Li Wang

Real-time mechanical monitoring of liquid-to-solid phase transitions is essential in materials science and biomedical diagnostics, yet existing instruments face challenges in continuously and nondestructively tracking the complete phase transition process of small-volume samples. Here we present an instrument for monitoring small-volume liquid-to-solid phase transitions based on magnetically driven droplet resonance. By combining phase-sensitive optical coherence tomography (OCT) detection with magnetic excitation using embedded superparamagnetic nanoparticles, the instrument enables continuous measurement of the resonance frequency throughout the entire transition process of a single 30 μ l droplet. We designed a sidewall-free sample base to confine the sample geometry via surface tension, providing consistent vibrational boundary conditions for cross-phase-state measurements. To mitigate electromagnetic interference-induced mechanical noise in the optical detection path under alternating magnetic fields, a non-metallic optomechanical structure was designed, reducing the displacement noise spectral density to below 3 nm Hz − 1 . The instrument achieves frequency measurement stability of ± 0.4 Hz and ± 0.6 Hz (15 min, standard deviation) for liquid and solid standard samples, respectively. Monitoring of agar gelation and porcine whole blood coagulation demonstrates the instrument’s ability to distinguish distinct phase transition mechanisms. This instrument provides a continuous, non-destructive mechanical monitoring tool for small-volume liquid-to-solid transition research and coagulation function assessment.

Assessment of coagulation function is crucial for anticoagulant therapy, surgical procedures, and cardiovascular diseases. Changes in the mechanical properties during coagulation can directly reflect coagulation function. Here, we report a magneto-droplet resonance spectroscopy (MDRS) method to monitor the mechanical property changes of a single drop sample (30 μL) as it transitions from a liquid state to a clot. We utilized a series of low-mass-fraction agarose gel solutions to mimic blood samples with varying coagulation characteristics. We obtained the changes in the resonance frequency of the sample during coagulation and calculated Young's modulus of the coagulated sample using a multi-degree-of-freedom model. The results demonstrate that this method can monitor the whole coagulation process of a single drop sample and effectively distinguish samples with Young's moduli ranging from 0.36 to 2.00 kPa. The MDRS method has the potential to serve as a highly sensitive tool for monitoring the coagulation function of small-sized blood samples.

The electrolarynx (EL) is a common device for voice reconstruction in laryngectomy patients, but its mechanical sound source generates significant radiation noise, affecting the naturalness and acceptability of the speech. The parametric acoustic array (PAA), which produces directionally propagated difference-frequency sound waves, presents a promising alternative for creating a more natural glottal-like voice source in the trachea while reducing radiation noise. In this study, we developed a tissue-mimicking phantom to simulate human neck tissue and used a single-transducer-based PAA platform to generate modulated ultrasound signals with glottal waveform characteristics. Ultrasonic microphones captured sound signals fromthe trachea and surrounding air, and signal processing was used to isolate the difference-frequency signals. The results demonstrated that difference-frequency signals were successfully detected in the phantom’s trachea, with time-domain waveforms and frequency spectra closely resembling the designed glottal waveform (Pearson correlation coefficient = 0.9438). Additionally, radiation noise produced by the PAA was significantly lower (23 dB, p < 0.0001) compared to the traditional EL. These findings demonstrate the potential of PAA for voice source reconstruction in laryngectomy patients and suggest its capacity to enhance speech rehabilitation outcomes. Further research is required to refine the frequency range and evaluate clinical applicability.

Dynamic curved interfaces are fundamental and ubiquitous structures in biological systems. However, replicating the structure and function associated with these interfaces for mechanobiology and drug screening is challenging. Here, we develop a dynamic curvature-enabled microfluidic organ chip of two fluid–solid dynamic curved interfaces. One interface effectively integrates adjustable biomechanics, and the other controls drug release with open microfluidics. The fluid–solid interface sensed by the cells can modulate the residual stress, stiffness, strain of the solid phase, and the flow shear stress of the fluid phase. Using the chip, we investigate the mechanotransductive responses of endothelial and epithelial cells, including Piezo1, Ca2+, and YAP, and reveal that the response of the endothelium to combined dynamic cyclic strain and flow shear stress is different from separate stimulation and also disparate from the epithelium. Furthermore, direct and high-efficiency drug release to cells is realized by constructing the other fluid–solid interface on the back side of cells, where drugs are encapsulated within cross-linked alginate hydrogel in the open microfluidic channel. Then, we replicate object-specific and location-specific biomechanical environments within carotid bifurcation and prove the effectiveness of drug delivery. Our design exemplifies dynamic curved biological interfaces with controlled mechanical environments and holds potential for patient-specific medicine.

Gait abnormalities are common in patients with chronic vestibular syndrome (CVS). Accurate evaluation of the degree of instability in CVS patients is of great clinical significance for the diagnosis and treatment of CVS. The objective of this study was to explore the accuracy, specificity and sensitivity of dynamic stability analysis and conventional kinematic analysis to assess the degree of instability in chronic vestibular syndrome. 16 CVS subjects were graded with DHI scale as the gold standard. The kinematic data of the subjects were collected using a 3D motion capture system. The conventional kinematics parameters such as sagittal, coronal and 2-D body center of mass (COM) velocity and acceleration, and the dynamic stability parameters such as sagittal, coronal and 2-D velocity stability domain are calculated. Finally, the accuracy, specificity and sensitivity of different analysis methods in evaluating the degree of instability in CVS patients were carried out. For CVS patients and controls, the maximum sensitivity, specificity and accuracy of COM velocity or acceleration peak were 75.0%, 93.7% and 90.2%, respectively, while the corresponding indexes of two-dimensional velocity stability domain parameters were 100.0%. For patients with mild CVS disorder and patients with moderate CVS disorder, the sensitivity, specificity and accuracy of COM velocity or acceleration peak can reach up to 87.5%, 50.0% and 40.6%, respectively, and the two-dimensional velocity stability domain parameters can reach 100.0%, 75.0% and 73.4%, respectively. The sensitivity, specificity and accuracy of 2-D velocity stability region and COM acceleration peak comprehensive evaluation are improved to 100.0%, 87.5% and 100.0%, respectively. In terms of sensitivity, specificity and accuracy of evaluating the degree of gait instability in patients with CVS, the two-dimensional velocity stability domain parameters are better than the traditional kinematics parameters. Dynamic stability parameters can be used to quantitatively describe the difference of dynamic stability during walking between CVS patients and control subjects of different degrees. This study can provide reference for the subsequent quantitative evaluation of gait stability in patients with CVS.

