Mr. Ashwin K. Whitchurch Profile

Ashwin K. Whitchurch

at Univ of Arkansas

SPIE Involvement:

Author

Publications (12)

Proceedings Article | 26 March 2008 Paper

Carbon nanotube strain sensors for wearable patient monitoring applications

Jose Abraham, Lavanya Aryasomayajula, Ashwin Whitchurch, Vijay Varadan

Proceedings Volume 6931, 69310J (2008) https://doi.org/10.1117/12.776181

KEYWORDS: Sensors, Carbon nanotubes, Composites, Nanocomposites, Vital signs, Prototyping, Algorithm development, Electronics, Scanning electron microscopy, Fiber optics sensors

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Proceedings Article | 26 March 2008 Paper

Low noise multi-channel biopotential wireless data acquisition system for dry electrodes

P. S Pandian, Ashwin Whitchurch, Jose Abraham, Himanshu Bhusan Baskey, J. K. Radhakrishnan, Vijay Varadan, V. C. Padaki, K. U. Bhasker Rao, R. Harbaugh

Proceedings Volume 6931, 69310Q (2008) https://doi.org/10.1117/12.798234

KEYWORDS: Electrodes, Skin, Electrocardiography, Signal processing, Amplifiers, Data acquisition, Electroencephalography, Electromyography, Resistance, Interference (communication)

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The bioelectrical potentials generated within the human body are the result of electrochemical activity in the excitable cells of the nervous, muscular or glandular tissues. The ionic potentials are measured using biopotential electrodes which convert ionic potentials to electronic potentials. The commonly monitored biopotential signals are Electrocardiogram (ECG), Electroencephalogram (EEG) and Electromyogram (EMG). The electrodes used to monitor biopotential signals are Ag-AgCl and gold, which require skin preparation by means of scrubbing to remove the dead cells and application of electrolytic gel to reduce the skin contact resistance. The gels used in biopotential recordings dry out when used for longer durations and add noise to the signals and also prolonged use of gels cause irritations and rashes to skin. Also noises such as motion artifact and baseline wander are added to the biopotential signals as the electrode floats over the electrolytic gel during monitoring. To overcome these drawbacks, dry electrodes are used, where the electrodes are held against the skin surface to establish contact with the skin without the need for electrolytic fluids or gels. The major drawback associated with the dry electrodes is the high skin-electrode impedance in the low frequency range between 0.1-120 Hz, which makes it difficult to acquire clean and noise free biopotential signals. The paper presents the design and development of biopotential data acquisition and processing system to acquire biopotential signals from dry electrodes. The electrode-skin-electrode- impedance (ESEI) measurements was carried out for the dry electrodes by impedance spectroscopy. The biopotential signals are processed using an instrumentation amplifier with high CMRR and high input impedance achieved by boot strapping the input terminals. The signals are band limited by means of a second order Butterworth band pass filters to eliminate noise. The processed biopotential signals are digitized and transmitted wirelessly to a remote monitoring station.

Proceedings Article | 11 April 2007 Paper

A total patient monitoring system for point-of-care applications

Ashwin Whitchurch, Jose Abraham, Vijay Varadan

Proceedings Volume 6528, 65280R (2007) https://doi.org/10.1117/12.717664

KEYWORDS: Sensors, Electroencephalography, Electrocardiography, Telecommunications, Analog electronics, Internet, Vital signs, Point-of-care devices, Medicine, Receivers

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Proceedings Article | 31 March 2006 Paper

Neuroelectronics and neurosurgery

Ashwin Whitchurch, Vijay Varadan

Proceedings Volume 6172, 61720S (2006) https://doi.org/10.1117/12.668749

KEYWORDS: Neurons, Brain, Electroencephalography, Electrodes, Nerve, Electronics, Interfaces, Ions, Epilepsy, Carbon nanotubes

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Proceedings Article | 16 May 2005 Paper

