WO2007071844A1

WO2007071844A1 - Device for transmitting physiological signals of a wearer

Info

Publication number: WO2007071844A1
Application number: PCT/FR2006/002800
Authority: WO
Inventors: Joel Paquereau; Stéphane BESNARD; Jérome BILLOUE; Malika Moulessehoul; Didier Magnon
Original assignee: Universite De Poitiers; Universite Francois Rabelais De Tours; Centre Hospitalier Universitaire De Poitiers
Priority date: 2005-12-19
Filing date: 2006-12-19
Publication date: 2007-06-28
Also published as: EP1962678A1; FR2894805A1

Abstract

The invention relates to a device for transmitting physiological signals of a wearer comprising: a sensor capable of being positioned on the wearer so as to pick up physiological signals; wireless transmission means designed to transmit physiological data representative of the physiological signals through a wireless channel, characterized in that the sensor is identified by a unique identifier, and the transmission means comprise formatting means designed to format said physiological signals in a data format defined by frames having a payload, the formatting means moreover being designed to insert said unique identifier into said payload so as to form said physiological data.

Description

DEVICE FOR THE TRANSMISSION OF PHYSIOLOGICAL SIGNALS OF A BEARER

The invention relates to a device for the transmission of physiological signals of a carrier.

After acquisition by physiological signal sensors on a patient, these physiological signals can be transmitted to an analysis device either by a wireless path or by a wired path.

When many sensors are positioned on a patient, or where physiological signals are to be collected from multiple patients in a small space, it is advantageous that these signals be transmitted over a wireless path. In this way, son do not interfere with the patient or patients in their movements or movements.

Application US 2004/0015058 discloses a device for transmitting physiological signals of a carrier comprising:

a sensor that can be positioned on the wearer so as to capture physiological signals;

wireless transmission means arranged to transmit physiological data representative of the physiological signals by a wireless channel.

The wearer can be an animal or a human.

In the system described in the aforementioned application, when the carrier carries several sensors, it is not possible to determine from which sensor a signal has been transmitted. Moreover, if several such systems were positioned at the level of several patients, it would not be possible to determine which patient corresponds to the data received. Thus, a simultaneous transmission of several signals from the sensors is impossible if we want to obtain usable data.

The invention aims to overcome this drawback.

The problem solved by the invention is therefore to be able to perform simultaneous measurements of several physiological signals.

This problem is solved according to the invention by the fact that the sensor is identified by a unique identifier, and by the fact that the transmission means comprise formatting means arranged to format said physiological signals in a data format defined by frames. having a payload, the formatting means being further arranged to insert said unique identifier in said payload so as to form said physiological data.

In this way, the physiological data transmitted comprise, within the frame, an identifier of a sensor that has generated the physiological signal. In the case of simultaneous transmission of several physiological data wirelessly, it is therefore possible to determine with certainty which acquisition means have transmitted the physiological data.

According to one embodiment, the device may comprise a plurality of sensors, each of the sensors of the plurality of sensors being identified by a unique identifier. The identifier of each sensor is then advantageous in this case even in the context of the use of a single device according to the invention.

In the aforementioned device, the sensor is associated with a sampling frequency according to the unique identifier of the sensor and the formatting means are arranged to insert the sampling frequency into the payload. this allows to acquire in parallel signals with different frequency contents and different natures.

In the aforementioned device, the sensor may comprise an amplifier having a gain depending on the unique identifier of the sensor and the formatting means may be arranged to insert the gain in the payload. This makes it possible to acquire signals of different types requiring different gains.

The above-mentioned device may also comprise a clock associated with the formatting means, the formatting means being arranged to insert into the payload the start time and the end time of capture by the sensor. This makes it possible to resynchronize the physiological data in case of loss of certain data.

The invention also relates to a system comprising:

a device as previously described,

- a checkpoint the device being able to transmit the physiological data to the control station.

In the aforementioned system, the control station can be arranged to transmit control data to the device.

The control data may include the sampling frequency and / or the gain. This allows in particular to set the data of the frame that will be transmitted by the device.

