Abstract:
A sensor system is used for measuring, transmitting, processing and displaying a brain parameter. The sensor system has an implantable brain parameter sensor with a wireless transmission unit for measuring the brain parameter. A receiving unit with an antenna is in wireless signal connection with the latter. A data read module is in signal connection with the antenna and a data processing and display device is in turn in signal connection with the data read module. The sensor system also has a head cap or a head hood, on which the receiving unit is fixed to predetermine a relative position relative to the transmitting unit. A sensor system is the result, the use of which remains comfortable for the patient even over a relatively long measuring period. A method for transmission of measurement data measured with the brain parameter sensor to the external data read module is also provided.

Description:
FIELD 
       [0001]    The invention relates to a sensor system for measuring, transmitting, processing and displaying a brain parameter with at least one implantable brain parameter sensor with a wireless transmission unit for measuring the brain parameter, with at least one receiving unit with an antenna, which is in wireless signal connection with the transmission unit, with at least one data read module, which is in signal connection with the antenna by means of a signal connection, and with at least one data processing and display device, which is in signal connection with the data read module. A method for transmission of measurement data measured with the brain parameter sensor to the external data read module is also provided. 
         [0002]    The invention also relates to a head cap or a head hood, respectively, for a sensor system of this type. 
       BACKGROUND 
       [0003]    A sensor system of the type mentioned at the outset is known from WO2004/023993 A1. Further sensor systems are known from EP 1 312 302 A2, DE 696 34 810 T2, DE 197 05 474 A1, DE 696 34 689 T2, U.S. Pat. No. 4,519,401 A and US 2003/0023146 A1. 
         [0004]    An EEG cap with sensors is known from DE 102 15 115 A1, said sensors forming a sensor grid to form a measuring device in a mechanism for reactive automatic non-invasive controlled or regulated electromagnetic prevention of epileptic fits in vivo. 
         [0005]    Brain parameter measurements take place, in particular, with the goal of clarifying the necessity for later therapy measures. An application example of this is a long term measurement of intracranial pressure for clarifying the question of whether a hydrocephalus patient requires a shunt valve and how a valve of this type has to be designed with regard to its dimensioning. Data collection of the intracranial pressure course over a relatively long time period, for example overnight or over several days is necessary for this in order to be able to derive a diagnosis from the dynamics of the intracranial pressure (ICP). 
         [0006]    The use of the previously known sensor systems for processing questions of this type is very uncomfortable and cumbersome for the patient. 
       SUMMARY 
       [0007]    An object of the present invention is to develop a sensor system of the type mentioned at the outset in such a way that the use thereof remains comfortable for the patient even over a relatively long measuring period. 
         [0008]    This object is achieved according to the invention by a sensor system comprising a head cap or a head hood, on which the receiving unit is fixed to predetermine a relative positioning relative to the transmission unit. 
         [0009]    It was recognised according to the invention that the components which are necessary to receive the measurement data from the implanted brain parameter sensor can be designed to be so light and compact that they can easily be fastened to a head cap or a head hood. The head cap or the head hood protects the receiving unit. The patient can move substantially freely with the head cap or the head hood, in other words, does not have to be accommodated stationarily during the measuring period. The head cap or the head hood ensures an exact relative position of the receiving unit with respect to the transmission unit. 
         [0010]    An antenna being part of a printed circuit is particularly light and compact and therefore comfortable to wear. 
         [0011]    The receiving unit being fixed to the head cap or the head hood by a hook-and-loop connection allows a site-flexible relative positioning to adjust the receiving unit relative to the transmission unit. For this purpose, the receiving unit can be steplessly displaced relative to the head cap or the head hood until an intended desired signal strength is achieved in the transmission between the transmission unit and the receiving unit. It is possible, in particular, to make the axes of symmetry of the transmission unit and the receiving unit practically completely overlap one another, which ensures very good quality of the signal transmission. 
         [0012]    A grid network head cap or head hood has proven successful in use in conjunction with EEG (electroencephalography) systems. A corresponding grid network head cap or head hood may also be used, after equipping with a corresponding receiving unit, in the sensor system, in which the head cap or the head hood has a plurality of individual bands or individual tubes, which predetermine a grid network, wherein the receiving unit can be fixed on crossing points of the grid network. 
