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U.S. Department of Health and Human Services

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Research Project: Surface Contamination of Medical Devices

This key research project focuses on investigating and implementing advanced laser spectroscopic, hyper-spectral and functional imaging methods for non-destructive sensing and analysis of biochemical contaminates on medical device surface.

Task 1: Advanced Laser Spectroscopy Approaches to Sensing and Analyzing Chemical and Biological Contaminations at Medical Device Surfaces

Principal Investigators:
Xin (Sofia) Tan, PhD (contact: xin.tan@fda.hhs.gov)
Do-Hyun Kim, PhD
Ilko K Ilev, PhD

The project is part of a multi-divisional research program within the FDA-designated CDRH scientific priority areas, the goal of which is to utilize new technologies that can be used in the field to rapidly assess the presence and identification of contamination on medical device surfaces. Therefore it is closely aligned with the mission of FDA in promoting public health by ensuring the safety of medical devices.

Medical devices include a variety of devices used both externally and internally for diagnostics and therapeutics, as well as indwelling devices such as implants and intraocular lenses. Surfaces of medical devices are of critical importance as they control many clinical properties including the immediate response from the biological host. Surface contamination of medical devices is commonly encountered, such as molecular contaminants from manufacturing, packaging, and sterilizing/disinfecting residues, trace heavy metals on dental crowns, protein pathogens on surgical instruments, and bacterial biofilms on implants.

Many of the sophisticated and sensitive surface techniques such as Secondary Ion Mass Spectrometry (SIMS), X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) are too expensive and complex to handle (high vacuum is often required) for in-situ contamination analysis. Currently applied clinical methods are based on swab/wipe sampling and subsequent extraction and ex-situ detection using techniques such as High Performance Liquid Chromatography (HPLC) or Enzyme Immunoassay (EIA). These methods for surface contamination analysis suffer from inefficiency and inaccuracy. New technology platforms for rapidly assessing the presence and identification of surface contaminants are needed. 

Laser spectroscopy with fiber-optic sensing technology offers the advantage of being nondestructive, sensitive and efficient with the potential to be miniaturized for in-situ applications. We will develop label-free detection approaches based on Fourier Transform Infrared (FTIR) and Raman spectroscopy with fiber-optic sensing for surface contamination.

Several areas of focus include (a) detection of residual sterilant/disinfectant contamination on device surfaces, (b) sensitive detection of protein contamination on surgical instruments, and (c) detection of contaminants from polyvinyl chloride (PVC) packaging plasticizers or lubricant constituents. We will validate the developed technologies and characterize the designed sensing systems in terms of chemical specificity, sensitivity, sample processing and data analysis.


Advanced Laser Spectroscopy Approaches to Sensing and Analyzing Chemical and Biological Contaminations at Medical Device Surfaces; (Left): Surface contamination can occur on contact lenses, implants, catheters, stents, and needles. Common Contaminants are adhesives, fibers, inorganic oxides and salts, metal ions, metal particles, mold release agents, organic residuals, polymers, polymer additives, silicones, and surfactants. (Top Right): Fourier Transform Infrared (FT-IR) spectroscopy and microscopy. (Bottom Right): FT-IR reflectance microscopy of surface test soil from surgical instrument.



Task 2: Investigation of Combined Hyper-Spectral and Functional Imaging Methods for Surface Contamination Detection on Medical Devices

Principal Investigators:
Do-Hyun Kim, PhD (contact: do-hyun.kim@fda.hhs.gov)
Xin (Sofia) Tan, PhD
Ilko K Ilev, PhD

The project is to investigate two state-of-the-art technologies that really stand in the forefront of biophotonics imaging modalities: Hyperspectral Imaging and Functional Imaging. The basic idea of hyperspectral and functional imaging is similar: Instead of acquiring only integrated spectral intensity at a pixel point of a 2D image, these techniques utilize the full spectrum of each pixel and to identify the spatial or temporal correlations. Hyperspectral imaging is a subcategory of spectral imaging, which collects spectral information of each pixel instead of acquiring intensity only. Hyperspectral imaging acquires more finely separated spectrum over a wide range of spectrum, which distinguish it from multispectral imaging. Adding functional imaging centers such as isotopes, chemicals, or biological markers enable to trace only functional information of the functional centers, thus this modality is called functional imaging. These technologies have been widely adapted to detect or measure changes in metabolism, blood flow, change in chemical composition, change in physical properties, etc. These techniques will provide an excellent platform to detect surface contamination of medical devices, especially contamination by chemical elements.

We have two laboratory systems that can perform these modalities: a multi-functional confocal microscope combined with broadband spectrophotometer and a spectrometer-based Fourier-Domain Optical Coherent Tomography (FD-OCT) system. Both systems are capable of collecting spectral information and to form 3D (2D spatial information + 1D spectral information) images. We will investigate this technology to detect any surface contamination on medical devices. We will further investigate in the future other hyperspectral and functional imaging equipment such as 2D spectral camera or imaging spectrometer. To further extend the limit of spectral imaging technology, we will partially adapt the principle of laser-induced breakdown spectroscopy where normal spectral imaging does not provide enough information to detect contaminants on the surface of medical devices. Nd:YAG laser pulses will be used to generate plasma on the surface of the medical devices, which in turn will produce atomic emission spectra from specific contaminants.


Hyperspectral Imaging for Surface Contamination Detection on Medical Device Surfaces 
Hyperspectral Imaging for Surface Contamination Detection on Medical Device Surfaces; (Top): Conventional Imaging Method: Only the intensity information was recorded for each pixel of the object. (Bottom Left): Obtain spectral information for each pixel. (Bottom Right): Stack them together so that each slice of images at different wavelengths gives different spectral images.