In the aforementioned system, the device may also be arranged to apply a stimulation signal in response to the control data. This makes it possible to use the device according to the invention both in detection and in stimulation. The invention also relates to a method for transmitting physiological signals of a carrier comprising steps in which: a sensor captures physiological signals; physiological data representative of the physiological signals are transmitted by a wireless channel; characterized in that the sensor is identified by a unique identifier and wherein the method comprises steps wherein: - said physiological signals are formatted in a data format defined by frames having a payload; said unique identifier is inserted into said payload so as to form said physiological data.

The measuring instrument:

The first aspect of the present invention is to provide a medical measuring instrument for the collection and electrical stimulation of cellular electrophysiological activity of deep organic structures. It can also achieve the acquisition of biological signals such as EEG (ElectroEncephaloGramme), EMG (ElectroMyoGramme), ECG (ElectroCardioGramme), arterial pressure reading, ...

This instrument with implantable and / or surface sensors, can be used for any physiological analysis such as:

*> the survey of the cellular potentials more or less deep, <* the sleep,

*> the heart rate,

*> the blood pressure,

<* epilepsy, *> 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 a therapeutic purpose 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, etc. applications.

The principle of the present invention uses the basics of communication protocols of wireless networks dedicated to few immobile devices that require high bandwidth. In contrast, we use our network with many devices that can be slightly mobile but need a very low bandwidth (from 500Hz to 1kHz). 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 on 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 biological signals). The whole formed by the system and the telemetry system does not require additional devices to communicate with the remote control station. Only software is needed on the latter for visualization and control of signal measurement parameters. The control station has a wireless connection through an access point.

The transceiver is easily concealed as it benefits from the latest advances in microelectronics integration.

Platform of the invention

The present patent application covers virtually all 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 achieve the acquisition of biological signals such as EEG (ElectroEncephaloGramme), EMG (ElectroMyoGramme), ECG (ElectroCardioGramme), arterial pressure reading, ...

The physiological signals as they present themselves can not be directly exploited, given their small amplitude which varies from the microvolt to ten millivolts. Therefore an acquisition / amplification system 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),

*> filtered low and high frequency spurious signals (high-pass and low-pass filters with variable cutoff frequency), *> digitized (the number of bits is ≥ 4 with no actual upper limit),

*> encoded (any baseband encoding may be used), *> compressed (all coding techniques may be implemented, including co-coding),

^» > Formatted (constitution of a frame of our own),

modulated (the modulations used are those defined in the software layers of wireless networks),

* transmitted over the air (in accordance with the standards in force, 802.1 1, 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 nature or not, but it can also have only one sensor. Whatever the number, a sensor is either surface or depth, that is to say within physiological structures. A transceiver may have sensors both surface and / or depth.

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

We use the communication protocols of wireless networks, governed by the standards in force 8021.1 1, 802.16, ..., to transmit signals with a very small spectral space.

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

The access mode adapted 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 reservation of the medium (RTS \ CTS, for example) and mechanisms of acknowledgments, each transceiver can transmit data by calculating a random delay (algorithm used in Ethernet frames). When collisions are not avoided (loss of information), the physical layer uses the FEC mechanism (Forward Error Correction) 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, following a theoretical study relating the different transmission standards and their feasibility to transmit biological data. It has been validated on a real transmission 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 known and future digital modulations for RF transmission can be used (examples: DBPSK, DQPSK, QAM). Thus the bit rate can vary according to the modulation to adapt to the environment. It is also possible to remedy the channel fading problem by using techniques such as spectrum spreading (barker code and CCK) or OFDM found in the CDMA access mode (which uses the same principle that barker and CCK codes) 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 provides an error control mechanism (CRC) for verifying the integrity of the frames. The access point: *> acts as the server, *> manages access to the medium,

*> controls the transmit power of the transceiver, *> sends control bursts to each connected transceiver to prevent 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 by means of the description, given below purely for explanatory purposes, of one embodiment of the invention, with reference to the appended figures: FIG. 1 is a diagram of the transmitter - receiver (transceiver) and access point; FIG. 2 represents an exemplary frame transmitted from the transceiver according to one embodiment of the invention;

FIGS. 3A to 3C show examples of frames transmitted from a control station to the transceiver according to one embodiment of the invention; Figure 4 shows the frame used in detail; Figure 5 illustrates the frame in the animal; and - Figure 6 illustrates the frame in humans.