         [0013]    A housing ring by means of which the receiving unit can be placed on a patient&#39;s head ensures that the receiving unit rests securely on a patient&#39;s head. As the transmission unit is generally accommodated between the scalp and the cranium, the transmission unit is a clearly feelable elevation on the patient&#39;s head. The housing ring is preferably dimensioned such that it surrounds this elevation at least in portions and this improves the relative positioning of the transmission unit with respect to the receiving unit. 
         [0014]    Only some of the components forming the receiving unit can be accommodated in the housing or housing ring which can be placed on the patient&#39;s head. Preferably only the antenna of the receiving unit is accommodated in the housing or housing ring, whereas the other components of the receiving unit are connected to the antenna, for example, by means of a cable-bound or else a cable-less signal connection. The component which can be placed on the patient&#39;s head can then be configured in a light and compact manner. 
         [0015]    Configurations comprising a flexible membrane, by means of which the receiving unit can be placed on the patient&#39;s head, and wherein a layer of variable shape, in particular a gel layer, is arranged between the flexible membrane and the antenna improve the placing of the receiving unit on the transmission unit and therefore the relative positioning of these two units. 
         [0016]    An integration wherein the data read module and the receiving unit are configured as an integral modular unit and can be fixed to the head cap or the head hood avoids, in particular, the patient having to also carry additional components, for example, on the belt, in addition to the head cap or the head hood. 
         [0017]    The advantages of a head cap or a head hood with a receiving unit for use in a sensor system according to the invention correspond to those which were already stated above with reference to the sensor system according to the invention. 
         [0018]    An embodiment of the invention will be described in more detail below with the aid of the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  shows a sensor system for measuring, transmitting, processing and displaying a brain parameter; 
           [0020]      FIG. 2  schematically shows a section through a head cap or a head hood of the sensor system placed on a patient&#39;s head in the region of an antenna fixed to the head cap or the head hood; and 
           [0021]      FIG. 3  schematically shows an embodiment in which the head cap is configured as a network of a plurality of individual bands or individual tubes. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    A sensor system  1  shown as a whole in  FIG. 1  is used to measure, transmit, process and display a brain parameter, in particular an intracranial pressure. 
         [0023]    The sensor system  1  includes a brain parameter sensor  24 , and can be implanted in a patient&#39;s head. The cutout-wise cross section of  FIG. 2  shows components of the implanted brain parameter sensor  24 , which are arranged between a cranium  2  indicated by a dashed lines in  FIG. 2  and the scalp  3  of a patient. A wireless sensor transponder  4  with an antenna coil is part of the brain parameter sensor  24 . The sensor transponder  4  is also designated a transmission unit below. The transmission unit  4  is in electrical contact by means of a line  5  and a rectifier  28 , with a capacitor  6 . The view according to  FIG. 2  is extremely schematic and not true to scale. 
         [0024]    The sensor transponder  4  does not have its own energy source. The sensor transponder  4  additionally has an analogue to digital converter  29 . This is used to digitise the sensor measurement data to be passed on from the sensor transponder  4 . 
         [0025]    An axis  7  of rotational symmetry of the antenna coil of the transmission unit  4  is shown by dashed lines in  FIG. 2 . The axis  7 , due to the arrangement of the transmission unit  4 , runs substantially normal to the outer wall of the cranium  2  in the region where the antenna coil of the transmission unit  4  rests thereon. 
         [0026]    The transmission unit  4  is connected to sensor element of the brain parameter sensor, by means of a signal connection, not shown. The sensor element is, for example, configured as a catheter guided through the cranium  2  with a pressure measurement head. 
         [0027]    Associated with the transmission unit  4  is an outer transceiver unit  8  of the sensor system  1 , which will also only be called a receiving unit or a reader below. The receiving unit  8  is arranged outside the patient&#39;s head. The receiving unit  8  has an antenna  9 , which is wirelessly in signal connection with the transmission unit  4  for the supply of energy and for data transmission. The antenna  9  is printed as part of a printed circuit (PCB, printed circuit board) on a thin board  10  with a thickness of between 0.8 mm and 1.5 mm. An even thinner board is also possible. To improve the adaptability of the receiving unit  8 , the board  10  may be configured as flexible, in other words a bendable board. The antenna  9  also has the shape of a coil, the axis of rotational symmetry coinciding with the axis  7 . The coil windings of the units  4 ,  8  may, in particular, be arranged helically. 