Objective: Extracorporeal shock wave therapy (ESWT) has been widely used in clinical and rehabilitation fields. However, limited knowledge of shock wave sources constrains its therapeutic efficacy. This study aimed to simulate and analyze the characteristics of shock wave sources generated by the radial extracorporeal shock wave therapy (rESWT) device at different media interfaces. Methods: In this paper, a numerical calculation model including the front portion of the handpiece of an rESWT device and three different media (soft tissue, water, and air) was established using the finite element method, and the dynamic impact process was carried out according to the basic principle of the rESWT apparatus. The projectile speed was set to be 7.11, 12.46, 17.81 and 23.16m/s, respectively. In addition, the waveforms at the geometric center of the applicator surface were extracted, and the temporal and spectral characteristics of the shock wave source were disclosed. Results: The waveform of shock wave generated by the applicator of the rESWT device at soft tissue and water interface were similar at the same projectile speed, but both being different from the waveform at air interface. The absolute positive and negative pressure values at the air interface were three orders smaller than those observed at the soft tissue and water interfaces. The spectral characteristics of the waveforms at different media interfaces were similar, with modulation frequencies of soft tissue, water and air being 4.51 kHz, 3.97 kHz and 4.03 kHz, and carrier frequencies being 78.00 kHz, 76.90 kHz and 77.27 kHz, respectively. At different projectile speeds, there was no variation in the waveform shapes of the same medium, revealing that the projectile speed didn't affect the peak frequency of the shock wave waveform. The projectile speed only affected the amplitude of the shock wave waveform, indicating that the absolute positive and negative pressure at the medium interface increased linearly with the projectile speed. Conclusion: The shock waves produced at various media interfaces displayed changes in their temporal and spectral characteristics, and the results observed in biological soft tissues couldn't be directly substituted with those observed in air or water. The findings could offer crucial insights into the assessment of rESWT devices and the enhancement of clinical shock wave treatment protocols.

Extracorporeal shock wave therapy (ESWT), a non-invasive clinical approach, is widely used in sports rehabilitation, orthopaedics, and aesthetic medicine, whose treatment effects result from the interaction of mechanical impulsive waves with target tissues. Though generally accepted, the nature of waves generated by ESWT is not clearly disclosed when propagating through tissues, resulting in the limitation of the technique. In this work, propagation characteristics of shock waves within the tissue-mimicking phantom are revealed. Our approach involves employing a thin, flexible PVDF sensor embedded within the phantoms to capture dynamic wave pressure signals. These signals facilitate the extraction of pertinent features across various impact pressures and depths. Our results demonstrate that the impulsive wave's rise time approximates 5μs. It produces a positive pressure peak ranging from 0.5 to 8.2 MPa, and a negative pressure peak from -0.19 to -3.28 MPa. Notably, peak amplitudes decrease with increasing depth while maintaining a constant impact pressure. As driving pressure increased, maximum positive pressure increased linearly at the same depth. The implications of our findings are pivotal for the design of pertinent devices, formulation of treatment strategies, and assessment of treatment efficacy. Ultimately, a comprehensive understanding of shock wave propagation will enable more informed and effective applications of ESWT.

An electrolarynx (EL) is one of the most popular voice rehabilitation technologies used after laryngectomy. However, most ELs generate monotonic EL speech, which has been shown to create a particular deficit in speech intelligibility, especially for Chinese Mandarin (Mandarin). Mandarin is a tonal language that makes lexical distinctions using variations in tone. Our purpose is to design an EL that can produce the four Mandarin tones, and to evaluate its performance. We designed a fundamental frequency (F0) control method for Mandarin EL speech and manufactured a touch-controlled electrolarynx (T-EL) prototype. Using monosyllables, disyllabic words, and frequently used phrases, we evaluated speech produced with a T-EL, as well as with monotone (M-EL) and variable-frequency modes (P-EL) of a commercially available TruTone EL. A male native Mandarin speaker with laryngectomy volunteered to be the speaker. Results show that the normal speech pitch contours of the four Mandarin tones were most closely matched by the characteristics produced with T-EL. The statistical accuracy of the T-EL's tone and word perception was significantly higher than that of the other EL types. Moreover, the confusion matrix indicates that the listeners could correctly identify the tones of monosyllables and disyllabic words in T-EL speech. Accurate tone judgment can improve the intelligibility of EL speech in Mandarin. The mean opinion score was used to evaluate the listeners' acceptability of EL speech. The scores of the T-EL and M-EL were very close, and the score of the P-EL was significantly lower than that of the other two ELs. However, the results from a single speaker cannot provide sufficient data to conclude which EL has a higher acceptability. The evaluation of multiple EL speakers with different EL types at difference levels of proficiency should be studied in future research.