Mixtures of colloids with different sizes or shapes are ubiquitous in nature and extensively applied in industries. Phase transition pathways and kinetics in this model system should be investigated because of the difficulty in observing tri-phase coexistence in colloidal platelet-sphere mixtures. Similar to the polymer-sphere mixtures, the phase transition pathway has three main categories. Analytical results show a staged phase transition process in which the mixture first separates into one or two metastable phases, then further separates, and subsequently reaches tri-phase equilibrium. Unique to our system, and different from the gas-liquid-crystal coexistence in colloid-polymer mixtures, the platelet-sphere mixture reached a gas-liquid-liquid crystal (nematic) coexistence. Thus, the different phases are easy to distinguish using the birefringence of the liquid crystals. In addition, the volume fraction of the liquid crystal formation in the ZrP platelet suspensions is much lower than for the crystal formation in hard spheres.

Purpose The purpose of this paper is to design a smart handheld device with force regulating function, which demonstrates the concept of patient-specialized tools. Design/methodology/approach This handheld device integrates an electrical bioimpedance (EBI) sensor for tissue measurement and a constant force regulation mechanism for ensuring stable tool–tissue contact. Particular focuses in this study are on the design of the constant force regulation mechanism whose design process is through genetic algorithm optimization and finite element simulation. In addition, the output force can be changed to the desired value by adjusting the cross-sectional area of the generated spring. Findings The following two specific applications based on ex vivo tissues are used for evaluating the designed device. One is in terms of safety of interaction with delicate tissue while the other is for compensating involuntary tissue motion. The results of both examples show that the handheld device is able to provide an output force with a small standard deviation. Originality/value In this paper, a handheld device with force regulation mechanism is designed for specific patients based on the genetic algorithm optimization and finite element simulation. The device can maintain a steady and safe interaction force during the EBI measurement on fragile tissues or moving tissues, to improve the sensing accuracy and to avoid tissue damage. Such functions of the proposed device are evaluated through a series of experiments and the device is demonstrated to be effective.

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In general, the electrical property of soft tissues is sensitive to the force applied to their surface. To further study the relationship between the force and the electrical property of soft tissues, this paper attempts to investigate the effect of static and higher-order stresses on electrical properties. Overall, a practical experimental platform is designed to acquire the force information and the electrical property of soft tissues during a contact procedure, which is featured different compression stimuli, such as constant pressing force, constant pressing speed, and step-force compression, etc. Furthermore, the piezoresistive characteristic is innovatively introduced to model the mechanical-electrical properties of soft tissue. Finite Element Modeling (FEM) is adopted to fit the static piezoresistivity of the soft tissue. Finally, experimental studies were performed to demonstrate the effect of stress on the electrical properties and the feasibility of the proposed piezoresistive model to describe soft tissues’ mechanical and electrical properties.