         [0028]    The board  10  is fastened to an annular housing  11  with a diameter of a few cm. The axis of rotational symmetry of the housing  11  also coincides with the axis  7 . The site of fastening of the board  10  is on a side of the housing  11  remote from the scalp  3 . 
         [0029]    A flexible membrane  12  is also fixed to the housing  11  on the side facing the scalp  3 . The membrane  12  thus lies between the antenna  9  and the scalp  3 . 
         [0030]    Arranged between the antenna  9  and the membrane  12  is a layer  13  of a resilient material of variable shape, in particular made of a flowable and highly viscous material, in particular made of a gel. 
         [0031]    When placing the receiving unit  8  via the housing  11  on the scalp  3  in the region of the transmission unit  4 , the membrane  12 , because of a targeted displacement of the layer  13 , adapts to the shape of the patient&#39;s head at this point, so a correct seat of the receiving unit  8  relative to the transmission unit  4  is ensured. 
         [0032]    The receiving unit  8  is fixed on the inside of a head cap or a head hood  14 , which is also part of the sensor system  1 . A hook-and-loop connection with a hook-and-loop band  15  which is stuck on the side facing the head cap or the head hood  14  on the housing  11  and the board  10  of the receiving unit  8 , is used to fasten the receiving unit  8  on the head cap or the head hood  14 . The receiving unit  8  can be applied at any point on the inside of the head cap or the head hood  14  by means of this hook-and-loop connection, so a desired relative positioning of the receiving unit  8  with respect to the transmission unit  4  is possible. The head cap or the head hood  14  is made of an expandable gauze or cotton material closely adjacent to the patient&#39;s head. The head cap or the head hood  14  is adapted in section to the shape of the patient&#39;s head. The head cap or the head hood  14 , for fixing to the patient&#39;s head, may have a chin band, not shown in the drawing. In addition to the head cap or the head hood  14 , an outer overcap or overhood  16  indicated by dashed lines in  FIG. 2  may also be provided, which absorbs forces from the outside and therefore secures the then inner head cap or head hood  14  against undesired slipping relative to the cranium  2 . 
         [0033]    The antenna  9  of the receiving unit  8  is in signal connection with a data read module  18  by means of a signal cable  17 , which extends in portions between the scalp  4  and the head cap or the head hood  14 . The data read module  18  comprises a control unit for controlling the implanted brain parameter sensor by means of the receiving unit  8 , by means of which a bidirectional data transmission is possible. Furthermore, the data read module  18  has a high frequency source for generating a carrier frequency of 13.56 MHz. The data read module  18  additionally has a signal memory. The data read module  18  approximately has the size of a cigarette packet and can be carried by the patient on the belt. 
         [0034]    The data read module  18  is in signal connection by means of a further signal cable  19  with a data processing and display device  20 . The latter has a display  21  and a plurality of operating buttons  22  and connection ports  23 , in particular at least one USB interface. The data processing and display device  20  can be connected to an external voltage source. As an alternative or in addition, the data processing and display device  20  may have an internal energy source, for example in the form of battery or a chargeable accumulator. The data read module  18 , the receiving unit  8  and, wirelessly during a measurement process, also the transmission unit  4  are supplied by means of this energy source. 
         [0035]    The signal connection between the antenna  9  and the data read module  18 , on the one hand, and the data read module  18  and the data processing and display device  20 , on the other hand, may be a USB interface or else an RS232 interface, in other words, a digital interface. 
         [0036]    A brain parameter measuring process, which is regularly repeated over a relatively long time period, for example over the course of several days, proceeds as follows: 
         [0037]    The data read module  18  firstly sends by means of the receiving unit  8  an HF signal to the transmission unit  4 . The HF signal is rectified and charges the capacitor  6  for the temporary energy supply of the transmission unit  4 . After this charging process, the HF signal is deactivated. 
