Patent Publication Number: US-2023147868-A1

Title: Face device for monitoring biomedical parameters of a user

Description:
This application is a § 371 National Stage Entry of International Patent Application No. PCT/IB2021/052612 filed Mar. 30, 2021 which claims priority of Patent Application No. EP 20166717.7 filed Mar. 30, 2020. The entire content of these applications is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to a face device that is able to monitor biomedical parameters of a user wearing the face device. 
     PRIOR ART 
     In many professions in a hostile environment, for example with a high chemical or biological risk, or in environments potentially lacking in oxygen, the operators need to protect their faces with personal protective equipment. For example, in the case of protective equipment for the respiratory tract, operators use masks with or without filters, half-masks or full face masks, aqualungs or respirators with external air supply, or in the case of protective equipment for the eyes, the operators use goggles, masks, visors and screens. In most of the aforesaid professions, it would be desirable to monitor heartbeat and oxygen saturation in the blood of the operator to ensure that environmental conditions have not compromised breathing capacity and thus the health of the operator or have not caused the operator to lose consciousness. 
     Many sporting activities, both those considered to be extreme such as for example scuba diving in apnoea or with aqualungs, or parachuting, paragliding, wingsuit flying, or mountaineering, free climbing, extreme downhill cycling, but also sporting activities that are considered to be non-extreme disciplines like cycling, skiing and snowboarding involve an intense psychomotor and breathing effort accompanied by a high level of adrenaline and also involve the hands being engaged by the activity. Also, in all these cases it is important, both during the training phase and during the sporting discipline proper, to be able to measure the biomedical parameters like heartbeat and oxygen saturation in the blood. 
     For example, in scuba diving in apnoea, during the apnoea phase, the level of oxygen in the blood decreases continuously and on the other hand the level of carbon dioxide increases, at a speed that depends on various factors such as for example the heartbeat frequency, the temperature of the water, muscular effort, psychophysical conditions, and other things. The human organism is not able to evaluate the quantity of oxygen in the blood, but manages to send some signals, such as for example contractions of the diaphragm, which are triggered exclusively by an increase in carbon dioxide. Nevertheless, these signals are not easily interpretable and also an expert freediver could be mistaken in evaluating the availability of oxygen during the immersion. 
     Should the level of oxygen fall below a certain threshold, the freediver would experience a temporary loss of psychomotor control accompanied by a sensation of weakness, trembling, blurred vision, and poor motor coordination. If in this phase the freediver did not start breathing again, for example following a prompt assistance, the freediver could suffer a serious syncope event, also called “black-out”, which causes the loss of consciousness and total inability to act. However, the human body reacts to a syncope with an extraordinarily fortunate response, i.e. by a laryngospasm that, by contacting the glottis, occludes the throat. This involuntary mechanism prevents the water entering the lungs and in fact prevents drowning. In this situation, the freediver can still be saved, for a very small number of minutes, before the lack of oxygen causes the main organs of the organisms to deteriorate with consequent and inevitable death. 
     It is thus clear how desirable it is to be able to measure the oxygen level in the blood of the freediver, both during the training phase in order to gain knowledge of the physical condition of the freediver and in order to improve continuously sporting performance, and during deep immersion in a natural environment in order to increase the safety of the freediver. 
     Devices are known that are suitable for measuring the level of oxygen saturation in the blood, which are also called oximeters or saturation meters or pulse oximeters when they also measure heartbeat. 
     As the most common commercial oximeter probes are applied to the index finger of the hand, it is clear that use thereof is greatly limited in all the human activities listed previously for which the hands are engaged in the activity. 
     In particular, during sleep, an oximeter probe positioned on the index finger will be subject to continuous and involuntary movements of the hand that would lead to errors in the reading of the plethysmographic signal. During the activities of operators in an environment that is hostile or lacking in oxygen such as firefighters and maintenance workers of cisterns, silos, conduits, mines, or operators exposed to a contaminated environment with a high chemical or biological risk, or operators operating at altitude or underwater, it is clear that an oximetry probe positioned on the index finger of the hand would make it difficult to perform any manual task, compromising the objectives of the professional activity. Similarly, during the sports activities disclosed above, as the hands are engaged in the sporting activity, the use of an oximetry probe positioned on the index finger would compromise correct performance of the sporting activity. 
     A particular mention must be made of aerodynamic sports such as for example parachuting and wingsuit flying, and of hydrodynamic sports such as for example swimming or scuba diving in apnoea. For such sports the hands and arms are used to maintain the aerodynamic and hydrodynamic position, so it is not possible to position any probe or instrument on a finger, on the wrist or on the arm because this would compromise the movement thereof, or the movement of the limbs would compromise correct measurement of the biomedical parameters. Further, any device provided with a display on the wrist would be impossible to read or display because such an operation would require the arm to be moved from the optimum position necessary for the aerodynamic or hydrodynamic setup. 
