SADIK KARA
Fatih University, Institute of Biomedical Engineering, Faculty Member
- Sadık Kara was born in Kayseri in 1959. He completed his primary and high school education in Kayseri. He was graduat... moreSadık Kara was born in Kayseri in 1959. He completed his primary and high school education in Kayseri. He was graduated from Department of Electronics Engineering at Erciyes University in 1988. He had work experiences at various companies such as Turkish Electricity Association, Birlik Mensucat Textile Factory, and Military 2nd Maintenance Centre as an engineer. His academic career was started at Erciyes University in 1991 as a Teaching and Research Assistant. In 1995, he became Assistant Professor at Department of Electronics Engineering. In 2000, he received his Assoc. Prof. Degree on Bio-electronics. He is married and has 3 children.
He has also interested in music besides his academic studies. His amateur music life started in 1970s. On those days, he had learned to play “OUD” from his father. His tendency for playing Ud has growing and growing with great love. This worship brought about good companions in academic and musical societies. He has given many concerts and recitals. His studies were published in various national and international journals.
He had worked in Turkish Journal of Electrical Engineering & Computer Sciences as an Editor in Chief from 2009 to 2014 and has been working as a Professor at Fatih University as well as the Director of the Institute of Biomedical Engineering and Head of Conservatory since 2008.edit
Closed rectum is a very frequently encountered anomaly of the newborns in our university hospital. Before making a rectal opening, the anorectal sphincter muscle needs to be stimulated to prevent any damage to the muscle itself. In this... more
Closed rectum is a very frequently encountered anomaly of the newborns in our university hospital. Before making a rectal opening, the anorectal sphincter muscle needs to be stimulated to prevent any damage to the muscle itself. In this study, we have designed a stimulator that provides reasonably constant output current depending on the physiological impedance of the rectal area. The current amplitude can be set between 20 and 250 mA. Stimulation pulses are adjusted for duration of 230 µs and can be obtained at a repetition period between 1.75 and 20 ms. Fifteen patients in the Pediatric Surgery Department of Erciyes University Hospital were subjected to our stimulation tests. On average, about 140 mA was enough to stimulate the muscle when probes were applied over the skin. On the other hand, with the placement of probes beneath the skin, stimulation was obtained for pulse amplitude of 40 mA.
Research Interests:
Mechanical heart valves are a substitute for malfunctional native heart valves. In this study, the spectral features of S1 and S2 component of the mechanical heart valve sounds obtained after aortic valve replacement (AVR) and mitral... more
Mechanical heart valves are a substitute for malfunctional native heart valves. In this study, the spectral features of S1 and S2 component of the mechanical heart valve sounds obtained after aortic valve replacement (AVR) and mitral valve replacement (MVR) are compared. For this aim, AR methods are applied on the S1 and S2 components of heart sounds taken from 68 recording of 8 patients with AVR and 87 recordings from 11 patients with MVR, thereby yielding power spectrum of the heart sound and six different features are obtained from power spectrum of the heart sounds. Using these features, S1 and S2 components are compared.
Research Interests:
Doppler signals from the umbilical artery of 20 women with normal pregnancy between 18 and 20 weeks of gestation were recorded. The AR spectral analysis method has been used to obtain the Doppler sonograms of umbilical artery belonging to... more
Doppler signals from the umbilical artery of 20 women with normal pregnancy between 18 and 20 weeks of gestation were recorded. The AR spectral analysis method has been used to obtain the Doppler sonograms of umbilical artery belonging to normal pregnant subjects and fractal dimension curves were calculated using Hurst exponent. RI; PI and S/D indexes have been calculated from the maximum frequency envelope of Doppler sono-grams and from the fractal dimension curve. Area under the curve from ROC curve for RI, PI and S/D indexes derived from maximum frequency waveform were calculated as 0.931, 0.959, 0.938, respectively and area under the curve for RI, PI and S/D indexes derived from fractal dimension curve were calculated as 0.933, 0.961, and 0.941, respectively. These results show that, the Doppler indexes derived from fractal dimension curve are as sensitive as Doppler indexes derived from maximum velocity curve. Power Spectral Density graphics were derived from Doppler signals and Hurst exponent values calculated to evaluate the blood flow changing during pregnancy. ROC curve for PSD HURST index was calculated as 0.97. According to this result, PSD HURST index is more sensitive to detect the blood flow changing than traditional Doppler indexes.