The transceiver is composed of the different parts shown in Figure 1.

Signals pass from the transceiver to the access point

100: It is the sensor that converts our physical quantity into an electrical signal that can be processed by the transmitter. It is either placed on the surface of the body or introduced deep into the cell 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 surface, impedance, stainless. The impedance of the sensors used in the system according to the present invention varies from a few kΩ to several MΩ depending on their type.

101: The sensor 100 is directly connected to one of the differential inputs which is a very low noise preamplifier. 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 one tenth of the lowest 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 between the differential mode gain and 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 broken down 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 of course eliminates all the BF therefore the offset voltage from the preamplifier. 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 cutoff frequencies are programmable, it is preferable to set for the main application according to the invention a bandwidth of 3 Hz to 1 OkHz. 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 pulsed.

It incorporates a rewritable program memory, even in "run" mode, a data memory as well as an analog / digital converter. The sampler is integrated or not into the processor. It can work at a frequency ≥ 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 coded identifier 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. In the end, the processor provides the frame containing the data that must 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 in order to synchronize the two processors. 107 adds to this frame the preamble and the header used in the standard. The complete pattern thus formed is "bleached", using a pseudo random sequence, and then "mapped" by modulation for the header (DBPSK for example) and the preamble is coded (barker for example) to achieve the highest possible rate. The data is mapped according to the desired dynamic flow rate, which depends on the environment, then they are coded (barker or CCK for example). Then, a digital / analog converter, integrated or not integrated in the 107, makes the analog output signal. An electronic switch (switch) allows the choice of a standard (802.1 1g, 802.1 1a, for example).

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

109: It is a modulator which 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 becomes asymmetrical thanks to the balun 1 10.

1 1 1: it is a filter which respects the Nyquist condition, and which limits the signal spectrum at the output of 110 to avoid inter-symbol interference.

112: The signal thus filtered by 1 1 1 is then amplified 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 1 14. This element deserves special attention because it contributes greatly to the level of reception and / or emission of the signal, which is essential to remedy the fading problem (Fading). 1 14: The access point receives and transmits 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.

1 15: An interface allows from the control station 1 15 to view and analyze the signals received from each transceiver. Software dedicated to medical applications can be used.

Signals pass from the access point to the transceiver

1 15: A man / machine interface gives the possibility to send commands from the access point to all tranceiver, examples: • the change of gain,

• change of sampling frequency,

• 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 the 1 14 which converts it into a frame respecting the mandatory parts that the chosen standard imposes. The process for bringing the signal to the antenna of the access point is identical to that described above.

1 16: After reception by the antenna 1 13, if the message is intended for this transceiver, the RF signal passes through a low noise amplifier 1 16. It then takes the opposite path to that described above, ie:

• the bandpass filter 1 1 1 eliminates the BF and the HF at the output of the 116,

The balum 1 10 transmits a symmetrical signal at 109, The RF signal is rid of its carrier in 108,

• it is demodulated and decoded in 107,

• a serial or parallel synchronization link between 107 and 1 16 makes possible the extraction of the 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 change in bandwidth, o a launch of data acquisition, o a stimulation of a biological zone via a sensor, ...

Once the action (s) has been completed, the transceiver is ready to transmit or receive information again.

Other circuits

1 17: A guard circuit connects the transceiver to the sensor shield to counteract the common mode voltage of 100 which alters the received signal.

1 18: Equipotentiality or reference of the subject with respect to the mass of the system can be ensured in various ways:

• by a traditional DRL circuit,

• by sensors connected to the mass on each transceiver,

By a synthetic 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 achieve a neutral point with respect to the measurement in progress. The transmission frames according to the invention are now described.

The transmission protocol used in the present invention complies with the standards in force but changes certain parameters concerning in particular the data frame. In authorized locations, additional information is passed over biological data.

FIG. 2 illustrates an exemplary frame according to one embodiment of the invention. The data shown in FIG. 2 are for example inserted into the payload of a frame in the format corresponding to the transmission protocol used. Formatting is done by the processor at runtime.

