Thomas E. Doyle

Design of an Electroocular Computing Interface

The human retina consists of an electrically-charged nerve membrane. This potential is a constant value for a given adaptation without stimulation; it is the retinal resting potential. The retinal resting potential causes an electric field around the eyeball, centered on the optical axis, which can be measured by placing electrodes near to the eye. As a result, the motion of the eye causes a measurable change of DC voltage between the surface electrodes. The same vector coordinate system employed in the modern computer mouse may be adapted for use with our electro-ocular interface. Such a device would provide a relative position of gaze and have application in both hands-busy and assistive research. The theory behind our device, hardware design, the experimental results, and efficacy of the system are presented

Data acquisition system for the measurements of corona currents

The measurements of voltage-current relationships in gas discharge systems often require special equipment not readily available on the market. In the presented study, a data requisition system is described, which was used for the measurements of corona currents in a pin-plane corona generator of the array type, with pins negative. The pins were made of tungsten and were arranged in two rows. The ground plane was planar, made of aluminum, and equipped with circular current-sensing electrodes made of brass and insulated from the planar anode with teflon rings. Each of the sensing electrodes was connected to 50 k/spl Omega/ resistor. The voltage across each of the resistors was measured with an operational amplifier circuit. The output of the operational amplifier was connected to an electronic scanner, the output of which was used as the input for a microcontroller (HC11, Motorola). The microcontroller was connected via the RS 232 link to an interfacing board inserted into the PCI bus of a personal computer. The computer provided a graphical user interface was used to store and process the collected data, and supported the popular data processing programs. The system allowed the measurements of the current magnitudes on up to sixteen corona pin, simultaneously. The computer interfacing board can parse the data into up to eight separate data streams. The data acquisition unit can be configured to operate with four, eight, or sixteen input channels, trading their number for the sampling rate and frequency response in three steps: 4 channels, 16,000 samples.s/sup -1/; 8 kHz; 8 channels, 8,000 samples.s/sup -1/, 4 kHz; 16 channels, 4,000 samples.s/sup -1/, 2 kHz. In the described experiment, the system was set to sample four simultaneous data streams and provided adequate response. The system operated at the same ground level as the high voltage ground. The cost of the parts used in the unit is approximately fifty dollars. With an appropriate set of sensors, the unit can be used in other high voltage applications.

M4CVD: Mobile Machine Learning Model for Monitoring Cardiovascular Disease

Abstract In this paper we present M4CVD: Mobile Machine Learning Model for Monitoring Cardiovascular Disease, a system designed specifically for mobile devices that facilitates monitoring of cardiovascular disease (CVD). The system uses wearable sensors to collect observable trends of vital signs contextualized with data from clinical databases. Instead of transferring the raw data directly to the health care professionals, the system performs analysis on the local device by feeding the hybrid of collected data to a support vector machine (SVM) to monitor features extracted from clinical databases and wearable sensors to classify a patient as “continued risk” or “no longer at risk” for CVD. As a work in progress we evaluate a proof-of-concept M4CVD using a synthetic clinical database of 200 patients. The results of our experiment show the system was successful in classifying a patients CVD risk with an accuracy of 90.5%.

Comparative Electrochemical Investigation of Pt, Au and Ti Electrodes on Liquid Crystal Polymer for the Application of Neuromuscular Prostheses

This paper studies the electrochemical impedance of Platinum (Pt), Gold (Au), and Titanium (Ti) deposited on liquid crystal polymer (LCP) to understand charge transfer mechanism of implantable electrodes for neuromuscular electrical stimulation. Electrodes are fabricated through e-beam evaporation and characterized using electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM) measurements. A theoretical model is proposed to explain physical functionalities. The results demonstrate as the size of electrodes increases, higher conductivity and double layer capacitance are obtained. In neuromuscular stimulation frequencies, Pt electrodes offer the best conductivity followed by Ti and Au respectively. This material dependence of impedance magnitude is related to the surface morphology of the electrodes and is assessed by AFM. Deposition pressure dependence of Ti electrodes on the impedance is observed due to change of surface roughness and double layer capacitor. This study addresses the interface impedance of implanted electrodes and permits further development of neuromuscular prostheses.

Scaling Law for Electrospray Droplet Formation

There has been a lot of research on liquid atomization by means of electrospray, particularly because of its many practical applications. Nevertheless, full understanding and control of the electrospray mechanisms are still incomplete. An experimental setup was developed in order to investigate the frequency characteristics of droplet formation and ejection at the tip of Taylors cone of aqueous electrosprays. Droplet formation and oscillations were monitored using a Kodak Ektapro high-speed camera. The frequency of droplet formation at the tip of the capillary needle was analyzed. Droplet frequency formation appears to exhibit three distinct regimes with an abrupt transition from one regime to another. Droplet formation was recorded at different needle-plate electrode distances. Based on the analysis of experimental data a scaling law for droplet formation was found.

