FR2894805A1 - INTEGRATED SYSTEM FOR THE COLLECTION AND ELECTRIC STIMULATION OF CELLULAR ELECTROPHYSIOLOGICAL ACTIVITIES OF DEEP ORGANIC STRUCTURES - Google Patents

Abstract

The present invention relates to an integrated system for the collection and electrical stimulation of cellular electrophysiological activities of deep organic structures and / or surfaces, comprising means for acquiring an electrical signal of cellular origin, characterized in that it furthermore comprises means for transmitting data to a data storage and analysis system, by developing improved telemetry using the WLAN and HiperLAN systems, and in that it comprises analysis means real-time data through software coupled to the recording system, a suitable electrical signal being sent back; the latter also being transmitted by the same wireless link and allowing direct action on the structure being explored or monitored.

Description

INTEGRATED SYSTEM FOR COLLECTING AND STIMULATING ELECTRIC ACTIVITIES

  BACKGROUND OF THE INVENTION The present invention relates to the field of information and communication technologies. The present invention relates more particularly to an integrated system for the collection and electrical stimulation of cellular electrophysiological activities of deep organic structures.

  The present invention comprises two aspects: an instrument for measuring physiological signals of 15 deep and surface structures; a "full duplex" wireless transmission system based on wireless networks of WLAN, HIPERLAN, UWB, .. .

  In animal medicine and biology, the collection of cellular activity-related electrical signals produced by different body structures necessitates the use of sensors connected to amplifiers. These two elements of the acquisition chain are interconnected by connector wires of variable lengths, often from a few tens of centimeters to more than one meter. These electrical signals are used to diagnose or monitor the functional state of the organ being explored. Data analysis may lead the physician or researcher to act based on the observations made. The system according to the present invention incorporates a number of elements essential to the acquisition of the cellular electrical signal, transmits data to a data storage and analysis system, by the development of a new telemetry generation using WLAN and HiperLAN systems. After analysis of the real-time data by the torque software in the recording system, a suitable electrical signal is returned. The latter is also transmitted by the same wireless link and allows a direct action on the structure being explored or monitored.

  The present invention allows the exploration of several subjects (persons and / or animals) in the same place, the number and nature of the signals are not limited. To do this, techniques derived from standards governing wireless networks for frequencies from 2GHz to 10GHz are used, the latter value not being a limit. The invention can be used in all fields where the lion needs to transmit many signals with low spectral space (medicine, airport, home automation, control of industrial processes, ...).

  In what follows, the party that collects the signals will be called transceiver (transmitter / receiver) and the party that captures the signals emitted by the tranceiver will be named point 20 access. The latter plays the role of server and manages access to the transmission channel or medium.

  The prior art already knows, from US patent application 2004/0015058 (Motorola), equipment for wireless medical diagnosis and monitoring. This equipment has wireless electrodes that are attached to the surface of the patient's skin. The electrodes comprise a digital transmission and reception unit with antenna and micro-sensors. The electrodes can be used, inter alia, for de-teetering EEG and ECG signals, but also for observing body / breathing movements, temperature, perspiration, etc. A preferred embodiment comprises an electrode having all the functions of a semiconductor chip, which, as an integrated circuit, is equipped with a sensor, a sensor control unit, a frequency generation unit, ds transmission and reception, as well as a transmission control unit. The antenna is arranged in the flexible electrode, covering the chip or directly in the chip.

  The present invention intends to overcome the disadvantages of the prior art by proposing an integrated system comprising data transmission means to a data storage and analysis system, by developing an improved telemetry using WLAN and HiperLAN systems. .

  To this end, the present invention relates, in its most general sense, to an integrated system for the collection and electrical stimulation of cellular electrophysiological activities of deep organic structures, comprising means for acquiring an electrical signal of cellular origin. , further comprising means for transmitting data to a data storage and analysis system, developing improved telemetry using WLAN and HiperLAN systems, and comprising means for analyzing the data in real time by means of software coupled to the recording system, a suitable electrical signal being sent back; the latter is also transmitted by the same wireless link and allows direct action on the structure being explored or monitored.

  The measuring instrument: The first aspect of the present invention consists in producing a medical measuring instrument for the collection and electrical stimulation of cellular electrophysiological activity of deep organic structures. It can also perform the acquisition of biological signals such as the EEG (ElectroEncephaloGramme), the EMG (ElectroMyoGramme), the ECG (ElectroCardioGramme), the arterial pressure relay, ... This instrument with implantable sensors and / or surface, can be used for any physiological analysis such as: • the detection of more or less deep cellular potentials, • sleep, • heart rate, • blood pressure, • epilepsy, 15 • muscle movements • eye movements, ... in humans for clinical research and analysis and in animals for basic research. It can also be used to monitor the evolution of a physiological signal (eg epilepsy) or to stimulate certain structures for therapeutic purposes such as in Parkinson's disease for example. The wireless transmission system: The second aspect of the present invention relates to a telemetry device for transmitting biological signals by radio frequency (RF) waves operating in a frequency band specific to ISM, UNII, 802.16, applications. ..