         [0038]    The brain parameter sensor, supplied by means of the capacitor  6 , then records the brain parameter measurement signal, for example, an intracranial pressure value. The HF signal is then activated again and the transmission unit  4 , with the HF signal as the carrier frequency, sends the measurement value digitised by means of the analogue to digital converter  29  as a digitally modulated signal to the receiving unit  8 . A conversion or decoding of the modulated HF signal into a digital PC-compatible signal takes place in the receiving unit  8 . Depending on the interface standard used in the sensor system  1 , this may, for example, be a USB or an RS232 signal. This converted measurement signal is transmitted to the data read module  18  by means of the signal cable  17 . The transmitted signal is then transmitted by the signal cable  19  to the data processing and display device  20  for further processing and display. 
         [0039]    Instead of a gauze or cotton configuration of the head cap or the head hood  14  and optionally the overcap or overhood  16 , the head cap or the head hood  14  may also be configured as a network of a plurality of individual bands or individual tubes. A grid network is then predetermined by these individual bands or individual tubes. The receiving unit  8  may then have fastening means  25  on the individual bands or individual tubes  26  which, in particular, allow the receiving unit  8  to be fastened to crossing points  27  of this grid network. Corresponding embodiments of head caps or head hoods of individual bands or individual tubes are known in conjunction with EEG head caps or head hoods. 
         [0040]    In a further variant of the sensor system  1 , the receiving unit  8  and the data read module  18  are configured as an integrated modular unit and fastened to the head cap or the head hood  14 . For the weight distribution of this integrated modular unit, the data read module can also be fastened separately from the receiving unit  8  on the inside of the head cap or the head hood  14 , for example at a position opposing the receiving unit  8 . The receiving unit  8  and the date read module  18  may then be connected to one another by means of a short signal cable. 
         [0041]    A corresponding integration of the receiving unit  8  is also possible with individual components of the data read module  18 , for example with the HF source or with the control unit of the data read module  18 . The remaining components are then in turn connected by means of a signal connection to an external module, in other words a module provided outside the head cap or the head hood  14 . 
         [0042]    In these integrated variants, in which the receiving unit  8  also has additional components of the data read module  18 , it is also possible for the receiving unit  8  to have its own energy supply, for example in the form of a button cell. In this case, a cable-bound signal connection may also be dispensed with and, instead of the signal cable  17 , a wireless signal connection, for example a Bluetooth signal connection, may be used. 
         [0043]    In a further variant of the sensor system  1 , the data read module  18  has its own energy supply and, instead of a cable-bound signal connection to the data processing and display device  20  (signal cable  19 ), a wireless signal connection is present, which can also be implemented, for example, by means of a Bluetooth connection. 
         [0044]    The data processing and display device  20  does not have to be constantly in signal connection with the data read module  18 . It is sufficient if the data processing and display device  20  reads the recorded measurement data from the data read module  18  on completion of the measuring time, for example lasting several days. A corresponding data connection is necessary only then, so the patient only has to wear the head cap or the head hood  14  with the receiving unit  8  and the data read module  18  during the measuring time. 
         [0045]    The site-flexible positioning of the receiving unit  8  by means of the hook-and-loop connection with the hook-and-loop band  15  allows an exact orientation of the receiving unit  8  with respect to the transmission unit  4 , so the coil axes of these two units  4 ,  8  coincide. This ensures an optimal signal transmission between the units  4  and  8 . 
         [0046]    In an embodiment, not shown in more detail, the receiving unit  8  is configured with an annular housing  11 , in which an also annular antenna  9  is incorporated. This ring antenna in this embodiment is placed on the head of the patient. The remaining receiving unit, in other words the further components, which in the embodiment according to  FIGS. 1 and 2  are configured, in particular, on the printed circuit on the board  10 , are connected to the ring antenna by means of a data cable. This remaining receiving unit may be carried, for example on the belt or placed on a laboratory table. This separation of the ring antenna from the other receiving unit reduces the overall size and the weight of the component to be placed on the head of the patient. 
         [0047]    The housing of the ring antenna of this embodiment, not shown further, may have characteristic bulges and/or troughs and/or other indentations, which are used, when manually placing the ring antenna, to facilitate the positioning thereof. For example, three bulges and/or troughs and/or indentations may be present, which are arranged approximately equally distributed on the outer periphery of the ring antenna. 
         [0048]    The housing of the ring antenna may have radially extending indentations on the upper side of the ring antenna remote from the patient&#39;s head in the placed-on position. These radially extending indentations may be used as fastening aids for a hook-and-loop band for fixing the ring antenna to the head cap or the head hood  14 .