Affective State Control for Neuroprostheses

The control and communication in man and the machine has been an active area of research since the early 1940s and since then the usage of the computing machine for the enhancement, augmentation, and rehabilitation of mankind has been broadly investigated. One active area of such research is the interface of the human brain to the computer; brain-computer-interfacing (BCI) or neuroprostheses. Current examples of functional BCI typically control the computer screen cursor movement, but require extensive subject training and significant, if not full, cognitive focus. Our model proposed an alternative approach to implementing the BCI for the application of controlling a digital hearing aid by autonomously modifying the speech signal based on the identification of electrophysiological response, or an affective state. Using a support vector machine binary classifier our model successfully demonstrated the efficacy of single-trial identification of affective states as an enhanced method of hearing neuroprosthetic control at a communication transfer rate of 240 bits/minute

Onset Characteristics of Aqueous Large Gap Electrosprays

Electrosprays (ESs) have a wide variety of applications. In particular, the onset voltage parameter is of special interest. Our study investigated onset characteristics of aqueous ESs in a negative polarity for capillary tip-plate distances in the range of 0.5-50 cm. Experiments show significant variation of onset voltage with the presence of metal objects in the proximity of the ES. Data analysis shows an increase in onset voltage with the decrease in counterelectrode radius. The region least sensitive to such variation was found for tip-plate distances larger than 20 cm. Onset voltages appear to be in agreement with Smiths formula for a certain range of the distance studied. Gaps larger than 25 cm have generally shown more significant variations of this formula. The results of the present study can be useful for the design of ESs of larger gaps.

Optical decoupling in measurements of corona currents

The paper deals with the measurements of the corona parameters in a linear eight-electrode pin-to-plane array generator. The pins were made of tungsten, arranged in one row of eight, and were biased negative. The ground plane was flat, made of aluminum, and incorporated brass current-sensing electrodes, insulated from the anode. The anode was grounded, and each of the sensing electrodes was connected to an operational amplifier based current-to-voltage converter with sensitivity of R=1V/spl middot//spl mu/A/sup -1/. The output of each of the converters was connected to a scanner and a microcontroller, which was supported by a personal computer, that provided graphical user interface, data storage, and the RS232C link needed to communicate with the microcontroller. Corona current was measured simultaneously on the eight corona pins; at the same time the value of the voltage applied to the generator and the total current supplied to the array were measured. The measurement of the total current was performed by a transmitter module, floating at a voltage of up to 30 kV, decoupled from the rest of the system by an optical fiber link. The data acquisition apparatus could be configured to operate with four, eight, or sixteen input channels, trading the number of inputs for the sampling rate and frequency response in three steps: 4 channels, 16000 samples.s/sup -1/, 8 kHz; 8 channels, 8000 samples.s/sup -1/, 4 kHz; 16 channels, 4000 samples.s/sup -1/, 2 kHz bandwidth.

A social cybernetic analysis of simulation-based, remotely delivered medical skills training in an austere environment: Developing a test bed for spaceflight medicine

This paper describes analysis of medical skills training exercises that were conducted at an arctic research station. These were conducted as part of an ongoing effort to establish high fidelity medical simulation test bed capabilities in remote and extreme “space analogue” environments for the purpose studying medical care in spaceflight. The methodological orientation followed by the authors is that of “second order cybernetics,” or the science of studying human systems where the observer is involved within the system in question. Analyses presented include the identification of three distinct phases of the training activity, and two distinct levels of work groups - termed “first-order teams” and “second-order teams.” Depending on the phase of activity, first-order and second-order teams are identified, each having it own unique structure, composition, communications, goals, and challenges. Several specific teams are highlighted as case examples. Limitations of this approach are discussed, as are potential benefits to ongoing and planned research activity in this area.

Systems modeling of space medical support architecture: Topological mapping of high level characteristics and constraints

The challenges associated with providing medical support to astronauts on long duration lunar or planetary missions are significant. Experience to date in space has included short duration missions to the lunar surface and both short and long duration stays on board spacecraft and space stations in low Earth orbit. Live actor, terrestrial analogue setting simulation provides a means of studying multiple aspects of the medical challenges of exploration class space missions, though few if any published models exist upon which to construct systems-simulation test beds. Current proposed and projected moon mission scenarios were analyzed from a systems perspective to construct such a model. A resulting topological mapping of high-level architecture for a reference lunar mission with presumed EVA excursion and international mission partners is presented. High-level descriptions of crew operational autonomy, medical support related to crew-member status, and communication characteristics within and between multiple teams are presented. It is hoped this modeling will help guide future efforts to simulate medical support operations for research purposes, such as in the use of live actor simulations in terrestrial analogue environments.