  The principle of the present invention utilizes the fundamentals of wireless network communication protocols dedicated to few immobile peripherals that require large bandwidth. In contrast, we use our network with many devices that can be slightly mobile but need a very low bandwidth (500Hz to 10kHz). In our case, a device is a system in humans and animals. o equipped with 1 or more sensors by transceiver, o 1 or more devices that can be connected to the same subject. Arrangement of the two parts: The telemetry device is integrated in the measuring instrument and communicates with a control station (a computer for the visual analysis of the biological signals). The set formed by the measuring system and telemetry system does not require any additional device to communicate with the remote control station. Only software is needed on the latter for viewing and controlling the signal measurement parameters. The control station has a wireless connection through an access point.

  The transceiver is easily concealable since it benefits from the latest advances in microelectronic integration. Platform of the invention

  The present patent application covers virtually all the possibilities and solutions for achieving a medical measuring instrument and wireless transmitter for the collection and electrical stimulation of cellular electrophysiological activity of deep organic structures. It can also perform the acquisition of biological signals such as EEG (ElectroEncephaloGram), EMG (ElectroMyoGram), ECG (ElectroCardioGram), arterial pressure relay, ...

  The physiological signals as they present themselves can not be directly exploited, given their small amplitude which varies from the microvolt to about ten millivolts. Therefore a system of acquisition / amplification is necessary to make them observable to the practitioner.

  In practice, after being collected by a sensor, the signal must be amplified (variable gain from 100 to 1000000), • low and high frequency spurious signal filter (high-pass and low-pass filters with variable cut-off frequency) , • digitize (the number of bits is> -4 without the upper limit), • code (any baseband coding may use), • compresses (all coding techniques may be implemented, including coding spouse), • formatted (constitution of a frame that is our own), • module (the modulations used are those defined in the software layers of wireless networks), • '• transmitted over the air (in accordance with the standards in force, 802.11, 802.16, ...). The control station performs after reception via the access point, the reverse operations and displays on a screen the appearance of the signals collected. A tranceiver can group several sensors of different kinds or not, but it can also have only one sensor. Whatever the number, a sensor is either surface or deep, that is to say within physiological structures. A transceiver can have sensors both surface and / or depth.

  The link between the transceiver and the access point is "full duplex", which allows a complete management by the control station - the communication protocol, - the standby or the activation of a transceiver, for each transceiver: 15 o the gains, o the sampling, o the bandwidth, o the transmission times, o the nature of the transmission (pulse or continuous), but also the sending - more or less complex stimuli of physiological structures.

  We use the communication protocols of wireless networks, governed by the standards in force 8021.11, 802.16, ..., to transmit signals having a very low spectral space.

  The transmission protocol complies with the standards in force and will adapt to future standards in order to always offer the highest flow rate. The communication frequencies are those defined for wireless applications operating at least 2 GHz, examples of networks to date, WLAN, HIPERLAN, 35 UWB. But the invention can adapt to any new standard.

  The appropriate access mode for our transmission is based on the permanent listening of the medium (transmission channel) of any connection point (transceiver). Thus, the collisions are avoided (CSMA / CA for example) and by using mechanisms of medium reservation (RTS \ CTS, for example) and mechanisms of acknowledgments, each transceiver can transmit data by calculating a random delay (algorithm uses in Ethernet frames).

  When collisions are not avoided (loss of information), the physical layer uses the FEC (Forward Error Correction) mechanism based on sending a duplicate data. Coding may also be implemented, such as for example Huffman, Hamming or Reed Solomon encodings, or any other suitable coding.

  This mode was chosen after a theoretical study describing the different transmission standards and their feasibility to transmit biological data. It was valid on a real transmission of EEG signals that used WIFI equipment for the general public.

  The physical layer of the standards we use provides us with a variety of transmission types that vary flow and power according to the environment in order to maintain communication in as many configurations as possible. To do this, all the known and future digital modulations for RF transmission can be used (examples: DBPSK, DQPSK, QAM). Thus the bit rate may vary according to modulation to suit the environment. It is also possible to remedy the channel fading problem using techniques such as spectrum spread (barker code and CCK) or OFDM found in the CDMA access mode (which uses the same principle that barker and CCK codes) are used in GSM and EDGE.

