A pinch elastometer for soft tissue

Study on Deposition Characteristics of Microparticles in Terminal Pulmonary Acini by IB-LBM

As an indicator of health risk, the deposition of microparticles in terminal pulmonary acini is of great significance in the medical field. To control particulate pollution and optimize aerosol delivery, it is necessary to perform an in-depth study of the microparticle deposition in terminal pulmonary acini; however, little research has been done on this topic. This paper proposes a respiratory movement model of terminal pulmonary acini using an immersed boundary–lattice Boltzmann method. In addition, we explored the effect of gravity direction, respiratory rate, microparticle diameter, and other parameters on the microparticles deposition process and distribution, under the airflow in the acinar wall. It was found that the deposition of microparticles is sensitive to gravity direction, and the growth of the respiratory rate increases the rate of microparticle migration and deposition. It was observed that the gravity effect is enhanced by increasing the diameter of microparticles, causing a high deposition and dispersion rate. The study reveals the dynamic correlation between the respiration process and the movement of microparticles, which is of reference value to figure out the pathogenicity mechanism of inhalable particles and to optimize the aerosol delivery.

Comparison of the surface wave method and the indentation method for measuring the elasticity of gelatin phantoms of different concentrations

The speed of the surface Rayleigh wave, which is related to the viscoelastic properties of the medium, can be measured by noninvasive and noncontact methods. This technique has been applied in biomedical applications such as detecting skin diseases. Static spherical indentation, which quantifies material elasticity through the relationship between loading force and displacement, has been applied in various areas including a number of biomedical applications. This paper compares the results obtained from these two methods on five gelatin phantoms of different concentrations (5%, 7.5%, 10%, 12.5% and 15%). The concentrations are chosen because the elasticity of such gelatin phantoms is close to that of tissue types such as skin. The results show that both the surface wave method and the static spherical indentation method produce the same values for shear elasticity. For example, the shear elasticities measured by the surface wave method are 1.51, 2.75, 5.34, 6.90 and 8.40kPa on the five phantoms, respectively. In addition, by studying the dispersion curve of the surface wave speed, shear viscosity can be extracted. The measured shear viscosities are 0.00, 0.00, 0.13, 0.39 and 1.22Pa.s on the five phantoms, respectively. The results also show that the shear elasticity of the gelatin phantoms increases linearly with their prepared concentrations. The linear regressions between concentration and shear elasticity have R(2) values larger than 0.98 for both methods.

Soft tissue elastometer

We have developed a device entitled the 'Tissue Elastometer' (TE) for evaluating the Young's modulus of soft tissues. Soft tissue specimens are compressed between the object plate of an electronic balance and a linearly actuated indenter with a small rounded tip. The hardware of the device was designed such that a deformation model for semi-infinite media is applicable for calculating the Young's modulus of test specimens from their collected force-displacement data. Force-elongation measurements were performed on long strips of cured silicone mixtures to produce calibrated, tissue-mimicking test samples for the TE in a Young's modulus range of 10-400 kPa. When tested with the TE, the Young's moduli of the silicone samples demonstrated accuracy to within 1-10% of their calibrated values. Testing on excised tissue samples (fresh store-bought poultry breast; bovine liver, kidneys, hind shanks; porcine) was also performed, and a repeatability of elasticity measurements was demonstrated in the range of 8-14%. Results indicate that the TE can be effectively used in laboratory and clinical environments to evaluate the elasticity modulus of tissues.