the roll shape. The maximum power density of the biofuel cell roll was $7.9{\mu}W/cm^2$ at 153mV and 50 mM glucose. Also, the power density is expected to increase in its practical application if there is flow in the tube, which makes the transportation of fuel easy. The biofuel cell roll contacts with the wall of the tube, so flow in the tube does not disturb. Also, the biofuel cell roll has multi-layers offering more electroactive area.