  Note that the modulations of the different standards are very close, therefore the migration to one or the other or to a future standard is very fast.

  The MAC layer of the network offers an error control mechanism (CRC) for verifying the integrity of the frames. The access point • plays the role of the server, • manages access to the medium, • controls the transmission power of the transceiver, • sends control bursts to each connected transceiver in order to avoid a simultaneous transmission of two transceivers .

  We use the physical, software and MAC layers of current or future standards. That being to achieve our ends, we develop our own coding and our own frames.

  The invention will be better understood with the aid of the following description, given purely for explanatory purposes, of an embodiment of the invention, with reference to the appended figures. FIG. 1 is a diagram of the transmitter-receiver (FIG. transceiver) and the access point; Figure 2 shows the frame used in detail; Figure 3 illustrates the frame in the animal; And Figure 4 illustrates the frame in humans.

  The transceiver is composed of the different parts shown in Fig. 1. The signals pass from the transceiver to the access point 100: It is the sensor that converts our physical quantity into a signal electric that can be processed by the transmitter. It is either placed on the surface of the body or introduced deep into the cellular tissues.

  It satisfies the following constraints: • it has a very high sensitivity to the signal to be measured, • it is biocompatible and sterilizable, • it is designed in such a way as to disturb the signal, • it has reliable and stable characteristics: recording area , impedance, stainless.

  The impedance of the sensors used in the system according to the present invention varies from a few kΩ to several MO depending on their type. 101: The sensor 100 is directly connected to one of the differential inputs which is a very low noise preamplifier. The pre-amplification is done in differential mode, either between two active sensors, or between an active sensor and a reference. The input noise level of the preamplifier is at least less than the tenth of the weakest signal that can be collected in electrophysiology.

  The amplitude must go from a few microvolts to a few millivolts. The common mode rejection rate (TRMC), which also defines the ratio of the differential mode gain to the common mode gain, must be as high as possible and is a primary criterion in the choice of the preamplifier. 102 and 103: The output of the preamplifier 101 is directly connected to a bandpass filter which may or may not be divided into two filters: a high pass filter 102 and a low pass filter 103. These elements allow the adjustment and selection of a frequency band of the specific signal. This is a solution to the problem of noise from the environment and other biological signals. The high pass filter eliminates the offset voltage from the preamplifier well over the entire BF. Its lower limit is given by the spectral content at low frequency of the signal collected. The low pass filter allows to eliminate all the HF, its upper limit is given by the high frequency spectral content of the collected signal. Although these cut-off frequencies are programmable, it is preferable to set for the main application according to the invention a bandwidth of 3 Hz to 10 kHz.

  105: the output of the low-pass filter 103 is connected to the input of a low-noise amplifier with adjustable adjustable gain, the gain control is done digitally from the remote control station.

  106: It's a processor in the broad sense of the word. It manages the bidirectional communication, controls the active components (101, 102, 103, 104, 107, 108, 109) and the synchronization between the different tasks performed on the transmitter board as well as the data backup in the mass memory and Sending the wireless communication frame. This sending can be continuous or pulse.

  It includes a rewritable program memory, even in run mode, a data memory as well as an analog / digital converter. The sampler is integrated or not in the processor. It can work at a frequency of 20 kHz, the selection of the sampling frequency is done remotely from the control station.

  Once the data has been digitized, the processor 106 adds to each data item the identifier code of the sensor concerned according to the coding techniques known in the digital transmissions. Any code is eligible, especially if it allows the compression of data and / or the joint coding. Finally, the processor provides the frame containing the data to be transmitted to the access point.

  107: the frame sent by 106 is transmitted according to a standard in force by the element 107 also having a processor. Serial or parallel communication is established between the two entities 106 and 107 to synchronize the two processors. 107 adds to this frame the preamble and the heading used in the standard. The complete frame thus formed is bleached, using a pseudo-random sequence, and then mapped by the modulation for the object (DBPSK for example) and the preamble is coded (eg barker) to achieve the largest possible flow. The data is mapped according to the desired dynamic flow rate, which depends on the environment, then it is coded (barker or CCK for example). Then, a digital-to-analog converter, whether integrated in the 107 or not, makes the analog output signal. An electronic switch (switch), allows the choice of a standard (802.11g, 802.11a, for example).

  108: This element transforms an asymmetric signal into a symmetric signal at the I and Q outputs. This differential signal is connected to the modulator 109.

