Lifelikeness in multilayered digital prostheses

Abstract

The appearance of the skin is dependent on the optical properties of the various layers of tissue and the presence of pigments. In order to reproduce the lifelikeness of the skin in developing digital prostheses, a multiple layered moulding technique was utilised. The prosthesis was moulded in two coloured layers, an outer layer and an inner layer. Four combinations of multiple coloured layers and two single coloured layers varying in their optical properties and base colours were assessed. In two groups an additional intermediate layer of detailed colours was added between the two layers, to enhance the creaselines, nails, blood vessels, and other features. All prosthesis were moulded to a total thickness of 0.6 mm. This method of moulding was based on the anatomical characteristics of the epidermal and dermal layers of the skin and their optical characteristics. The aim was to determine which combination of multiple layers gave the best outcome and made the prosthesis look lifelike in appearance. The appearance and lifelikeness of the prostheses were qualitatively assessed by a panel of assessers divided according to their vocation. The study showed that the best combination for moulding the prosthesis in multiple layers was to have the outer layer translucent and the inner layer opaque. An intermediate layer should be incorporated to enhance the more prominent surface features and the nails. The base colour of the inner layer should be darker than the outer layer to allow the intermediate layer to have a reflective background.

Illusory Sense of Human Touch From a Warm and Soft Artificial Hand

“…The study suggests that the object being viewed by the participants must fit with a reference model of the body in order to maintain a coherent sense that the object can be a part of the body. Considerable advances have been achieved to make prosthetic hands and fingers indistinguishable from the missing body parts not only in terms of anatomical structure [18,19] but also in the replication of skin tone, pores, and hair [20,21].…”

Metamerism in aesthetic prostheses under three standard illuminants — TL84, D65 and F

“…Extraneous light was excluded during the colour-matching processes. The colour formulation for the inner opaque silicone layer was achieved from previous trials 1997) such that when laminated with the outer translucent layer, the composite colour of the prosthesis matched the left index finger of Subject C. The colour for the outer translucent silicone layer was the same for all 4 prostheses (Table 1).…”

Mechanical and Morphological Effect of Plant Based Antimicrobial Solutions on Maxillofacial Silicone Elastomer

“…The prostheses can be exposed to mucosa, moist air and skin secretions (such as sweat, sebum and other products secreted by the skin), subsequently leading to a multilayer biofilm formation [ 9 , 17 , 18 ]. Biofilms are a structured community of cells enclosed in a self-produced polymeric matrix adherent to an inert or living surface [ 19 ].…”

“…Furthermore, the biofilm architecture, i.e., the layer on the surface of a prosthesis in which the cells are embedded in extracellular polysaccharide matrix, results in poor penetration of antibiotics through that layer [ 22 ]. Furthermore, nutritional support either extrinsically or intrinsically from within the prostheses will sustain further growth of these micro-organisms [ 17 ]. Disinfection of elastomers could alter their surface characteristics and the bulk of the material due to the extraction of some compounds from the matrix to disinfection solutions or the water as indicated in many studies [ 23 , 24 ].…”