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All things related to SPR technology

Easy SPR experiment set-up: the Affinité sensor difference

One common SPR optical set-up widely used by most commercial SPR instruments involves a prism coupler. This component couples light to a metal surface, creating a phenomenon known as surface plasmons.

In traditional SPR experimental set-ups, it is essential for the user to adhere a glass chip coated with a thin layer of gold to a prism using an index matching fluid. The gold-coated glass chip is illuminated through a prism positioned beneath the chip substrate. The space between the prism and the chip is filled with the index matching fluid, typically immersion oil or elastomers, which has an appropriate refractive index to facilitate the interaction of light with the sensor chip to generate the surface plasmon polaritons.

Figure 1. Traditional SPR set-up using a gold-coated glass slide adhering on a prism using immersion oil

However, the use of this fluid can present several challenges. Its nature as an immersion oil means it can flow to the sides of the chip, potentially impacting the positioning of the gold-coated chip on the prism and complicating its installation in the flow cell. Additionally, the fluid's slippery nature can cause the chip to move on the prism, potentially affecting the optical alignment and hence the signal. Furthermore, the spread of the fluid upon contact necessitates careful cleaning of the flow cell before the installation of the next gold chip, significantly increasing both the system set-up and cleaning time.

Affinité's SPR Advantage

In contrast, Affinité's lensless SPR systems offer a more efficient solution. These systems feature a gold-coated sensor that combines the gold layer directly onto a miniature prism substrate, thereby eliminating the need for an index matching substance. This feature of the sensor substantially reduces the time taken to install sensors and eliminates the need for adding immersion oil.

Figure 2. Affinité's gold sensor combining the gold layer with the miniature prism

Figure 3. Comparison of Affinité's gold sensor to gold chip used in other SPR systems

The sensor installation process with any of Affinité's systems is straightforward and user-friendly. Installing our sensors involves simply opening the arm, placing the sensor face down in the cavity, closing the arm, and passing through the liquid in channels. The process requires no additional steps or optical alignment.


Affinité's lensless SPR systems aim to improve SPR experiments by simplifying sensor installation, reducing set-up time, and addressing challenges commonly encountered with traditional set-ups. We strive to contribute to the advancement of SPR analysis in various application fields, with the hope of making it more accessible and user-friendly for researchers and scientists.

To learn more about our devices or request a demo, please check out our website or contact us at


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