  109: It is a modulator that raises the signals of 109 on a carrier frequency defined by the chosen norm. The propagation channel is selected here according to the information transmitted by the element 106.

  110: the output of the 109 is differential, it 5 becomes asymmetrical thanks to the balun 110.

  111: it is a filter which respects the condition of Nyquist, and which makes it possible to limit the spectrum of the signal out of 110 in order to avoid the inter-symbol interferences.

  112: The signal thus filtered by 111 is then amplified by respecting the maximum power defined in the standard used.

  113: This is an integrated antenna or not, used to send and receive the signals of 114. This element deserves a particular attention because it contributes strongly to the level of reception and / or of the mission of the signal, which is essential for remedy the fading problem (Fading).

  114: The access point receives and & waves. In reception, it converts them into digital data ready to be processed by the control station 115, in transmission, it performs the same operations as those seen previously.

  115: An interface allows from the control station 115 to view and analyze the signals received from each transceiver. Software for medical applications can be used. The signals flow from the access point to the transceiver 14 115: A man / machine interface gives the possibility of sending commands from the access point to all the tranceiver, examples: • the change of gain, • the change of frequency sampling, • the selection of the frequency band of the signal to be analyzed, • the sending of stimulations, ...

  The control frame is made from this interface and then sent to 114 which converts it into a frame respecting the mandatory parts that the chosen standard imposes. The process of bringing the signal to the antenna of the access point is identical to that described above. 116: After reception by the antenna 113, if the message is intended for this transceiver, the RF signal passes through a low-noise amplifier 116. 11 then takes the opposite path from that previously described, namely: • the bandpass filter 111 eliminates the BF and the HF at the output of 116, the balum 110 transmits a symmetrical signal at 109, the RF signal is debarred from its carrier at 108, it is demodulated and decodes at 107, a serial synchronization link or parallel between 107 and 116 makes possible the extraction of data, the command is then identified, for example: o a sensor impedance test, o a change of gain, o a change of frequency, o a bandwidth change, o a data acquisition launch, o a biological zone stimulation via a sensor, 35 Once the action (s) has been completed, the transceiver is again ready to transmit or receive information. Other Circuits 117: A guard circuit connects the transceiver to the sensor shield to counteract the common mode voltage of 100 which alters the sensed signal.

  118: Equipotentiality or reference of the subject to the mass of the system can be provided in a variety of ways: • by a conventional DRL circuit, • by grounded sensors on each transceiver, 15 by a signal reference signal transmitted by the access point to each transceiver, • by an average signal of all the signals being acquired, • by any means making it possible to make a neutral point relative to the measurement in progress. The transmission frame: The transmission protocol used in the present invention complies with the standards in force but changes some parameters concerning in particular the data frame. In authorized locations, additional information is passed over biological data. In the animal. The system according to the present invention makes it possible to study several groups (IDGR) of several animals (IDAN), each animal having several sensors (CAPi). We will have at least the information represented in Figure 3.

  With: • Gi sensor gain i, sampling frequency, acquisition start time, acquisition end time, • Nbrcap, the number of active sensors, • Scapi, data collected on the sensor ia to, to + (1 / fo), ... until t1.

  To this must be added the identification bursts of each sensor plus those of control and control of the access point which remain unchanged. The studies of the inventors show that we can at least consider 10 sensors by transceiver. Each animal will be equipped with a tranceiver, we will be able to analyze at least 12 animals per group and at least 16 groups simultaneously. That is, a minimum capacity of 19,200 signals for basic research. In humans The system according to the present invention makes it possible to study several persons (IDPA) with several transceivers (IDTR), each transceiver having several sensors (CAPi). We will have at least the information represented in Figure 4.

  30 With: • Gi sensor gain i, • fo, sampling frequency, • to, acquisition start time, • t1, acquisition end time, 35 • Nbrcap, the number of sensors • Scapi, the data collected on the sensor ia to, to + (1 / fo), ... up to t1.

  To this must be added the identification bursts of each sensor, plus those of control and control of the access point which remain unchanged.

  In humans, for clinical research, we will have a tranceiver for each group of sensors, ie at least 12 transceiver in the case of an EEG for example. Here, it is therefore the IDPA parameter which will have to be important if one wishes to make measurements on several patients simultaneously.

  Whether in humans or animals, parameter frames are sent from the access point to each transceiver to initiate the measurements. The times t0 and t1 make it possible to synchronize the signals on the control station and in case of loss of a frame, not to offset the information received. For the size of the wanted frame, cosimulation tests and practices will be performed to determine the optimal size of the frame to be sent because the probability of a loss of a long frame is greater. On the other hand, a collision is less likely in the case of two long frames. 25 Knowing that the size of the frame is between 6 and 2312 bytes.