As described above, each transmission module according to the invention comprises a radio frequency chip. In a manner known per se, this radiofrequency chip is identified by a MAC address. The transceiver module of the invention is therefore identified by this MAC address. The MAC address is inserted into the frame transmitted to the control station 1 15. When the transceiver module comprises only one sensor, this MAC address is a unique identifier of the sensor.

Within each transceiver module, different sensors 100 can acquire data. The variable ENSENS includes the list of sensors 100 activated within the transceiver module.

The variable Gi corresponds to the gain of the sensor i. The data Gi may vary depending on the number of selected sensors. The variable Gi is programmable when sending a command frame as will be described in more detail below. The index i of the sensor is a unique identifier of the sensor which can be stored in a memory of the transceiver module. The values Fj indicate the acquisition frequency of the signal collected on the sensor i. It is therefore possible to acquire, in parallel, signals with different frequency contents, therefore of different natures.

The values to, ti enable synchronization, at the control station 1 15, of the data acquired on each sensor i for successive data frames. This technique allows the receiver to readjust the signal in case of data loss during the transmission of a frame.

The fields data i contain the data collected from the sensor i between the time to and ti at the frequency Fi.

Such a frame is thus formatted at the processor 106 of the transceiver module.

At the level of the control station 1 15, the format of the frame thus transmitted is recognized so as to reconstruct the different physiological signals sensed by each of the sensors.

At the beginning of a measurement campaign the control station 1 15 sends a control frame to the transceiver module to apply the parameters, IDGR, ENSENS, Gi and Fj. It is also possible to activate or pause a transceiver module and send pacing signals.

The activation of a transceiver module is performed by sending a data frame from the control station 115 to the transceiver module. Such an activation frame is illustrated in FIG. 3A. It includes the IDGR ID of the transceiver module group to activate, a command code, and an ON / OFF activation or deactivation command. The order code includes for example the stimulation frame code, the type of stimulation, in particular current or voltage, and the shape of the stimulation.

The parameters of the sensors 100 of a transceiver module according to the invention can be determined by a parameter control control frame as shown in FIG. 3B. Such a frame comprises the IDGR ID of the transceiver module group to be set, a control code, an ENSENS variable comprising the list of sensors 100 activated within the transceiver module. It also includes data G ₀ , Gi, Gn, and F ₀ , Fi, Fn respectively corresponding to the gains and sampling frequencies of the sensors to be adjusted.

The stimulation is then performed by the transmission of a stimulation frame for example as illustrated in FIG. 3C. This frame comprises in particular variables Ai corresponding to the stimulation amplitude of the sensor i, and rcy, corresponding to the duty cycle of the signal on the sensor i. A rcyi value of 0 coding for the emission of a pulse.

Other examples of transmitted frames according to the invention will now be described.

An example is first described for detection in animals.

The system according to the present invention makes it possible to study several groups (IDGR) of several animals (IDAN), each animal having several sensors (CAPj). We will have at least the information shown in Figure 5. With:

• Gi the gain of the sensor i,

• f ₀ , the sampling frequency,

• to, the time of the beginning of acquisition, • ti, the end of acquisition time,

• Nbrcap, the number of activated sensors,

• Scapi, the data collected on the sensor i to to, to + (1 / fo), ... until t-i.

To this must be added the identification bursts of each sensor, plus the 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 transceiver, we can 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 (CAPj). We will have at least the information shown in Figure 6.

With:

• Gi the gain of the sensor i,

• fo, the sampling frequency, • t ₀ , the time of the beginning of acquisition,

• ti, the end of acquisition time,

• Nbrcap, the number of activated sensors,

• Scapi, the data collected on the sensor i to to, t _o + (1 / fo), ... up to ti.

To this must be added the identification bursts of each sensor, plus the 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, or at least 12 transceiver in the case of an EEG for example. Here, it is therefore the IDPA parameter that will have to be important if one wishes to make measurements on several patients simultaneously.

Whether in humans or animals, parameter frames are sent by the access point to each transceiver to initialize 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 shift 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. Knowing that the size of the frame is between 6 and 2312 bytes.

