• 대한의용생체공학회:의공학회지
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• 제37권5호
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• pp.168-177
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• 2016

In this paper we present an implantable pressure sensor to measure real-time blood pressure by monitoring mechanical movement of artery. Sensor is composed of inductors (L) and capacitors (C) which are formed by microfabrication and direct bonding on two biocompatible substrates (quartz). When electrical potential is applied to the sensor, the inductors and capacitors generates a LC resonance circuit and produce characteristic resonant frequencies. Real-time variation of the resonant frequency is monitored by an external measurement system using inductive coupling. Structural and electrical simulation was performed by Computer Aided Engineering (CAE) programs, ANSYS and HFSS, to optimize geometry of sensor. Ultrafast laser (femto-second) cutting and MEMS process were executed as sensor fabrication methods with consideration of brittleness of the substrate and small radial artery size. After whole fabrication processes, we got sensors of $3mm{\times}15mm{\times}0.5mm$. Resonant frequency of the sensor was around 90 MHz at atmosphere (760 mmHg), and the sensor has good linearity without any hysteresis. Longterm (5 years) stability of the sensor was verified by thermal acceleration testing with Arrhenius model. Moreover, in-vitro cytotoxicity test was done to show biocompatiblity of the sensor and validation of real-time blood pressure measurement was verified with animal test by implant of the sensor. By integration with development of external interrogation system, the proposed sensor system will be a promising method to measure real-time blood pressure.

• 대한의용생체공학회:의공학회지
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• 제28권4호
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• pp.539-548
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• 2007

In the paper, a wireless charger with the function of auto-shutdown for fully implantale middle ear hearing devices (F-IMEHD) has been designed. The wireless charger can communicate with an implant module to be turned off automatically shutdown after an internal rechargeable battery has been fully-charged by electromagnetic coupling using two coils. For the communication with an implant module, the wireless charger uses the load shift keying (LSK) method. But, the variation of the mutual inductance due to the different distance between two coils can cause the communication error in receiving the fully-charged signal from an implant module. To solve the problem, the implemented wireless charger has a variable reference generator for LSK communication. The wireless charger generates proper level of the reference voltage for a comparator using an ADC (analog-to-digital converter) and a DAC (digital-to-analog converter). Through the result of experiment, it has been confirmed that the presented wireless charger can detect signals from implantable module. And wireless charger can stop generating electromagnetic flux after an implanted battery has been fully charged in spite of variable coil distance according to different skin thickness.

• Journal of Pharmaceutical Investigation
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• 제25권2호
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• pp.109-116
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• 1995

For the administration of narcotic antagonist with short half-life and low patient compliance, the sustained release system using biodegradable matrix is effective. Polyphosphazenes are of considerable interest as biodegradable matrix systems for controlled release of drugs. In this study, biodegradable polyphosphazenes available for the sustained release implantable device were synthesized, and their application was examined. Poly[dichlorophosphazene] was synthesized by solution polymerization method and confirmed with IR spectrum. Poly[bis(ethyl glycinate) phosphazene] and poly[ (diethyl glutamate)-co-(ethyl glycinate)phosphazene] were then produced by substitution of amino acid alkyl esters for chloride side groups. Using these polymers, the implantable devices of 1 mm thickness and $10{\times}10\;mm$ size containing naloxone hydrochloride were prepared and their release and degradation profiles were measured. In the case of poly[bis(ethyl glycinate)phosphazene] with swelling characteristics, degradation rate was slower than the release rate, showing that the release rate is partly dependent on the swelling rate. In contrast, the degradation rate of polyl[(diethyl glutamate)-co-(ethyl glycinate)phosphazene] matrix was identical with release rate of naloxone hydrochloride. On the basis of these results, it is expected that these polymers can be applied to sustained release implantable systems delivering narcotic antagonist.

• Journal of Korean Neurosurgical Society
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• 제61권5호
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• pp.640-644
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• 2018

Objective : The purpose of this pilot study was to examine the safety and function of the newly developed cerebrospinal fluid (CSF) reservoir called the V-Port. Methods : The newly developed V-Port consists of a non-collapsible reservoir outlined with a titanium cage and a connector for the ventricular catheter to be assembled. It is designed to be better palpated and more durable to multiple punctures than the Ommaya reservoir. A total of nine patients diagnosed with leptomeningeal carcinomatosis were selected for V-Port insertion. Each patient was followed up for evaluation for a month after the operation. Results : The average operation time for V-Port insertion was 42 minutes and the average incision size was 6.6 cm. The surgical technique of V-Port insertion was found to be intuitive by all neurosurgeons who participated in the pilot study. There was no obstruction or leakage of the V-Port during intrathecal chemotherapy or CSF drainage. Also, there were no complications including post-operative intracerebral hemorrhage, infection and skin problems related to the V-Port. Conclusion : V-Port is a safe and an easy to use implantable CSF reservoir that addresses problems of other implantable CSF reservoirs. Further multicenter clinical trial is needed to prove the safety and the function of the V-Port.

• 센서학회지
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• 제12권6호
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• pp.249-257
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• 2003

환자의 체내에 삽입하여 여러 가지 생체정보를 무선으로 전송하는 형태의 텔레메트리 기술은 환자들의 불편함을 해소하고 기존의 진단 한계를 극복하는데 큰 기여를 할 것으로 기대되고 있다. 체내에서 생체신호를 외부의 전송하는 시스템의 경우, 정확한 질병지점을 판단하기 위해서는 체내의 텔레메트리 모듈의 위치를 체외에서 정착하게 파악할 수 있는 기술이 필수적이다. 본 논문에서는 8개의 안테나를 고정된 위치에 두고, 비선형 연립방정식의 해석을 통하여 체내에 삽입된 송신모듈의 위치를 결정하는 방법을 제안하고 해석하였다.