Wireless microsensor network solutions for neurological implantable devices

Jose Abraham, Ashwin Whitchurch, Vijay Varadan

Proceedings Volume 5763, (2005) https://doi.org/10.1117/12.608124

KEYWORDS: Sensors, Electrodes, Brain, Antennas, Telecommunications, Control systems, Electroencephalography, Epilepsy, Microsensors, Microcontrollers

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The design and development of wireless mocrosensor network systems for the treatment of many degenerative as well as traumatic neurological disorders is presented in this paper. Due to the advances in micro and nano sensors and wireless systems, the biomedical sensors have the potential to revolutionize many areas in healthcare systems. The integration of nanodevices with neurons that are in communication with smart microsensor systems has great potential in the treatment of many neurodegenerative brain disorders. It is well established that patients suffering from either Parkinson’s disease (PD) or Epilepsy have benefited from the advantages of implantable devices in the neural pathways of the brain to alter the undesired signals thus restoring proper function. In addition, implantable devices have successfully blocked pain signals and controlled various pelvic muscles in patients with urinary and fecal incontinence. Even though the existing technology has made a tremendous impact on controlling the deleterious effects of disease, it is still in its infancy. This paper presents solutions of many problems of today's implantable and neural-electronic interface devices by combining nanowires and microelectronics with BioMEMS and applying them at cellular level for the development of a total wireless feedback control system. The only device that will actually be implanted in this research is the electrodes. All necessary controllers will be housed in accessories that are outside the body that communicate with the implanted electrodes through tiny inductively-coupled antennas. A Parkinson disease patient can just wear a hat-system close to the implantable neural probe so that the patient is free to move around, while the sensors continually monitor, record, transmit all vital information to health care specialist. In the event of a problem, the system provides an early warning to the patient while they are still mobile thus providing them the opportunity to react and trigger the feed back system or contact a point-of-care office that can remotely control the implantable system. The remote monitoring technology can be adaptable to EEG monitoring of children with epilepsy, implantable cardioverters/defibrillators, pacemakers, chronic pain management systems, treatment for sleep disorders, patients with implantable devices for diabetes. In addition, the development of a wireless neural electronics interface to detect, transmit and analyze neural signals could help patients with spinal injuries to regain some semblance of mobile activity.

Proceedings Article | 22 July 2003 Paper

Microsensors and wireless system for monitoring epilepsy

Ashwin Whitchurch, B. Ashok, Raman Kumaar, K. Sarukesi, K. Jose, Vijay Varadan

Proceedings Volume 5055, (2003) https://doi.org/10.1117/12.497443

KEYWORDS: Epilepsy, Electroencephalography, Electrodes, Brain, Amplifiers, Microcontrollers, Microsensors, Computing systems, Neurons, Visualization

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Proceedings Article | 22 July 2003 Paper

Noninvasive biosensor and wireless interrogating system for glucose in blood

Vijay Varadan, Ashwin Whitchurch, K. Sarukesi

Proceedings Volume 5055, (2003) https://doi.org/10.1117/12.497445

KEYWORDS: Glucose, Blood, Sensors, Skin, Tissues, Molecules, Light emitting diodes, Temperature metrology, Calibration, Polarimetry

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Proceedings Article | 22 July 2003 Paper

Wireless tuning fork gyroscope for biomedical applications

Jose Abraham, Vijay Varadan, Ashwin Whitchurch, K. Sarukesi

Proceedings Volume 5055, (2003) https://doi.org/10.1117/12.497455

KEYWORDS: Sensors, Gyroscopes, Biomedical optics, Telecommunications, Human-computer interaction, Tuning fork gyroscopes, Sensing systems, Reliability, Microelectromechanical systems, Analog electronics

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Proceedings Article | 18 April 2003 Paper

Wireless patient monitoring on shoe for the assessment of foot dysfunction: an overview

Jose Abraham, Ashwin Whitchurch, Vijay Varadan, Karunakaran Sarukesi

Proceedings Volume 5119, (2003) https://doi.org/10.1117/12.499186

KEYWORDS: Gyroscopes, Sensors, Human-machine interfaces, Computing systems, Microcontrollers, Sensing systems, Analog electronics, Tissues, Injuries, Signal detection

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