Access mode:

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

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 a rate of about every 0, 1 seconds) a beacon frame (named beacon) giving:

^• information on the BSSI D, ^• its characteristics

^• possibly his ESSI D.

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 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 header 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.

The layered architecture:

The architecture adopted by the system according to the present invention is the infrastructure mode, where the access point 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 802.1 1g and OFDM for 802.1 1a for example). The frame is formatted by the entity 106 and respects: • the whitening of the frame, spread spectrum, adding the header,

• adding the preamble

• the addition of the CRC).

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

The choice of the channel and the standard is made by the entity 106 by programming the element 109. The control of the transmission power is always done by the entity 106 by programming the element 1 14.

The MAC layer:

The carrier listening (CCA for the 802.1 1 standard, for 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 calculations of the bit error rate and the EVM, two essential criteria for defining the loss of information upon reception of the frames.

The purpose of the element 106 is to encode the digitized data using data compression and the CRC, since it also manages the interframe spacing mechanism (SIFS, DIFS, PIFS) which are respectively of the order of (10μs, 50μs, 30μs). Our system will be able to adapt to other standards such as wimax because it already uses modulations, OFDM among others cited by the 802.16 standard and the use of access modes such as OFDM where 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 case 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 that will be picked up by a passive circuit located inside the tranceiver, • feeding by the energy recovered on the body of the subject (thermo life).

Be that as it may, we use the principle of standby, the transmission can be pulsed so that the transceiver does not consume a significant amount of energy permanently. We will also use low-power components, which will further facilitate transceiver integration.

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

Claims

1. Device for the transmission of physiological signals of a carrier comprising:

wireless transmission means arranged to transmit physiological data representative of the physiological signals by a wireless channel, characterized in that the sensor is identified by a unique identifier, and the transmission means comprise formatting means arranged to format said physiological signals in a data format defined by frames having a payload, the formatting means being further arranged to insert said unique identifier in said payload so as to form said physiological data.

2. Device according to claim 1 comprising a plurality of sensors, each of the sensors of the plurality of sensors being identified by a unique identifier.

3. Device according to claim 1 or 2 wherein the sensor is associated with a sampling frequency according to the unique identifier of the sensor (Fi) and wherein the formatting means are arranged to insert the sampling frequency in the payload.

4. Device according to one of claims 1 to 3 wherein the sensor comprises an amplifier having a gain function of the unique identifier of the sensor (Fj) and wherein the formatting means are arranged to insert the gain in the payload .

5. Device according to one of the preceding claims comprising a clock associated with the formatting means, and wherein the formatting means are arranged to insert into the payload the start time and the end time of capture by the sensor .

6. System comprising:

a device according to any one of claims 1 to 4;

- a checkpoint (1 15); the device being able to transmit the physiological data to the control station.

7. System according to claim 6 wherein the control station being arranged to transmit control data to the device.

The system of claim 7 wherein the control data comprises the sampling frequency.

The system of claim 8 wherein the control data comprises the gain.

10. System according to one of claims 6 to 9 wherein the device is arranged to apply a stimulation signal in response to the control data.

A method for transmitting physiological signals of a carrier comprising steps wherein:

a sensor captures physiological signals; physiological data representative of the physiological signals are transmitted by a wireless channel; characterized in that the sensor is identified by a unique identifier and wherein the method comprises steps in which: said physiological signals are formatted in a data format defined by frames having a payload;

said unique identifier is inserted into said payload so as to form said physiological data.

The method of claim 11 wherein a plurality of sensors capture physiological signals, each of the plurality of sensors being identified by a unique identifier.

13. Method according to one of claims 1 1 or 12 wherein the sensor is associated with a sampling frequency according to the unique identifier of the sensor (Fj) and wherein the method comprises a step in which:

- the sampling frequency is inserted in the payload.

14. Method according to one of claims 11 to 13 wherein the sensor comprises an amplifier having a gain function of the unique identifier of the sensor (Fj) and wherein the method comprises a step in which: - the gain is inserted into the payload.

15. Method according to one of claims 1 1 to 14 comprising a step in which:

- The start time and the capture end time by the sensor is inserted into the payload.