The acquired 72 normal sinus rhythm ECGs and 80 ECGs with atrial fibrillation (AF) are decomposed with 'db10' Daebauchies wavelets at level 6 and power spectral density was calculated for each decomposed signal with Welch method. Average... more
The acquired 72 normal sinus rhythm ECGs and 80 ECGs with atrial fibrillation (AF) are decomposed with 'db10' Daebauchies wavelets at level 6 and power spectral density was calculated for each decomposed signal with Welch method. Average power spectral density was calculated for six subbands and normalized to be used as input to the neural network. Levenberg–Marquart backpropagation feed forward neural network was built from logarithmic sigmoid transfer functions in three-layer form. The trained network was tested on 24 normal and 28 AF state ECGs. The classification performance was accomplished as 100% accurate.
In this study, we developed an expert diagnostic system for the interpretation of the portal vein Doppler signals belong the patients with cirrhosis and healthy subjects using signal processing and Artificial Neural Network (ANN) methods.... more
In this study, we developed an expert diagnostic system for the interpretation of the portal vein Doppler signals belong the patients with cirrhosis and healthy subjects using signal processing and Artificial Neural Network (ANN) methods. Power spectral densities (PSD) of these signals were obtained to input of ANN using Short Time Fourier Transform (STFT) method. The four layered Multilayer Perceptron (MLP) training algorithms that we have built had given very promising results in classifying the healthy and cirrhosis. For prediction purposes, it has been presented that Levenberg Marquardt training algorithm of MLP network employing backpropagation works reasonably well. The diagnosis performance of the study shows the advantages of this system: It is rapid, easy to operate, noninvasive and not expensive. This system is of the better clinical application over others, especially for earlier survey of population. The stated results show that the proposed method can make an effective interpretation and point out the ability of design of a new intelligent assistance diagnosis system.
This research is concentrated on the diagnosis of subnormal eye through the analysis of Electrooculography (EOG) signals with the help of Artificial Neural Network (ANN). Multilayer feed forward ANN trained with a Levenberg Marquart (LM)... more
This research is concentrated on the diagnosis of subnormal eye through the analysis of Electrooculography (EOG) signals with the help of Artificial Neural Network (ANN). Multilayer feed forward ANN trained with a Levenberg Marquart (LM) backpropagation algorithm was implemented. The designed classification structure has about 94.1% sensitivity, 93.3% specifity and positive prediction is calculated to be 94.1%. The end results are classified as normal and subnormal eye. Testing results were found to be compliant with the expected results that are derived from the physician's direct diagnosis. The benefit of the system is to assist the physician to make the final decision without hesitation. With the future evolution of this system tested on a more populated subject groups, there is always potential for on-line implementation as an auxiliary diagnostic tool on the Electrophysiology machines.
In this paper, we purpose a diagnostic procedure to identify the macular disease from pattern electroretionography (PERG) signals using artificial neural networks (ANN) methods. Multilayer feed forward ANN trained with a Levenberg... more
In this paper, we purpose a diagnostic procedure to identify the macular disease from pattern electroretionography (PERG) signals using artificial neural networks (ANN) methods. Multilayer feed forward ANN trained with a Levenberg Marquart backpropagation algorithm was implemented. The designed classification structure has about 96% sensitivity, 100% specifity and correct classification is calculated to be 98%. The end results are classified as Healthy and Diseased. Testing results were found to be compliant with the expected results that are derived from the physician's direct diagnosis, angiography and Arden ratio of electrooculogram (EOG). The stated results show that the proposed method could point out the ability of design of a new intelligent assistance diagnosis system.
