The behaviors of biomaterials are influenced by a multitude of factors including temperature, mechanical load, and biochemical environments. The dynamic equilibrium of organism within a multiphysical field is crucial for its physiological functions. Therefore, a comprehensive investigation into the bio-thermo-mechano-electrophysiological behaviors is of great significance for the elucidation of pathologies and the development of effective diagnostic and therapeutic strategies. Such inquiries inherently require a multidisciplinary approach, necessitating the integration of diverse disciplinary knowledge and the pioneering of innovative cross-disciplinary research. The core idea is to discover key scientific questions, identify interdisciplinary disciplines, integrate disciplinary advantages, promote theoretical and technological innovations, and bring new breakthroughs in the biomedical field. With the discovery of DNA double helix structure in Cambridge University as the background, and the tissues of brain, skin, and teeth, etc. as examples, this paper introduces the evolution and intension of bio-thermo-mechano-electrophysiology, a new interdisciplinary subject.

The brain is the highest nerve center regulating physiological behaviors and functions. Brain tissue is a saturated porous material composed mainly of solid phase and liquid phase. Interactions between the solid phase, the liquid phase and the physiological environment (temperature in particular) are manifested in the coupled thermo-mechanical behaviors of brain tissue, and affected by internal temperature, seepage and stress fields. Characterization of the coupled thermo-mechanical behaviors of brain tissue is the key to understanding brain function and disease pathology. Firstly, the thermal and mechanical properties of brain tissue measured via different experimental methods were introduced, with a particular focus placed upon the effects of the strain rate and the temperature. Theoretical and numerical models describing the coupled thermo-mechanical behaviors of brain tissues were then summarized, including mechanical models, heat transfer models and coupled thermo-mechanical models. Finally, this important multidisciplinary field was summarized and prospected.

Sustained high overloads often acting during aerospace flights can significantly affect the passenger brain function dependent on the mechanical behavior of brain tissue and highly correlated with load characteristics. To predict the mechanical responses of human brain under sustained high overloads, the poroelastic constitutive model was adopted to characterize the mechanical behaviors of brain tissue. Built on an idealized 1D multi-layer structural model for human heads, the poroelastic control equation and the state transfer matrix for the brain tissue were derived. Through the Laplace transform and its inverse transform, the spatiotemporal distribution of the intracranial fluid pressure, the intracranial fluid seepage velocity, the brain tissue effective stress, and the brain tissue displacement were obtained. The results indicate that, the intracranial fluid infiltration has a significant impact on the responses of the brain tissue under sustained high overloads. The present work emphasizes the appropriateness and necessity of using poroelastic constitutive models to describe the mechanical behavior of brain tissue, providing important theoretical insights for the study of brain biomechanics under extreme load conditions.

Although the brain is the most important organ in the human body, its thermo-mechanical coupling mechanism during cryogenic freezing remains unclear. A thermo-mechanical model for the cryogenic freezing of brain tissue was established, considering the special shape of the skull and brain, the cerebrospinal fluid, the cranial constraints, and the frost-heave effects. Analyses of the temperature field, the phase field, and the pressure field caused by the frost heave of the cerebrospinal fluid during freezing show that, the temperature of the cerebrospinal fluid remains unchanged during coagulation, while the maximum temperature difference within the brain tissue could reach 20 K. The solid-liquid phase interface is about 0.3 mm thick, and the driving velocity is about 0.09 mm/s. The maximum displacement of the brain tissue due to freezing is about 0.12 mm near the skull, and the pressure gradient at the solid-liquid interface is as high as 500 MPa/mm, while the pressure inside the solid and the CSF keeps almost unchanged. This study provides a theoretical support for the human brain cryopreservation strategy and the brain protection.

The epithelial-mesenchymal transition (EMT) is a critical step in physiological and pathological processes such as the embryonic development, the wound healing, and the cancer progression, wherein cells transition from a tightly adherent epithelial state to a dispersed mesenchymal state. An EMT core circuit model driven by the synergistic regulation of matrix stiffnesses and growth factors was proposed. The results show that, during the EMT, the matrix stiffnesses and growth factors collaboratively regulate the expression of the E/N-cadherin, a typical cell-cell adhesion molecule, by modulating the EMT-activating transcription factors, thus influencing the progression and reversibility of the EMT. The model elucidates the mechanism of synergistic interactions between mechanical and chemical factors on cell-cell adhesion during the EMT, laying a theoretical foundation for understanding the occurrence, development mechanisms, and preventive strategies against diseases such as cancer.

The ureteral pain caused by kidney stones has long tormented humans and seriously affected their quality of life. However, currently, in clinical practice, due to the lack of quantitative analysis of the interaction between kidney stones and ureters, urologists are unable to develop precise personalized treatment and pain relief plans for different patients. In response to this issue, small-sized kidney stones were taken as an example and to analyze the interaction behavior between small-sized kidney stones entering the ureteral lumen and the ureter with a fluid-structure coupling finite element method based on the coupled Eulerian-Lagrangian (CEL) algorithm. With the established ureteral pain model, the ureteral pain caused by small-sized kidney stones was quantitatively studied. The finite element analysis results indicate that, when the stone diameter is smaller than the inner diameter of the ureter, the stone will dynamically contact the ureter under peristalsis of the ureter wall, causing dynamic stress on the inner wall of the ureter. The stone moving speed will increase with the peristaltic amplitude of the ureteral wall, but the contacting probability between the stone and the ureter will decrease, and the contacting stress on the ureteral wall will decrease as well. The stress results were input into the ureteral pain model to calculate the corresponding central transmission neuron cell membrane potential. The model results show that, the change in the pain level over time was similar to the trend of dynamic stresses over time. In the case of alternating stress changes, the pain level would not decrease below the pain threshold as the stress drops to 0, showing inconformity between the pain level and the stress level. The results can be combined with existing medical imaging technologies in clinical practices, as well as big data and artificial intelligence technologies in the field of computer science. The research provides a theoretical basis for personalized and accurate diagnosis of the condition of stone patients, quantitative evaluation of patient pain levels, and the development of personalized treatment plans for precise medical clinical strategies.

