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Bio-engineered Interfaces
 
(Faculty participants: Hoath, Mac Neil, Bhansali, Lindsey, Hilbelink, Kumar, Malik) Areas: Skin, Clinical Sciences, Anatomy, MEMS, and Chemistry
 
Many biological processes produce physical, electrical, or chemical alterations that may be monitored by close approximation of a micro sensor to the surface of the skin. Vital signals of the human body such as EEG, ECG, and EMG are regularly measured by the placing of non-invasive electrodes on appropriate parts of the skin. The primary long-term goal of the project is to understand the underlying phenomena and dynamics of the human body with the help of skin as the interface. The more intimate the skin/sensor interface the better the function of the sensor. Optimizing this interface without compromising the well being of the organism is a real challenge from both a biological and an engineering point of view. This group of studies will focus on how to best design sensors as minimally obtrusive devices and explore methods to produce a virtual skin model for incorporation into classic engineering design systems. Our objective is to optimize the capture of a wide range of signals (electrical activity, thermal conditions, skin hydration), and to process and analyze this data for correlated with the physiological state of an individual.
 
3D model of human skin for visualization and finite element modeling
 
Skin samples containing the three layers of the integument, will be taken from the thorax, abdomen, back, limbs and scalp, immediately fixed and processed for light microscopy. Serial sections will be stained allowing for the visualization of the various cellular and extracellular components. A single composite digital montage image of each section will be produced using a collection of photomicrographs taken at high resolution through a microscope. These montage images, stacked in Z space and registered in X and Y, result in a digital data set representing the entire volume of the original tissue sample. Following a segmentation process, cellular components may be accurately viewed, either individually or collectively, in 3D space. The result will be a virtual skin model for use in a CAD environment, for visualization, finite element analysis and/or simulation studies.
 
Subsequent phases of the study will involve the embedding of physiological, biomechanical biochemical, and molecular data into the virtual model to make the model more robust for mathematical modeling. This information will be obtained from existing literature as will as actual analysis of bench related analyses conduct in our laboratory using such tools as classic tensile strength testing to atomic force microscopy.
 
Skin/sensor interface for fluid based chemical analysis
 
A non-invasive, CPS micropore binding interface that could be the front end for the microfluidics based systems will be developed. We postulate that wicking of endogenous surface lipids from the skin into the pores will allow device adhesion. This non-contact/non-invasive sampling technique overcomes the problems of invasive monitoring. The liquid from the micropores in the active area is wicked up because of the capillary action and gets introduced into the sampling chamber. The micropores, however, also act as a check valve for the fluid from because of large pressure drops across them, ensuring unidirectional flow of surface analyte.
 
Skin/sensor interfaces for acoustic information
 
Current microsensor technology, wireless communication, sound waveform analysis, and pattern recognition will be applied to auscultation. Sounds produced by the heart will be the primary focus of the study. The initial goal of this study will be to evaluate current electronic stethoscope technology and the features of clinically relevant heart sounds to determine the state of the art and the scope of the challenge. A microsensor-based device will then be designed to interface between medical personnel and the patient's skin to optimally sense and capture all relevant auscultation information in a digital format.
 
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