fig1 illustrates a brain analysis system 100 having an advantageous modular brain analysis sensor 400 applied to a forehead tissue site in communications with a physiological monitor 101 for measuring and generating simultaneous electroencephalogram ( eeg ) and left and right forehead regional oximetry ( ro2 ) parameter values and waveforms . the modular brain analysis sensor 400 can be advantageously assembled and placed within a limited - area forehead site . also , the ro2 components 600 and eeg component 500 can be advantageously purchased , stocked and used separately and individually , saving hospital and medical care center costs over other , more specialized brain analysis sensors not having separately useable regional oximetry and eeg sensor functions . the same cost savings is realized by modular designs for any and all types of physiological monitoring sensors . as shown in fig1 , the brain analysis sensor 400 has an eeg sensor ( fig4 - 5 ) that co - mounts dual regional oximetry ( ro2 ) sensors . each of these sensor functions are in communications with a physiological monitor 101 having a main display 120 and a ( removable ) handheld monitor 130 having a handheld display 132 . the main display 120 provides eeg waveforms and parameter values 122 in addition to forehead left 124 and forehead right 125 regional oximeter waveforms and parameters . the handheld display 132 provides a 3 - d man graphic displaying green , yellow and red organ symbols ( brain , lung and kidneys ) corresponding to eeg and / or ro2 parameter values . similar displays can be provided for other physiological parameters as well . also shown in fig1 , a modular brain analysis sensor 400 advantageously has dual ro2 sensors 600 that overlap right - and left - side portions of a specially - configured and marked ( ro2 - configured ) eeg sensor 500 so as to compactly fit these modular sensors 500 , 600 within a limited - space forehead site , as described in detail with respect to fig2 - 4 , below . an ro2 - configured eeg sensor 500 is described in detail with respect to fig5 a - e , below . an regional oximetry sensor 600 is described in detail with respect to fig6 a - e , below . further shown in fig1 , in an eeg screen portion 122 , the physiological monitor 101 display 120 shows 4 simultaneous eeg channels along with a patient state index ( psi ) readout versus time so as to enable continuous assessment of both sides of the brain , such as for improved anesthetic management . in addition , forehead left 124 and forehead right 125 regional oximetry waveforms and readouts enable monitoring of brain tissue oxygen saturation and detect regional hypoxemia . fig2 - 3 illustrate , respectively , a regional oximetry ( ro2 ) sensor and cable assembly and an eeg sensor and cable assembly . as shown in fig2 , the regional oximetry ( ro2 ) cable assembly 200 interconnects dual ro2 sensors 600 to a physiological monitor 101 ( fig1 ). the ro2 cable assembly has dual sensor connectors at a sensor end , a monitor connector ( moc9 ) at a monitor end and a ro2 pod mounted between and in communications with the sensor connectors and the monitor connector . also shown in fig2 , the ro2 pod has regional oximetry analog and digital boards . the analog board communicates with one or more of the regional oximetry sensors 600 . the digital board enables the pod to perform the sensor communications and signal processing functions of a conventional patient monitor . this allows pod - derived regional oximetry parameters to be displayed on a variety of monitors ranging from simple display devices to complex multiple parameter patient monitoring systems . as shown in fig3 , the eeg cable assembly 300 interconnects an eeg sensor 500 to a physiological monitor 101 ( fig1 ). the eeg cable assembly 300 has an eeg connector at a sensor end , a monitor connector ( moc9 ) at a monitor end and a eeg pod mounted between and in communications with the sensor connectors and the monitor connector . fig4 a - b illustrate a modular brain analysis sensor 400 having advantageous keyed mounting zones 501 ( shaded ) for precise , overlaid placement of dual ro2 sensors on an eeg sensor . in particular , the eeg sensor 500 has two mounting zones 501 , one on either side of the interconnected between the eeg electrodes and the eeg sensor connector . each mounting zone accommodates one of two ro2 sensors ( see fig1 and fig4 a ). further , each mounting zone 501 ( fig4 b ) is shaped and printed to conform to a top and side portion of an ro2 sensor head 610 ( fig6 a - d ). further , each mounting zone has printed notches 502 , 504 corresponding to actual notches in the ro2 sensor heads 610 ( fig6 a ) that accommodate curved tissue site surfaces . these printed notches 502 , 504 further aid in the alignment of ro2 sensors to the mounting zones 501 . fig5 a - e further illustrate an ro2 configured eeg sensor 500 having a generally “ t ” shape with six electrodes including two right electrodes r 1 , r 2 ; two left electrodes l 1 , l 2 ; a ground electrode cb and a reference electrode ct . as shown in fig5 a , the r 1 , r 2 , l 1 , l 2 and cb electrodes are disposed across the horizontal top of the “ t .” the reference electrode ct is disposed on the vertical middle of the “ t .” the advantageous mounting zone 501 ( fig4 b ) is disposed on either side of the vertical middle of the “ t ” proximate the horizontal top of the “ t .” as shown in fig5 e , the eeg sensor 500 has multiple layers including a release liner 510 that allows an attached ro2 sensor 600 ( fig1 ) to be removed and repositioned ; artwork 520 including ro2 sensor positioning lines 502 ( fig4 b ); a polyester substrate 530 ; silver pads 540 ( electrodes ); silver ink traces 550 ; a dielectric layer 560 that isolates and protects the traces 550 and a foam pad 570 that contacts a user &# 39 ; s skin . the eeg sensor connector includes a top shell 582 and a bottom shell 584 . an information element 585 mechanically and electrically connects to the trace layer 550 . fig6 a - e further illustrate a ro2 sensor and its optical elements having a sensor head 610 , a stem 620 and a connector 630 . the sensor head 610 houses an emitter 682 , a near - field detector 684 and a far - field detector 688 within a layered tape having a top side ( fig6 a ) and an adhesive bottom side ( fig6 c ) disposed on a release liner . the release liner is removed so as to adhere the bottom side to a skin surface . the emitter 682 and detectors 684 , 688 have lens that protrude from the bottom side ( fig6 e ) advantageously providing a robust optics - skin interface . the top side has printed emitter / detector indicators so as to aid precise sensor placement on a patient site . a connector 630 terminates the interconnect 620 at the connector contacts 632 . also shown in fig6 d , a sensor head assembly 610 has a face tape 612 , a flex circuit 622 , a stem tape 620 , a base tape 624 , a connector top 634 and a connector base 636 . the face tape 612 and base tape 622 encase the flex circuit 622 and corresponding emitter and detectors 682 - 688 . a modular physiological sensor has been disclosed in detail in connection with various embodiments . these embodiments are disclosed by way of examples only and are not to limit the scope of this disclosure and the claims herein . one of ordinary skill in art will appreciate many variations and modifications . it should be understood specifically that the present mounting zones , tabs , relative shapes and modular configuration can be applied to other physiological sensors including , for example , ear , nose , hand , harm , and / or chest sensors or any other types of physiological sensors where the sensors are configured to jointly measure the same measurement site of a patient .
modular physiological sensors that are physically and / or electrically configured to share a measurement site for the comfort of the patient and / or to ensure proper operation of the sensors without interference from the other sensors . the modular aspect is realized by providing outer housing shapes that generally conform to other physiological sensors ; mounting areas for attachment of one sensor to another sensor ; providing release liners on the overlapping sensor attachment areas ; and / or providing notches , tabs or other mechanical features that provide for the proper placement and interaction of the sensors .