The tissue remodeling is widespread in human tissues and organs, closely associated with morphogenesis, wound healing, fibrosis development, as well as cancer spread and metastasis. The mechanical microenvironment plays a crucial role in the tissue remodeling, yet the impact of tension regulation on wound remodeling remains unclear. A dynamic mathematical model for tissue remodeling induced by active cell contraction was established. The processes of lateral and inner wound remodeling in tissues with different pretensions were simulated with the finite element method. Additionally, the effects of tension regulation on wound remodeling were studied based on the model. The results show that, the tension regulation significantly influences the wound remodeling process, an appropriate tension reduction would effectively decrease the stress magnitude and the wound size. This study contributes to a deeper understanding of the mechanical effects in tissue remodeling and provides references for potential interventions in wound healing.

The fluid flow in the cartilage endplate (CEP) is the main path of nutrient supply and metabolic waste transport within the intervertebral disc (IVD). The increased stiffness, the decreased permeability and the water content of the degenerated cartilage endplate influence the mechanical responses and material transport within the IVD. A porous finite element model for C5-C6 of the cervical spine was established based on the computed tomography (CT) images of an adult. After validation, loads of compression, flexion, extension, axial rotation and lateral bending were applied to this model to calculate the instantaneous responses of the IVD. The calcification and sclerosis in the CEP were simulated with increase of its modulus and decrease of its permeability and porosity, compared with a healthy case. The results show that, the pore pressures within the CEP and the nucleus pulposus (NP) increase and the fluid velocity decrease in the degenerated CEP. Under flexion, the pore pressure in the NP increase by 50.8% and 88.9% in calcified and sclerotic CEPs compared to the healthy endplate, respectively. The decreases of the permeability and the water content in the degenerated CEP hinder the fluid flow and increase the maximum principal stresses of the NP matrix by 122.2% and 100.0% under compression and axial rotation, respectively.

An equal-strength cantilever beam sensor based on the multi-layer ionic skin (flexible capacitance sensor chips) was designed and prepared, to solve the problem that most existing thin-film-structure flexible sensors cannot simultaneously measure concentrated normal forces and displacements. The proposed sensor is comprised of the multi-layer ionic skin and the equal-strength cantilever beam. The normal contact forces or displacements can be acquired through measurement of the capacitance change of the sensor, with the free end of the beam contacting the measured object. A theoretical sensing model of the relationship between capacitance change and force/displacement was established and then verified through displacement/force loading tests. The test results show that, the sensing model is in good agreement with the test data. For the measurement of force and displacement, the sensitivity of the sensor with a 4-layer structure is 1.855 mN/pF and 0.694 mm/pF, respectively. The minimum measurable force is 0.02 mN and the minimum measurable displacement is 0.01 mm. At the same time, the sensor shows good linearity (R²=0.994). This sensing model provides a theoretical basis for the design of such sensors with good application prospects in the fields of flexible machines and medical health detection.

The ultrasound, as one of the non-invasive intervention or regulation measures in mechanotherapy, has attracted much attention. The methods, effects and action mechanisms of 4 types of ultrasounds for tissues/cells, namely, the high-frequency high-intensity ultrasound, the low-frequency high-intensity ultrasound, the low-frequency low-intensity ultrasound and the high-frequency low-intensity ultrasound were reviewed, and the emerging ultrasound therapeutic instrumentations were introduced. Then the future development trends of ultrasonic mechanotherapeutics were discussed. This review helps to promote the technical progress and clinical application of ultrasound mechanotherapy in tumor treatment, neurologic diseases (such as Alzheimer's disease and Parkinson's disease) treatment and so on.

The effectiveness of acupuncture therapy has been confirmed by numerous studies and incorporated into healthcare systems in many countries. However, the acupuncture therapy still faces some challenges, such as insufficient quantification of the acupuncture process, difficulties in inheriting acupuncture techniques, and inadequate accuracy in acupoint positioning. With the development of interdisciplinary integration in recent years, particularly the integration of engineering and medicine, new perspectives and methods have been proposed to address these challenges in acupuncture techniques. The historical development process of the core mechanical elements in acupuncture techniques was reviewed, including the mechanical stimulation tools (needles), the mechanical stimulation stages (insertion and manipulation stages), and the mechanical stimulation targets (acupoints). Through a comprehensive analysis of these 3 mechanical elements, their quantification and impacts on the acupuncture process and therapeutic effects were summarized. Meanwhile, relevant mechanical experiments and models conducted in quantitative acupuncture research were comprehensively recommended, to deepen the understanding of the acupuncture process. Then the cutting-edge research achievements in acupuncture robots were summed up, aimed to enhance the inheritance of acupuncture techniques and promote its international standardization process. Finally, this article outlines the future research direction of acupuncture mechanics.