In this study, we have produced discontinuous Doppler signals of carotid artery and internal jugular vein, simulating respiratory misregistration. The aim of the study is to observe the effect of signal discontinuity and its duration on... more
In this study, we have produced discontinuous Doppler signals of carotid artery and internal jugular vein, simulating respiratory misregistration. The aim of the study is to observe the effect of signal discontinuity and its duration on power spectral density vs. frequency graphs obtained by Autoregressive Modeling. The signals were recorded from ten male volunteers. Signal interruption was performed by moving the sampling volume in and out of the vessel bidirectionally. To estimate the effect of on-line recording time and signal discontinuity on frequency spectra, we have worked on a control data of 30 s with continuous signal, and three sets of data with artificially interrupted signals of 30, 60 and 90 s duration. Maximum power spectral density, area under the power spectral density, and frequency level corresponding to maximum power spectral density were calculated on frequency spectra. The frequency level corresponding to maximum power spectral density provides the most statistically stable finding in our preliminary data. The signal duration of the signal had no significant effect on the statistical stability of the frequency level.
Atherosclerosis means thickening and hardening of the arteries, which has dramatic effects on blood pressure, resistance and blood flow. Since angiography is invasive and has a relatively high cost, non-invasive ultrasonic Doppler... more
Atherosclerosis means thickening and hardening of the arteries, which has dramatic effects on blood pressure, resistance and blood flow. Since angiography is invasive and has a relatively high cost, non-invasive ultrasonic Doppler sonography is generally recommended to diagnose of athersosclerosis. In this study, we have employed the sonograms depicted from Autoregressive (AR) modeling, Principles component analysis (PCA) for data reduction of Doppler sonograms and artificial neural networks (ANN) in order to distinguish between atherosclerosis and healthy subjects. The fuzzy appearance of the carotid artery Doppler signals makes physicians suspicious about the existence of diseases and causes false diagnosis. Our technique gets around this problem using ANN to decide and assist the physician to make the final judgment in confidence. The stated results show that training time and processing complexity were reduced using PCA-ANN architecture however the proposed method can make an effective interpretation and ANN classified Doppler signals successfully.
Till today, many different ECG devices are made in developing countries. In this study, low cost, small size, portable LCD screen ECG device, and phonocardiograph were designed. With designed system, heart sounds that take synchronously... more
Till today, many different ECG devices are made in developing countries. In this study, low cost, small size, portable LCD screen ECG device, and phonocardiograph were designed. With designed system, heart sounds that take synchronously with ECG signal are heard as sensitive. Improved system consist three units; Unit 1, ECG circuit, filter and amplifier structure. Unit 2, heart sound acquisition circuit. Unit 3, microcontroller, graphic LCD and ECG signal sending unit to computer. Our system can be used easily in different departments of the hospital, health institution and clinics, village clinic and also in houses because of its small size structure and other benefits. In this way, it is possible that to see ECG signal and hear heart sounds as synchronously and sensitively. In conclusion, heart sounds are heard on the part of both doctor and patient because sounds are given to environment with a tiny speaker. Thus, the patient knows and hears heart sounds him/herself and is acquainted by doctor about healthy condition.
Digital imaging of cancerous cells is instrumental not only in determining the characteristic of the cancer but also monitoring the progress of the disease in the follow up of the patient and adapting the treatment, accordingly.... more
Digital imaging of cancerous cells is instrumental not only in determining the characteristic of the cancer but also monitoring the progress of the disease in the follow up of the patient and adapting the treatment, accordingly. Therefore, we have developed an imaging system to display and layout the characteristics of normal and cancer-ous cells in an automated way. Image processing techniques are performed on the digitized images of stomach and skin tissues, in order to derive the number of cells, area of an individual cell, and average area of the cells in a certain size of an image window.
Digital imaging of cancerous cells is instrumental not only in determining the characteristic of the cancer but also monitoring the progress of the disease in the follow up of the patient and adapting the treatment, accordingly.... more
Digital imaging of cancerous cells is instrumental not only in determining the characteristic of the cancer but also monitoring the progress of the disease in the follow up of the patient and adapting the treatment, accordingly. Therefore, we have developed an imaging system to display and layout the characteristics of normal and cancer-ous cells in an automated way. Image processing techniques are performed on the digitized images of stomach and skin tissues, in order to derive the number of cells, area of an individual cell, and average area of the cells in a certain size of an image window.
