Rapid Verification of High Performance Plastics in Medical and Surgical Applications

High performance plastics are widely used in surgical instruments, medical devices, and in other instruments that need frequent autoclaving.

Plastics in these applications need to survive repeated sterilization cycles with no loss of integrity for the equipment. In addition, the globalization of the supply chains of these raw materials or fabricated components results in highly possible and expensive material mix-up.

The Inspector 500 Raman analyzer (Figure 1) from SciAps reliably verifies many grades of high performance plastics. It is equipped with a unique 1030nm laser source to negate the high fluorescence background, which plagues more traditional 785nm Raman analyzers.

The Inspector 500 Raman analyzer

Figure 1. The Inspector 500 Raman analyzer

SciAps Handheld Raman Analyzers

SciAps handheld Raman analyzers are a user-friendly, fully non-destructive technique for polymer verification. Many food industry instruments and surgical equipment use either Polysulfone (PSU) or Polyphenylsufone (PPSU) owing to their ability to handle elevated temperature conditions in repeated autoclaving cycles.

Nevertheless, the need for high-cost, specialized plastics also presents the opportunity for out-of-spec substitutes, or material mix-ups. One implant manufacturer selected a SciAps Raman analyzer to distinguish between Polyetheretherketone (PEEK) and Ultra-High Molecular Weight Polyethylene (UHMWPE), which are difficult to be differentiated because of their similar look and feel.

Working Principle of SciAps Handheld Raman Analyzers

In SciAps Handheld Raman Analyzers, molecular signatures or "fingerprints" of common plastics are stored in onboard libraries by the Raman unit. Characteristic molecular vibrational patterns are created by directing the laser light from the equipment onto an unknown polymer. The patterns then re-direct or "scatter" photons back into the device at various frequencies to generate a characteristic "fingerprint" for each polymer.

This fingerprint is then analyzed and compared with data in onboard libraries by an onboard detection system and processor to find a match and reveal the correct polymer type for the sample. SciAps Handheld Raman Analyzers are highly customizable, enabling easy addition of new fingerprints for new or proprietary materials with no need to share any such samples or data with SciAps.

Raman spectra for PSU and PPSU from an Inspector 500 Raman analyzer

Figure 2. Raman spectra for PSU and PPSU from an Inspector 500 Raman analyzer

Figure 2 shows the Raman spectra for PSU and PPSU acquired by an Inspector 500 Raman analyzer. Different peak structures can be clearly observed from the "fingerprints" acquired for the two different plastics, both in intensity and location. Hence, the SciAps analyzer is capable of clearly verifying these materials regardless of their similar molecular structure.

Key Features of Inspector Class Raman Analyzers

The Inspector class Raman analyzers have the best ergonomics of any handheld Raman, enabling to be used by all end users. The Inspector is well balanced, tapered and features a well-placed wrist strap, facilitating easier operation compared to "brick shaped" analyzers that normally require two hands to hold. It is equipped with a bright, color touchscreen with intuitive, icon-driven operation.

It is difficult to operate most touchscreens if users wear protective handgear. Conversely, SciAps’ innovative thumbwheel drive is within easy reach, facilitating complete control of the analyzer even with gloves on.

Inspector 500 Raman Analyzer

The newest generation handheld Raman analyzer from SciAps is the Inspector 500, which is the first Short-Wave InfraRed (SWIR) Raman handheld analyzer in the world offered in a watertight, dustproof package. SWIR Raman represents the use of the 1030nm wavelength laser in the Inspector 500 Raman analyzer. This laser can analyze more number of compounds by suppressing fluorescence.

Compared to 1064nm versions, the Inspector 500 uses very low power and enables sealing against dust and moisture. It has to be washed or rinsed to prevent sample contamination or cross contamination. It provides unprecedented analysis power, ergonomic ease, and environmental ruggedness.

The common 785nm Raman laser is not suitable to analyze some high performance plastics due to the production of high fluorescence by the compounds in the material at that wavelength. This leads to a high featureless background that distorts the characteristic Raman peaks. This is illustrated in Figure 3, where PPSU is analyzed at both wavelengths. The Inspector 500 equipped with the 1030nm laser provides a clear spectral pattern, thereby enabling highly confident material verification. Conversely, the 785nm laser yields a nearly featureless spectrum. The 1030nm laser delivers reliable determination, day in and day out, of high performance plastics.

Raman spectra for PPSU from the Inspector 300 (785nm) and Inspector 500 (1030nm)

Figure 3. Raman spectra for PPSU from the Inspector 300 (785nm) and Inspector 500 (1030nm)

This information has been sourced, reviewed and adapted from materials provided by SciAps, Inc.

For more information on this source, please visit SciAps, Inc.

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