Beat Sensor Research Articles

A GSM BASED INTELLIGENT WIRELESS MOBILE PATIENT MONITORING SYSTEM

Monitoring one’s heart rate and body temperature continuously from a remote area is impossible for a medical expert by using typical monitoring devices. To overcome this problem we can implement a GSM based system using microcontroller and LM35 sensor which is low-cost and use-friendly. Here, a heart beat sensor is used to detect the heart rate and an LM35 sensor to sense the body temperature. These signals are processed by a PIC microcontroller. Then, an SMS alert will be sent to the medical expert by using a GSM module. Thus, doctors can monitor the health condition of a patient continuously from a remote place and can suggest the patient about taking an immediate remedy. As a result, we can save many lives by providing them a quick service using this system.

Design and Development of a Heart Rate Variability Analyzer

Heart rate variability (HRV), analysis gives an insight into the state of the autonomic nervous system which modulates the cardiac activity. Here a digital signal controller based handy device is developed which acquires the beat to beat time interval, processes it using techniques based on non-linear dynamics, fractal time series analysis, and information theory. The technique employed, that can give reliable results by assessing heart beat signals fetched for a duration of a few minutes, is a huge advantage over the already existing methodologies of assessing cardiac health, those being dependant on the tedious task of acquiring Electro Cardio Gram(ECG) signals, which in turn requires the subject to lie down at a stretch for a couple of hours. The sensor used, relies on the technique of Photoplethysmography, rendering the whole approach as noninvasive. The device designed, calculates parameters like, Largest Lyapunov Exponent, Fractal dimension, Correlation Dimension, Approximate Entropy and α-slope of Poincare plots, which based on the range in which they fall, the cardiac health condition of the subject can be assessed to even the extend of predicting upcoming disorders. The design of heart beat sensor, the technique used in the acquisition of heart beat data, the relevant algorithm developed for the analysis purpose, are presented here.

General solution of undersampling frequency conversion and its optimization for parallel photodisplacement imaging

A general solution of undersampling frequency conversion and its optimization for parallel photodisplacement imaging is presented. Phase-modulated heterodyne interference light generated by a linear region of periodic displacement is captured by a charge-coupled device image sensor, in which the interference light is sampled at a sampling rate lower than the Nyquist frequency. The frequencies of the components of the light, such as the sideband and carrier (which include photodisplacement and topography information, respectively), are downconverted and sampled simultaneously based on the integration and sampling effects of the sensor. A general solution of frequency and amplitude in this downconversion is derived by Fourier analysis of the sampling procedure. The optimal frequency condition for the heterodyne beat signal, modulation signal, and sensor gate pulse is derived such that undesirable components are eliminated and each information component is converted into an orthogonal function, allowing each to be discretely reproduced from the Fourier coefficients. The optimal frequency parameters that maximize the sideband-to-carrier amplitude ratio are determined, theoretically demonstrating its high selectivity over 80 dB. Preliminary experiments demonstrate that this technique is capable of simultaneous imaging of reflectivity, topography, and photodisplacement for the detection of subsurface lattice defects at a speed corresponding to an acquisition time of only 0.26 s per 256 x 256 pixel area.

Practical realization of high-speed photodisplacement imaging by use of parallel excitation and parallel heterodyne detection: a numerical study.

A new parallel photodisplacement technique that achieves extremely high-throughput imaging is proposed, and its practical realization is studied numerically. In this technique, a linear region of photothermal displacement is excited by use of a line-focusing intensity-modulated laser beam and detected with a parallel heterodyne interferometer in which a charge-coupled device linear image sensor is used. Because of the integration and sampling effects of the sensor, the interference light is spatiotemporally multiplexed. To extract the photodisplacement component from the multiplexed sensor signal, a scheme of phase-shifting light integration under an undersampling condition is proposed for parallel interferometry. The frequencies of several control signals, including the heterodyne beat signal, modulation signal, and sensor gate signal, are optimized so as to eliminate undesirable components, allowing only the displacement component to be extracted. Preliminary numerical simulation results show that the proposed technique has the potential to perform photodisplacement imaging more than 10,000 times faster than conventional photoacoustic microscopy.