In this study, we have performed fast Fourier transformation (FFT) and autoregressive (AR) signal processing of the Doppler signals at a nonstenotic arterial site in patients with atherosclerosis and healthy volunteers. We have not only... more
In this study, we have performed fast Fourier transformation (FFT) and autoregressive (AR) signal processing of the Doppler signals at a nonstenotic arterial site in patients with atherosclerosis and healthy volunteers. We have not only utilized Doppler sonograms, but also facilitated the power spectral density distribution graphs using AR modeling and FFT. Our preliminary analysis show that AR modeling has a higher eecacy in demonstrating Doppler spectral waveform changes in the preclinic or silent phase of atherosclerosis. AR has especially revealed an outstanding diierence in the calculation for frequency level of maximum power spectral density.
Facial nerves are very prone to risk of being cut away in the facial surgeries. In order to differentiate the normal tissues from the nerves during the surgeries, facial stimulator is very essential. These stimulators are particularly... more
Facial nerves are very prone to risk of being cut away in the facial surgeries. In order to differentiate the normal tissues from the nerves during the surgeries, facial stimulator is very essential. These stimulators are particularly useful in triggering action potentials in the facial muscle tissue. In the case of any damage to these nerves, paralysis is unavoidable. Second use of the stimulator would be to diagnose how severe the facial problems are. Third use, which is a noninvasive application, is the employment of facial stimulator to treat and diagnose facial problems that arose from temperature differences, cuts or strain. The stimulation is achieved through DC voltage pulses that conform to user-specified amplitude, pulse duration and pulse intervals. These variables are set according to the age, sex, and physiological conditions of the patient. Peripheral Interface Controller is used to derive different pulse patterns. The current specifications of our stimulator are a range of 0.1–20 V pulse amplitude, 0.1– 2 msec pulse duration, and 0.05–1 sec pulse interval. The main benefits of our stim-ulator are its graphic display that shows the form of pulse, its compact size, and operation on a battery power supply and adaptability to convert to other stimulation applications.
First derivative of arterial blood pressure, dp/dt is known to reflect the contractility power of the heart. We hypothesize that the calculated area under each cardiac cycle of the blood pressure curve is also another practical tool in... more
First derivative of arterial blood pressure, dp/dt is known to reflect the contractility power of the heart. We hypothesize that the calculated area under each cardiac cycle of the blood pressure curve is also another practical tool in revealing the heart contractility power. Of the 84 subjects, 61 patients were found to have adequate contractility power (high dp/dt) and their mean area calculation resulted in 64.2 mmHg s with a standard deviation of 2.9 mmHg s. The remaining 23 patients have indicated poor heart contractility power (low dp/dt) and stayed in serious condition for long time. This group had mean area of 41.4 ± 3.1 mmHg s. Patients with poor contractility power had areas below 45 mmHg s, while all area calculations for patients with high contractility power stayed over 60 mmHg s. Therefore, small area of the arterial blood pressure curves seems to be a good indicator of a poor heart contractility power and the area calculation may be an adjunct parameter to the dp/dt that has been employed for the assessment of heart contractility.
Closed rectum is a very frequently encountered anomaly of the newborns in our university hospital. Before making a rectal opening, the anorectal sphincter muscle needs to be stimulated to prevent any damage to the muscle itself. In this... more
Closed rectum is a very frequently encountered anomaly of the newborns in our university hospital. Before making a rectal opening, the anorectal sphincter muscle needs to be stimulated to prevent any damage to the muscle itself. In this study, we have designed a stimulator that provides reasonably constant output current depending on the physiological impedance of the rectal area. The current amplitude can be set between 20 and 250 mA. Stimulation pulses are adjusted for duration of 230 µs and can be obtained at a repetition period between 1.75 and 20 ms. Fifteen patients in the Pediatric Surgery Department of Erciyes University Hospital were subjected to our stimulation tests. On average, about 140 mA was enough to stimulate the muscle when probes were applied over the skin. On the other hand, with the placement of probes beneath the skin, stimulation was obtained for pulse amplitude of 40 mA.
