Over the past few decades, various non-invasive approaches, such as elastographic techniques, have emerged to quantify the elastic properties of tissues. However, despite their promising performance, these imaging techniques are expensive and complex to use. This work presents a new, simple, real-time, and low-cost non-invasive approach for the biomechanical characterization of skin.
This technique is based on an impact analysis method. A force signal is recorded during the impact of an instrumented hammer on a cylindrical punch in contact with the tissue to be characterized. This signal comprises several peaks resulting from the punch's rebounds between the hammer and the soft tissue. An indicator of tissue stiffness is deduced from the time interval between these peaks. Using various soft tissue phantoms (homogeneous and bilayered), in vitro studies were designed to determine the performance of this new method (in terms of reproducibility, volume of interest, and stiffness and spatial sensitivity). A comparative study was then conducted with other devices such as Cutometer® (a reference method in the cosmetics industry), MyotonPro® (widely used in research), IndentoPro®, and Durometer.
In light of the results, a decision-support device (MVP) to assess the mechanical properties of skin has been developed. Various aspects will need to be clarified to complete the development of the future medical device. New indicators of these phenomena could be derived from the force signal. Alternatively, these mechanical properties could also be estimated using an inverse model-based inversion approach.
Following the initial measurements on biological tissues, subsequent investigations should aim to approximate future utilization conditions, specifically in vivo skin characterization. Until a suitable prototype for clinical studies is developed, research will be conducted using animal models. The protocol for monitoring wound healing mechanics and hyaluronic acid injection-induced hydration could be reproduced with a new animal model, more consistent with the human model in terms of skin structure, and by extending the period and reducing the measurement intervals of the protocol to refine the results.
A clinical study involving human subjects will be possible with the final version of the product after having cleared all regulatory requirements. We have validated the class of the set-up as the regulatory pathway in the context of a medical device, which implies setting up a Quality Management system and obtaining pre-series on which various tests will need to be carried out.
We have performed an additional market study to validate our choices. Moreover, we have established a clear marketing plan. Overall, the company will retain control over the production and know-how of Smart-Hammer through its subcontractors. We already have contacts with major companies who are interested in the future product. We now consider the creation of the company in the direction to perform the clinical transfer.
