ABSTRACT
Ultrasensitive and sustainable near-infrared (NIR)-emitting piezoluminescence is observed from noncentrosymmetric and ferroelectric-phase Sr3 Sn2 O7 doped with rare earth Nd3+ ions. Sr3 Sn2 O7 :Nd3+ (SSN) with polar A21 am structure is demonstrated to emit piezoluminescence of wavelength of 800-1500 nm at microstrain levels, which is enhanced by the ferroelectrically polarized charges in the multipiezo material. These discoveries provide new research opportunities to study luminescence properties of multipiezo and piezo-photonic materials, and to explore their potential as novel ultrasensitive probes for deep-imaging of stress distributions in diverse materials and structures including artificial bone and other implanted structures (in vivo, in situ, etc).
ABSTRACT
This paper develops a portable measurement system for tissue strain distribution using ultrasonic pulse echo method. A single element ultrasonic transducer attached to a force sensor compresses biological tissue and observes the deformation process of the tissue. The center frequency of the ultrasound pulse is 3 MHz. The force applied to the tissue is kept at 10 N by an internal coil spring. Received echo signals are transferred to a personal computer via Universal Serial Bus. The developed measurement system was applied to measuring strain of subcutaneous fat for lymphedema patients and healthy subjects. The results quantified the fact that affected tissue becomes harder than unaffected tissue. Our experiment demonstrated that the system can be used for evaluating the condition of lymphedema with measurement of strain in subcutaneous tissue.
Subject(s)
Adipose Tissue/diagnostic imaging , Adipose Tissue/physiopathology , Diagnosis, Computer-Assisted/methods , Elasticity Imaging Techniques/methods , Lymphedema/diagnostic imaging , Lymphedema/physiopathology , Aged , Algorithms , Computer-Aided Design , Elastic Modulus , Equipment Design , Equipment Failure Analysis , Female , Humans , Middle Aged , Reproducibility of Results , Sensitivity and Specificity , Stress, MechanicalABSTRACT
This paper proposes a novel method to measure muscle movements for human interfaces. During muscle movements, cross-sectional muscle area changes, and this can be detected at the skin surface. In this study, a flexible piezoelectric thin film sensor is used to measure the morphological change of the skin surface. This sensor is made of oriented aluminum nitride (AlN) thin film, and the total thickness is less than 40 mum. Since the AlN film sensor has good sensitivity, small strain of the skin surface can be measured. Furthermore, a motion classification method is developed to investigate the potential of the proposed sensor for its use in human interfaces. Response characteristics of the AlN sensor were tested with experiments using a cantilever beam. In addition, motion classification experiments were conducted with five subjects, including a patient with cervical spine injury. The experimental results validate the effectiveness of the proposed method.
Subject(s)
Electrodes , Micro-Electrical-Mechanical Systems/instrumentation , Movement/physiology , Muscle Contraction/physiology , Muscle, Skeletal/physiology , Transducers , User-Computer Interface , Elastic Modulus , Equipment Design , Equipment Failure Analysis , Humans , Man-Machine Systems , Membranes, Artificial , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
Cardio-respiratory monitoring during sleep is one of the basic means for assessment of personal health, and has been widely used in diagnosis of sleep disorders. This paper proposes a novel method for non-invasive and unconstrained measurement of respiration and heartbeat during sleep. A flexible piezoelectric film sensor made of aluminum nitride (AlN) material is used in this study. This sensor measures pressure fluctuation due to respiration and heartbeat on the contact surface when a subject is lying on it. Since the AlN film sensor has good sensitivity, the pressure fluctuation measured can be further separated into signals corresponding to respiration and heartbeat, respectively. In the proposed method, the signal separation is achieved using an algorithm based on empirical mode decomposition (EMD). Experiments have been conducted with three subjects. The experimental results show that respiration and heartbeat signals can be successfully obtained with the proposed method.
Subject(s)
Electrocardiography/instrumentation , Heart Rate/physiology , Polysomnography/instrumentation , Respiratory Function Tests/instrumentation , Respiratory Mechanics/physiology , Transducers , Electrocardiography/methods , Equipment Design , Equipment Failure Analysis , Female , Humans , Male , Membranes, Artificial , Polysomnography/methods , Reproducibility of Results , Respiratory Function Tests/methods , Sensitivity and SpecificityABSTRACT
This paper proposes a compensation for a blurred image caused by misregistration in spatial compounding. The edge sharpening based on morphological operations is applied to the compounded image. A portable measuring system of a cross-sectional ultrasound image is designed for measuring body composition. The system is developed for non-medical applications, for example, measurement of the volume of muscle and subcutaneous fat in lower extremities, upper extremities and abdomen for health care and sports science. A number of partially overlapping images that have been obtained from multiple angles are combined into a single compounded image. In experiment on human abdomen, the image quality was improved in speckle suppression and edge enhancement by using ensemble averaging and morphological edge sharpening. Resulting wide field-of-view image was sufficiently deblurred without emphasizing noise.
Subject(s)
Abdomen/diagnostic imaging , Ultrasonics , Ultrasonography/instrumentation , Abdomen/pathology , Adipose Tissue/pathology , Algorithms , Equipment Design , Humans , Image Processing, Computer-Assisted , Models, Statistical , Models, Theoretical , Signal Processing, Computer-Assisted , Transducers , Ultrasonography/methodsABSTRACT
This paper proposes a new impedance estimation method for soft tissue using ultrasound. This method estimates the impedance distribution inside an object. An ultrasound probe, which is attached to a force sensor, compresses soft tissue and observes the deformation process of tissue while measuring reaction force. The impedance parameters are then estimated based on this information. Experiments were conducted under two conditions, a static analysis and a dynamic analysis. In the static analysis, the ultrasound probe compressed the soft tissue slowly while keeping a balance of the power. In the dynamic analysis, the probe compressed tissue dynamically, and the deformation process of the soft tissue was observed. Experimental results demonstrated that our method can estimate the impedance of a soft object.
Subject(s)
Algorithms , Connective Tissue/diagnostic imaging , Connective Tissue/physiology , Elasticity Imaging Techniques/methods , Image Interpretation, Computer-Assisted/methods , Models, Biological , Computer Simulation , Elasticity , Electric Impedance , Image Enhancement/methods , Reproducibility of Results , Sensitivity and Specificity , Stress, MechanicalABSTRACT
Ubiquitous echo is a portable ultrasound imaging equipment. We discuss an image sharpening method based on geometrical information by mathematical morphology with double structuring element (DSE) for on-line processing on ubiquitous echo. The sharpening method improves the contrast of tissue boundaries without speckle emphasis. The computational complexity of the morphological operations is reduced by chain rule of the operations and decomposition of the DSE not to delay refreshing the ultrasound moving image.