In Hirschsprung's disease, the internal anorectal sphincter fails to relax in response to rectal distension, which strongly indicates the absence of rectoanal inhibitory reflex (RAIR). Hirschsprung's disease is a very common case... more
In Hirschsprung's disease, the internal anorectal sphincter fails to relax in response to rectal distension, which strongly indicates the absence of rectoanal inhibitory reflex (RAIR). Hirschsprung's disease is a very common case particularly encountered in the newborns in our region. Development of a manometric system targeted specifically for the diagnosis of this disease at a reasonable cost is an urgent need identified by our regional colorectal surgeons. These surgeons indicated that commercially available anorectal manometers are too expensive to acquire. Therefore, in our research we tried to develop a low-cost single balloon-transducer system, which only provides information about RAIR, and hence diagnoses the Hirschsprung's disease. The hardware part of our instrumentation is made of a latex balloon, pressure transducer , amplifier, and A/D converter circuits, which all collects the pressure readings and sends the data to the computer. The manometer system software, programmed based on Delphi, displays these readings and patient information on a computer screen. This designed system was successful enough to perform manometric recording of RAIR in the anorectal ampulla of rabbits and rats.
Özet: Bu çalışmada kalp seslerinin EKG işaretleri ile birlikte eşzamanlı olarak alınması için bir enstrümantasyon sistemi tasarlanmıştır. Donanımın amacı kalp kapağı fonksiyonsuzluğu olan hastalardan kalbe ait ses ve EKG bilgilerinin... more
Özet: Bu çalışmada kalp seslerinin EKG işaretleri ile birlikte eşzamanlı olarak alınması için bir enstrümantasyon sistemi tasarlanmıştır. Donanımın amacı kalp kapağı fonksiyonsuzluğu olan hastalardan kalbe ait ses ve EKG bilgilerinin alınarak bilgisayara aktarılması ve görüntülenmesini sağlamaktır. Kalp seslerinin alınabilmesi için ortamdan yalıtılmış kapasitif bir dönüştürücü kullanılmıştır. EKG işaretleri ise yüzey elektrotları ile alınmıştır. Her iki işaret de ayrı ayrı kuvvetlendirme ve filtreleme bölümlerinden geçirilmiştir. Elde edilen kalp sesi ve EKG bilgileri tasarlanan bir Giriş/Çıkış kartı aracılığıyla sayısal forma dönüştürülerek bilgisayara aktarılmaktadır. Ayrıca elde edilen ses, EKG ve hastaya ait çeşitli bilgilerin görüntülenebilmesi, işlenebilmesi ve kaydedilebilmesi için Delphi programında yazılmış bir yazılım oluşturulmuştur. Yapılan bu çalışmayla hasta ses bilgilerinin dinlenerek değil, görsel olarak değerlendirilmesine imkan sağlanmıştır. Abstract: In this study, it was designed the instrumentation system which provided image of heart sounds synchronous ECG signals. Purpose of this system hardware has been provided to monitorize and transfer to computer of heart sounds and ECG signals acquired with from patients heart valve dysfunctions. The capacitive transducer insulated from its surrounding has been used in order to take heart sounds. ECG signals have been taken by surface electrode. ECG signals and heart sounds have been amplificated and filtered separately. In following process, these signals have been transferred to computer by converting digital form via designed I/O card. Also, the software in Delphi packet has been formed in order to record, processing and monitorize to the sounds, ECG signals and various information belong to patients. In this way, the stored sound data have been demonstrated in graphics mode as alternative method instead of heart sounds listening method.
