Method and apparatus to measure bodily fluid and its change, and blood volume change
A method of calculating body fluid and blood flow in a human or animal body using multi-frequencies alternating electrical currents, determining the tissues' multi-frequency impedance and reactance changes, calculating the body fluid, blood flow and physiological parameter. With the simultaneous measurements of body's or tissues' impedance and reactance from multi-frequencies, it is possible either to compensate for the frequency-dependencies or to find the dependencies' cross relationship, and thus measure body fluid and blood flow more accurately.
1. A method to measure bodily fluid parameters, blood flow parameters and physiological parameters, the method comprising:
summing multiple signals of different frequencies, synchronously aligning them on complete cycles of all frequencies and turning them into a digital sequence;
converting the digital sequence into multiple alternating currents, and transmitting the multiple alternating currents within a same time period;
injecting said multiple alternating currents as injecting signals into a human or animal body through electrodes and forming an injection loop with external electrical parts to produce modulated multiple alternating currents;
overlapping a receiving loop partially with the injection loop to sample the modulated multiple alternating currents as sampled electrical signals;
segmenting the sampled electrical signals into the same time period as that of transmitted sequences;
synchronizing the sampled electrical signals with said transmitted sequences;
demodulating the sampled electrical signals, and subtracting said injecting signals to produce final signals;
processing the final signals to calculate the bodily fluid parameters, blood flow parameters and/or physiological parameters from the multiple signals of different frequencies.
2. The method according to claim 1 , wherein the summing is achieved by summing multiple signals of different frequencies in a frequency domain and synchronously turning the multiple signals of different frequencies into the digital sequence, the summing further comprising: summing the multiple signals of different frequencies in the frequency domain and synchronously turning the multiple signals of different frequencies into the digital sequence in a time domain on all complete sinusoidal cycles of different frequencies using an Inverse Fast Fourier Transform (IFFT).
3. The method according to claim 2 , wherein the converting comprises passing the digital sequence through a Digital-to-Analog Converter (DAC) having clock rates from 100 KHz to 10 MHz.
4. The method according to claim 3 , wherein the summing comprises upconverting the digital sequence into a longer sequence, but transmitting within the same time period.
5. The method according to claim 3 , wherein when the modulated multiple alternating currents are passing through the human or animal body, they are modulated by blood and tissues within the human or animal body.
6. The method according to claim 3 , further comprising analog-to-digital converting of the sampled electrical signals using a conversion rate between 100 KHz and 2.5 MHz.
7. The method according to claim 2 , wherein the summing comprises upconverting the digital sequence into a longer sequence, but transmitting within the same time period.
8. The method according to claim 2 , wherein when the modulated multiple alternating currents are passing through the human or animal body, they are modulated by blood and tissues within the human or animal body.
9. The method according to claim 1 , wherein the summing comprises upconverting the digital sequence into a longer sequence, but transmitting within the same time period.
10. The method according to claim 9 , wherein when the modulated multiple alternating currents are passing through the human or animal body, they are modulated by blood and tissues within the human or animal body.
11. The method according to claim 1 , wherein when the modulated multiple alternating currents are passing through the human or animal body, they are modulated by blood and tissues within the human or animal body.
12. The method according to claim 11 , further comprising extracting related information to perform the processing, wherein the related information comprises the human or animal body's impedance changes in amplitude and phase along a frequency range from 10 KHz to 1 MHz.
13. The method according to claim 12 , further comprising monitoring states of the human or animal body using the calculated bodily fluid parameters, blood flow parameters and/or physiological parameters.
14. The method according to claim 1 , wherein, after the overlapping, the method further comprises amplifying the detected sampled electrical signals and analog-to-digital converting the detected sampled electrical signals into digital signals.
15. The method according to claim 1 , wherein the demodulating the sampled electrical signals further comprises, after subtracting the injecting signals from the sampled electrical signals to yield subtracted signals, subtracting system amplitude and phase responses from the subtracted signals.
16. A system for implementing the method of claim 1 , wherein the system comprises a signal generator, a signal detector, and a signal processor;
the signal generator to generate the multiple signals of different frequencies and perform the summing and converting;
the signal detector to perform the injecting and overlapping to amplify collected bio-signals through wires or cables to produce the sampled electrical signals;
the signal processor to perform the segmenting, synchronizing, demodulating, and processing to extract bio-information from the final signals to calculate the bodily fluid parameters, blood flow parameters and/or the physiological parameters.