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Développement d’un dispositif de caractérisation du degré de brûlure chez l’humain par mesures électromécaniques

ABG-105354 Thesis topic
2022-05-05 Public funding alone (i.e. government, region, European, international organization research grant)
LEM3/ENIM Université de Lorraine
Metz - Grand Est - France
Développement d’un dispositif de caractérisation du degré de brûlure chez l’humain par mesures électromécaniques
  • Engineering sciences
  • Health, human and veterinary medicine
Burnt skin, electromechanical measurements, constitutive laws of soft biological tissues, design of experimental devices, Biomechanics, Computer Assisted Design, Machining.

Topic description

Development of a device to assess the burn depth using electromechanical properties of human skin

LEM3, Université de Lorraine, 57000, Metz, France

DCAC, Université de Lorraine, 54000, Nancy, France

keywords: Burnt skin, electromechanical measurements, constitutive laws of soft biological tissues, design of experimental devices, Biomechanics, Computer Assisted Design, Machining.

Context: Skin burns cause serious physical and psychological sequelae, despite progresses in burn care. Burn wound depth is a significant determinant of severity and is classified in 3 degrees. First-degree burn affects only epidermidis while third-degree burn leads to destruction of dermal and epidermal layers. Both are easily diagnosed while second-degree partial thickness burn can be dissociated into superficial and deep burns. For the latter, spontaneous healing is impossible and requires an adapted therapeutic strategy. Differentiating superficial from deep partial thickness burn is clinically difficult. Wound healing time remains the only diagnostic criteria, delaying skin repair procedure. Thus, an early estimation of burn depth is crucial for vital and functional prognosis.

The electrical impedance properties of the skin were investigated and it is established that the electrical resistance resides foremost within the stratum corneum (the upper layer of the epithelium). A burn wound should therefore lead to a reduction in skin electrical resistance because it alters epidermal layers.

We would like to design and validate an innovative device based on the measurement of electrical resistance of the skin to improve early diagnosis. Measurements of electro-mechanical properties will be carried out on patients during dressing replacement both on healthy and wounded zones. We assume that variations in skin biophysical properties may be related to changes in the organization of the epidermis during the wound healing. Thus, an accurate measurement of the electrical resistance of the skin can be used to establish an early prognosis of healing capacity.

The concept already validated on an animal model must be assessed on human with a prototype designed on-purpose. A preliminary study was carried out in our laboratory, using a pig skin ex vivo model. Two electrodes in contact with skin gave information about its electro-mechanical properties. Undergoing mechanical dermabrasion with different depths, 44 measures and biopsy allowed assessing burn depth through anatomopathological examination. Through histological degree is not exactly superimposable to clinical one, the measurement has validated the concept.

With the respect to the approach partially deployed in cosmetic dermatology through electrical measurements, the major scientific innovation is to combine electrical and mechanical measurement while performing skin palpation to get electro-mechanical properties of the skin. Adding mechanical measurements ensures burn depth assessments reliability even though burn location and/or skin quality induce complicate measurements. Raw data will have to be processed to decouple information thanks to multiphysics models and simulations developed. These innovations will allow accurate clinical diagnosis and more efficient patient care through regenerative medicine.

Objectives and scientific challenge:

Despite advances in regenerative medicine, burns still cause severe physical and psychological trauma. Assessing the depth of the burn is important for both the vital and functional prognosis and is one of the major research challenges today. Burn depth, classified in three degrees according to their depth (Figure 1), can lead to the destruction of the epidermal and dermal layers. The second degree is divided into superficial and deep degrees, which are difficult to recognise precisely before the healing stage. Indeed, deep burns do not heal spontaneously and require special therapeutic strategies, mainly based on skin grafting. This procedure procedure may be unduly delayed if a misdiagnosis is made. So, a rapid estimation of burn depth is crucial. The current practice for diagnosis is based on the practitioner's expertise, which can generate uncertainties in the management and patient recovery.

The determination of the electrical impedance of the skin under controlled mechanical loading has been investigated highlighting the fact that the electrical resistance of the skin is mainly due to the stratum corneum. Considering that the variations of the electromechanical properties of the skin are related to its state (burnt, scarred or healthy) as shown in the literature [Ye and De 2017; Miklavcic et al 2006, Swain et al 1985], we would like to validate an innovative procedure to improve the estimation of the degree of burns and consequently the care of regenerative medicine. Measurements of these properties will be made during patient care on healthy and burned areas using a specifically designed device. We hypothesise that variations in the electrical properties of the skin are related to the destruction and subsequent restructuring of epidermis during the healing process. Thus, an accurate measurement of skin electrical resistance could provide an early prognosis of wound healing capabilities in burn patients. The major scientific innovation of this project lies in the coupling and interpretation of electrical and mechanical measurements using simulation tools.

The thesis plan would be :

  • Design and manufacturing of the clinical measurement device (LEM3): design and manufacturing of a metallic probe according to the clinical standards; design and setting of the mechatronics environment

  • Clinical measurement campaign (DCAC/CHR Metz Thionville): the clinical part of the study, i.e. the inclusion and follow-up of patients with the measurement of the cutaneous electrical resistance using the specific tool in the intensive care unit and continuous monitoring of the Burns Treatment Centre of the CHR Metz Thionville. It will require working on the writing of the protocol for the ethics committee (ANSM application).

  • Analysis and valorisation of the results (LEM3/DCAC/CHR Metz Thionville): validation of the characterisation procedure of the burn level, comparison of the electromechanical results with the numerical models, technological transfer or proposal of a new prototype

Starting date

2022-10-03

Funding category

Public funding alone (i.e. government, region, European, international organization research grant)

Funding further details

Presentation of host institution and host laboratory

LEM3/ENIM Université de Lorraine

Les équipe ainsi que les laboratoires sont présentés sur le site internet

Candidate's profile

Profile: Master degree or equivalent in Biomechanics, Mechanics or Physics.
Skills:
    • Design of experimental devices (mechanical and electronic aspects, sensor development, programming)
    • Mechanical testing on non linear materials
    • Finite element simulations
    • Strong interest in biomechanics
    • Capacity to work in a clinical environment (measurements on patients)

2022-06-12
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