Research Interests: Information Systems, Electroencephalography, Humans, Female, Male, and 10 moreMedical systems, Differential Diagnosis, Singular Spectrum Analysis, Middle Aged, Adult, Public health systems and services research, Singular-spectrum Analysis, Sensitivity and Specificity, Artificial Neural Network, and Sleep Stages
Research Interests:
In this study, normal EEG series recorded from healthy volunteers and epileptic EEG series recorded from patients within and without seizure are classified by using Multilayer Neural Network (MLNN) architectures with respect to several... more
In this study, normal EEG series recorded from healthy volunteers and epileptic EEG series recorded from patients within and without seizure are classified by using Multilayer Neural Network (MLNN) architectures with respect to several time domain entropy measures such as Shannon Entropy (ShanEn), Log Energy Entropy (LogEn), and Sample Entropy (Sampen). In tests, the MLNN is performed with several numbers of neurons for both one hidden layer and two hidden layers. The results show that segments in seizure have significantly lower entropy values than normal EEG series. This result indicates an important increase of EEG regularity in epilepsy patients. The LogEn approach, which has not been experienced in EEG classification yet, provides the most reliable features into the EEG classification with very low absolute error as 0.01. In particular, the MLNN can be proposed to distinguish the seizure activity from the seizure-free epileptic series where the LogEn values are considered as si...
Research Interests:
Özetçe Üst ekstremitenin tekrarlı hareketlerinin aşırı kullanım yaralanmalarına yol açtığı bilinmektedir fakat buna neden olan hareketleri ayırt etmek oldukça zordur. Bu çalışmanın birincil amacı sağlıklı bireylerde farklı omuz... more
Özetçe Üst ekstremitenin tekrarlı hareketlerinin aşırı kullanım yaralanmalarına yol açtığı bilinmektedir fakat buna neden olan hareketleri ayırt etmek oldukça zordur. Bu çalışmanın birincil amacı sağlıklı bireylerde farklı omuz pozisyonlarının kavrama kuvvetine ve üst ekstremite kaslarının elektro fizyolojik aktivitesi üzerine etkisini belirlemektir. Sağlıklı populasyondan yaşları 18-30 arası olan 23 olgunun verileri analiz edildi. Sonuçlarımıza göre omuz fleksiyonu arttıkça kas aktivitesi ve buna bağlı muhtemel kas yorgunluğu artarken el fonksiyonelliği azaltmaktaydı. Bu durum hem mesleki hastalık bakımından risk hem de fonksiyonun verimli kullanılırlığını azaltan bir durumdur. İleriki çalışmalarda omuz üstü çalışma gerektiren durumlarda kullanılabilecek yorgunluk azaltıcı aparatlar ve sistemlerin faydalarının EMG analizleri ile incelenmesi tavsiye edilmektedir. Anahtar Kelimeler : Ergonomi, elektromyografi, kas iskelet sistemi hastalığı, omuz üstü çalışma, sinyal işleme Abstract It is known that repeated movements of upper extremities result in over use injuries however, it is really challenging to distinguish which of them do so. Primary aim of the project is to determine the effect of different shoulder positions on gripping capability of hand and electro physiologic activityof upper extremity muscles. 23 case report data which have ages ranging between 18 and 30 are analysed. Depending on the shoulder flexion, hand gripping capability decreased explicitly. Suggested to analyse together with the fact that at levels higher than shoulders, despite maximum muscular activitythe hand gripping capability decreased explicitly is interpreted so that when the arm is raised the extremity exerts higher efforts for stabilizing the arm rather than ripping function. According to our results, as the shoulder flexion increases, muscular activity and depending on this the muscular exhaustion also increases where as the functional quality of hand decreases. The case is both a risk factor for an occupational disease and a situation that decreases skillful functioning of hands. For the next researches, advantages of exhaustion reducing apparatus and ergonomic systems, which can be used during works requiring over shoulder movements, are EMG results.
Research Interests:
— Repeated movements of upper extremities cause to overuse injuries however, it is really challenging to determine which of them do so. Primary aim of the project is to determine the effect of different shoulder positions on gripping... more
— Repeated movements of upper extremities cause to overuse injuries however, it is really challenging to determine which of them do so. Primary aim of the project is to determine the effect of different shoulder positions on gripping capability of hand and electro physiologic activity of upper extremity muscles. 23 case report data which have ages ranging between 18 and 30 are analyzed. According to our results, as the shoulder flexion increases, muscular activity and depending on this the muscular exhaustion also increases whereas the functional quality of hand decreases. The case is both a risk factor for an occupational disease and a situation that decreases skillful functioning of hands. For the next researches, advantages of exhaustion reducing apparatus and ergonomic systems, which can be used during works requiring over shoulder movements, are EMG results.