• The Korean Journal of Pain
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• 제22권1호
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• pp.74-77
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• 2009

Implantable intrathecal pump is one of the therapeutic options for intractable pain. A 24-year-old male with complex regional pain syndrome was suffering from right lower extremity pain. He had all modalities of treatment including spinal cord stimulator. However, his pain had been worse in the past 6 months. His visual analogue pain scale (VAS) was 8-10 and he could not sit or walk. Only opioid was thought to be effective. Then, intrathecal pump was considered. We estimated the minimal effective dose of spinal morphine before implantation. 0.3 mg of morphine was injected intrathecally as a starting dose. Dosage had been increased up to 0.8 mg in 10 days. His VAS score decreased from 8 to 5. He could sleep without pain and walk with crutch. Therefore, intrathecal pump was inserted. He could tolerate to pain. This case suggests that intrathecal morphine delivery can provide effective treatment for intractable non-malignant pain.

• 대한의용생체공학회:의공학회지
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• 제23권3호
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• pp.227-233
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• 2002

이식형 인공중이는 음질과 주파수 특성이 우수하며 기존의 공기전도형 보청기가 가지는 고이득에서의 왜곡과 음향 피이드백에 의한 링잉 현상을 해소할 수 있어 차세대 보청기로 주목받고 있다 특히 두 개의 영구자석을 같은 극기리 접착한 후 코일내부에 위치시킨 타동 전자 트랜스듀서 방식의 이식형 인공중이는 외부의 자기장에 대해 영향을 받지 않으며 진동효율이 높고 자석과 코일의 간격조정이 필요 없는 동시에 주파수 응답특성이 우수하다. 본 연구에서는 이식형 인공중이에 사용하위해 개발된 타동 전자 트랜스듀서의 음향 모델을 구현한 후 정상인의 귀의 청각 모델에 적용시켜 트랜스듀서를 통하여 내이로 전달되는 신호의 주파수 특성을 해석하였다. 해석된 결과를 정상인의 귀의 주파수 특성과 비교함으로써 인공중이를 사용할 경우와 정상인의 귀와의 신호전달 특성 차이를 조사하였고 이를 통하여 정상인의 청각특성에 가까운 신호를 전달시킬 수 있는 인공중이의 설계가 가능하도록 하였다.

• Archives of Plastic Surgery
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• 제44권1호
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• pp.34-41
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• 2017

Background The current indications of cardiac implantable electronic devices (CIEDs) have expanded to include young patients with serious cardiac risk factors, but CIED placement has the disadvantage of involving unsightly scarring and bulging of the chest wall. A collaborative team of cardiologists and plastic surgeons developed a technique for the subpectoral placement of CIEDs in young female patients via a transaxillary approach. Methods From July 2012 to December 2015, subpectoral CIED placement via an axillary incision was performed in 10 young female patients, with a mean age of 25.9 years and mean body mass index of $20.1kg/m^2$. In the supine position, with the patient's shoulder abducted, an approximately 5-cm linear incision was made along one of the deepest axillary creases. The submuscular plane was identified at the lateral border of the pectoralis major, and the dissection continued over the clavipectoral fascia until the subpectoral pocket could securely receive a pulse generator. Slight upward dissection also exposed an entrance to the subclavian vein, allowing the cardiology team to gain access to the vein. One patient with dilated cardiomyopathy underwent augmentation mammoplasty and CIED insertion simultaneously. Results One case of late-onset device infection occurred. All patients were highly satisfied with the results and reported that they would recommend the procedure to others. Conclusions With superior aesthetic outcomes compared to conventional methods, the subpectoral placement of CIEDs via a transaxillary approach is an effective, single-incision method to hide operative scarring and minimize bulging of the device, and is particularly beneficial for young female or lean patients.

• 센서학회지
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• 제1권2호
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• pp.147-154
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• 1992

본 논문은 생체 신호를 얻기 위한 생체삽입형 8-채널 바이오텔레메트리 시스템을 설계하였다. 본 시스템의 내부회로는 가능한 한 소형이고 저소비 전력화하였을 뿐만아니라 synchronization gap을 주기로 생채신호의 연속측정을 가능하도록 설계하였다. 본 시스템의 주된 기능은 생체신호 연속측정과 외부회로의 적절한 명령에 의해 생체 삽입 전지를 On, off하여 소비전력을 줄일 수 있도록 하였다. 또한 체내 삽입시스템을 집적화하기 위해 람다룰을 기본으로 한 $2{\mu}m$ n-well 설계규칙에 의해 레이아웃을 수행하였다. 그러므로 국내에서 개발되고 있는 압력센서나 ISFET 등을 본 시스템과 함께 삽입하여 생체신호, 즉 심전도, 혈류량, 혈압 등을 측정해 외부로 전송하는 의용 텔레메트리 시스템이 기대된다.

• 센서학회지
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• 제22권2호
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• pp.150-155
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• 2013

Recently, various hearing aids are developed to overcome hearing loss. There are available hearing aids, such as air conduction hearing aid, implantable middle ear hearing aid and so on. But air conduction hearing aid is inconvenience caused by howling, and ossicle chain driving type implantable middle ear hearing aid has some week point due to problem of possible nercobiosis of coupling spot along incus long process. In recent years, in order to improve these shortcomings round window (RW) driving hearing aid has been paying attention. In this paper, the physical cochlear model is proposed for a performance evaluation of the RW driving hearing aids of a transducer. In order to verify an experiment proposed on a performance of physical cochlear model, the transducer which has ossicles characteristics is used. By measuring and comparing the frequency characteristics of transducer with ossicles and human temporal bone, performance of physical cochlear model was verified. As from the result of experiment, it is expected that an implemented cochlear model is useful for evaluating characteristics of RW transducer.