the supporting tissue component. Of course, in practice models require more than two tissue components to accurately simulate the response of the target anatomy, and each of these components would typically employ three or more tissue analogs. SynDaver™ elastic arteries, for example, employ separate tissue analogs for intima, media, and adventitia, and each of these layers are individually comprised of multiple materials.

Synthetic Tissue Analogs
SynDaver™ Labs' synthetic human tissues are designed to mimic one or more properties of a specific target tissue, and in order to develop each analog structure two sets of design inputs (modeled properties and data source) must be defined. The modeled properties are determined by selecting and prioritizing the chemical, physical, and mechanical properties that the analog must mimic, and strictly speaking these may vary depending on the type of device under test, the target anatomy, and the general objective of the testing. For example, if one test objective is to determine the intimal damage caused by a device tracking through the femoral artery, abrasion resistance would be included in the target list for the tissue analog. In addition, if it was also desired to simulate the tendency of the device to penetrate the artery wall then penetration resistance or shear strength (a related mechanical property) would be included in the list as well. Any number of properties may be added to this list. However, as the number of modeled properties grows it becomes progressively more difficult to simultaneously satisfy all of the design requirements. In fact, if a particular tissue or organ must mimic more than three mechanical properties it will typically be necessary to employ multiple analogs to meet design requirements.

The data source which will form the design basis for the new tissue analogs must also be defined. First of all, it must be decided if the analogs will be formulated to mimic the properties of human tissues or animal tissues (either living or dead). Once this question is answered, the relevant data may either be drawn from the literature or generated directly by performing the appropriate tests on tissue samples. However, it should be noted that vastly superior results will always be achieved by performing the relevant tests directly. The results of mechanical-physical tests are highly dependent on test conditions, and controlling the test gives the designer control over such conditions. More importantly however, it allows the candidate tissue analogs to be tested and subsequently validated under exactly the same conditions as the target tissue.