  Mode of Access: Three transmission phases are respected: that of identification (authentication), transmission (actual transmission of data) and disconnection. 18

  The authentication frame (burst) makes it possible to establish the connection between each transceiver and the access point, this operation is necessary for the synchronization between the entities of the wireless network. This burst meets the standard used.

  The access point broadcasts regularly (at the rate of sending every 0.1 second or so) a beacon frame (named beacon) giving: • information about the BSSID, • its characteristics • possibly its ESSID. The transceiver receiving the response can thus see the quality of the signal emitted by the access point. This quality depends on the distance between the transceiver and the access point and the properties of the transmission channel. When the transceiver is turned on, all the physical parameters are at their initial value and are only changed from the control station. These values are already mentioned in the technical description section of the transceiver. The preamble and the subject of the system according to the present invention use the frame of the standard used. However, it is conceivable to use only one modulator (DBPSK) to save time in processing the processor.

  Layered architecture: The architecture adopted by the system according to the present invention is the infrastructure mode, where the access point 19 is located at the workstation. The uplink and the downlink use the same frequency. Physical layer: The physical layer used depends on the standard used (DSSS for 802.11g and OFDM for 802.11a for example). The frame is shaped by the entity 106 and respects: • the bleaching of the frame, • the spread of the spectrum, the addition of the item, • the addition of the preamble • the addition of the CRC.

  Entity 106 calculates the signal-to-noise ratio (Eb / N) of the received signals and compares it with the (Eb / N) threshold of the modulation used. In the case where the result of the report is less than the threshold value, control 107 of the entity 107 to change the modulation used, this is called the dynamic variation of flow. For example, you can switch from DBPSK modulation for 1Mbps, to DQPKS for 2Mpbs, or QAM and CCK and Barker modulations to 54Mpbs with OFDM. The entities and their functions remain unchanged.

  The choice of channel and standard is made by the entity 106 by programming element 109. The control of the transmission power is always done by the entity 106 by programming the element 114. The MAC layer: Listening to the Carrier (CCA for 802.11, by

  example) is done by the entity 106 using the presence of the signal at the output of the entity 109, which also allows it to calculate the ratio (Eb / N) for the calculations of the bit error rate and of 1 EVM, two essential criteria for defining the loss of information when receiving frames.

  The purpose of element 106 is to encode the digitized data using data compression and CRC, since it also manages the inter-frame spacing mechanism (SIFS, DIFS, PIFS) which are respectively of the order of magnitude. (10ps, 50ps, 30ps).

  Our system will be able to adapt to other standards such as wimax because it already uses modulations, OFDM among others quoted by the norm 802.16 and the use of access modes such as OFDM or L '. OFDMA is however conceivable.

  Energy management: The system according to the present invention uses batteries or accumulators as a source of energy. To save this energy, a bistable magnetic switch can manage the transceiver power supply. In the case where the transceiver works with batteries, a repackaging of the system is necessary.

  In the case where the transceiver operates with accumulators, an induction charging can be performed. Two other possibilities are also envisaged: feeding by an electromagnetic wave which will be picked up by a passive circuit located inside the tranceiver, the energy supply by the energy recovered on the body of the subject (thermo life). In any case, we use the principle of standby, the transmission can be pulped so that the transceiver does not consume a significant amount of energy at all times. We will also use energy-saving components, which will also facilitate the integration of the transceiver.

  The invention is described in the foregoing by way of example. It is understood that one skilled in the art is able to realize different variants of the invention without departing from the scope of the patent.

Claims (5)

  An integrated system for the collection and electrical stimulation of cellular electrophysiological activities of deep organic structures and / or surfaces, comprising means for acquiring an electrical signal of cellular origin, characterized in that it further comprises means for transmitting data to a data storage and analysis system, by developing an improved telemetry using WLAN and HiperLAN systems, and including real-time data analysis means thanks to a software couple to the recording system, a suitable electrical signal being returned address; the latter is also transmitted by the same wireless link and allows direct action on the structure being explored or monitored.   2. Use of the integrated system according to claim 1 for the acquisition of biological signals such as EEG (ElectroEncephaloGram).   3. Use of the integrated system according to claim 1 for the acquisition of biological signals such as EMG (ElectroMyoGramme).   4. Use of the integrated system according to claim 1 for the acquisition of biological signals such as ECG (ElectroCardioGramme).   5. Use of the integrated system according to claim 1 for acquiring biological signals such as the arterial pressure sensor. 30