In Vitro Sunscreen Testing
- TRI Princeton
- 6 hours ago
- 4 min read
TRI PRINCIPLES OF SKIN MEASUREMENT SCIENCE AND CLAIMS COURSE
15-16 September 2026
The TRI Principles of Skin Measurement Science and Claims course will feature a topic in which TRI is a world-leader: the testing of sunscreen formulations and products using vibrational spectroscopy. The TRI course is an annual event, specifically designed for those involved in the development of new skin care products. The two-day program is a must-attend for anyone who needs to build their knowledge rapidly in skin biology, the measurement techniques used in the development of new skin products, and best practice in claim substantiation and experimental design. Register to attend live or online. All lectures are videoed and available on playback. Live places are very limited, so do not delay!
Lab demo at TRI of Horiba SkinProbeTM Raman spectroscopy system suitable for use in clinical testing
TRI: A Leader in Skincare Research and Innovation
At TRI we’re known to undertake research at the forefront of science, often in conjunction with companies and organizations who are also world-leaders. In recent years, the changes seen in the skin upon exposure to high temperatures has become a key area of interest across the field of cosmetic science. This work has direct – and tangible – application to the field of sunscreens, both in terms of product longevity once applied and active ingredient penetration into the skin, and is highly applicable in light of the recent weather patterns seen across Europe, the United States and beyond. In fact, over the past five years the TRI Team have given nearly 20 talks, showcasing our capabilities and expertise in this key area.
It all started with our expertise in vibrational spectroscopy (which includes both Raman and Infra-Red (IR) techniques). While both IR and Raman have been used extensively within analytical chemistry laboratories for many years, their use within cosmetic science to probe penetration of actives, or how a product behaves in vivo, has been stilted due to technological limitations. However, a new generation of instrumentation has enabled IR and Raman measurements to be undertaken on biological samples, opening the door to wider application of these powerful techniques in formulation development and actives analysis.
It’s this technological development that TRI has exploited across a range of cosmetic applications. However, when it comes to sunscreens and skin protection, one of our initial disclosures was relating to their use in the evaluation UV filter penetration into human skin samples, which then led onto our work that visualizes retention of sunscreen on the human face over time (3D facial mapping).
Spectroscopy for Active Ingredient Tracking
Research undertaken by TRI, and published in the academic literature, has used FT-IR imaging in combination with tape-stripping to track the penetration of the organic UV filter avobenzone into the stratum corneum (SC). It was found that upon topical application under controlled conditions, avobenzone was primarily deposited upon the SC, as expected, but also penetrated into the SC, with traces of material detected up to 6 layers deep. In the same study, the effect of encapsulating the active ingredient was also investigated. It was shown that encapsulation of avobenzone, an organic UVA filter, with octocrylene, a photo-stabilizer, resulted in no penetration of the organic material into the stratum corneum (SC), and the durability of the sunscreen was markedly improved. Furthermore, the photostability of the active compounds was also improved.
FTIR images generated to visualize and comparison of avobenzone penetration inside the SC for different skin samples. For each sample the FTIR images were scanned before (control), after topical application on the sunscreen formulation and after 8 sequential tape strips. Taken from Gourion-Arsiquaud and co-workers: https://doi.org/10.1016/j.ejps.2018.06.001.
Spectroscopy for Physical Changes to Skin During Thermal Exposure
A second key area where vibrational spectroscopy is being applied is in the liquidity – or more specifically the lipid fluidity – of the SC lipids during thermal exposure. Work completed as TRI has shown that the packing of SC lipids changes during thermal exposure, even at temperatures as low as 40 °C. This is important for the development of sunscreen-based products or new products containing SPF protection, especially in relation to efficacy testing in real-world applications.
For example, during testing of sunscreen efficacy under laboratory conditions (20 °C) and physiological conditions (30 °C), all the standard formulations investigated exhibited high surface retention on the SC, with negligible skin penetration. This was in stark contrast to temperatures likely encountered during outdoor exposure in a hot summer (42 °C), where the sunscreen’s performance in these standard formulations was significantly compromised: each showed a marked decrease in surface retention and a concomitant increase in skin penetration, likely related to changes in SC lipid packing upon exposure to heat. However, formulations where bio-adhesive technology was used showed minimal differences between laboratory-based and real-world testing results, maintaining superior surface residency and providing a robust barrier against percutaneous absorption even under high thermal stress.
TRI to Support Sunscreen Formulation and Product Development
The TRI team are highly experienced in the use of state-of-the-art techniques to measure sunscreen product efficacy and active penetration. The Principles of Skin Measurements and Claims course 2026 (also known as the TRI Skin Course) is an excellent opportunity to meet the team behind these innovations, see our facilities, and listen to the latest developments that we’ve made the field of skin. The intensive two-day program is designed for anyone who needs to build their knowledge rapidly in skin biology, the measurement techniques used in the development of new skin products, and best practice in claim substantiation and experimental design.