     OBJECTS OF THE INVENTION 
     One object of the present invention is to provide a face device for monitoring biomedical parameters of a user that enables the disclosed limits to be overcome. 
     A further object of the present invention is for the aforesaid face device to be able to communicate the biomedical data to the user without causing distractions to the user that may disturb the action of the user. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Such objects are achieved by a face device for monitoring biomedical parameters of a user in accordance with the first claim. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to better understand the invention, a description is given below of a series of non-limiting exemplary embodiments of the invention, which are illustrated in the attached drawings in which: 
         FIGS.  1 , 2    show the operating principle of the face device for monitoring biomedical parameters of a user, in accordance with the invention; 
         FIG.  3    is a block diagram that shows the structure and operation of the face device in accordance with the invention; 
         FIGS.  4 , 5 , 6    show a perspective view of a first embodiment of a face device according to the invention; 
         FIGS.  7 , 8 , 9    show a perspective view, a rear view, and a lateral section view, respectively, of a second embodiment of a face device according to the invention; 
         FIG.  10    shows two views, a perspective view and a lateral section view respectively, of a component of the face device of  FIGS.  7 - 9   ; 
         FIG.  11    shows two side views of the component of  FIG.  10   , illustrating the operating dynamic of the component; 
         FIGS.  12 , 13    show a perspective view, a front view and a side view of a third embodiment of a face device according to the invention; 
         FIGS.  14 , 15    show a perspective view of the face device of  FIGS.  12 , 13    associated with a diving mask; 
         FIGS.  16 , 17    show a perspective view of the face device of  FIGS.  12 , 13    associated with a gas mask; 
         FIGS.  18 , 19    show a perspective view, a front view and a side view of a fourth embodiment of a face device according to the invention; 
         FIGS.  20 , 21    show a perspective view of the face device of  FIGS.  18 , 19    associated with swimming goggles; 
         FIGS.  22 , 23    show a perspective view of the face device of  FIGS.  18 , 19    associated with a ski mask; 
         FIGS.  24 , 25    show a perspective view and a section plan view of a fifth embodiment of a face device according to the invention; 
         FIGS.  26 , 27    show a perspective view of the face device of  FIGS.  24 , 25    before and after placement on a user’s face; 
         FIGS.  28 , 29    show, each in a side, front and rear view, two components of the facial device of  FIGS.  24 , 25   ; 
         FIG.  30    shows an exploded perspective view of the aforesaid two components of the face device of  FIGS.  24 , 25   . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The illustrated face devices are able to measure heartbeat and oxygen saturation in the blood. 
     In particular, with regard to oxygen saturation in the blood, these devices enable the concentration of haemoglobin to be measured that, in this specific case, is linked to the oxygen. It is known that the haemoglobin bound to oxygen has a light absorption spectrum that is rather different from that of haemoglobin that is not bound and by measuring the plethysmographic signal, i.e. measurements of light absorption during volume variations of the blood vessels between the systolic phase, in which the heart compresses the blood in the arteries, and the diastolic phase, during which the heart relaxes, it is possible to calculate oxygen saturation in the blood. 
       FIG.  1    shows the diagram of the arterial system of the head  1  of a person, consisting of the carotid artery  2  that divides into the temporary artery  3  and into the facial artery  4 , in a symmetrical and specular manner both to the right and left of the face. In particular, it is clear that the facial artery  4  traverses the cheek spreading horizontally in a region of the face between the cheekbone and the nostril and vertically in the direction of the eye. 
       FIG.  2    shows the plethysmographic signals that are measured with an oximetry probe placed on the head  1  at the facial artery (A), of the eyebrow (B), of the forehead (C) and of the temporal artery (D), in rest conditions, at ambient temperature, at atmospheric pressure, and with the same instrument and person. These measurements show that the signal relating to the facial artery (A) is the widest signal. 
     The illustrated face devices all have an oximetry probe arranged at the facial artery  4  to measure in an optimum manner the heartbeat and oxygen saturation in the blood. 
       FIG.  3    shows the block diagram that is common to all the illustrated face devices, which shows the structure and operation thereof. Each face device has a support and housing structure, indicated by  5 . The structure  5  supports and contains an oximetry sensor  6 , a processing unit  7 , an interface assembly  8  and an energy storage unit  9 . The oximetry sensor  6  has a plurality of light sources at different wavelengths, for example light emission diodes, and a plurality of light sensors, for example photodiodes, an ambient light suppression circuit and an analogue-digital converter (ADC). The digital signal is processed by the processing unit  7  (MCU), which includes numeric low-pass and high-pass filters, or equivalently band-pass filters, that enable the direct-current (DC) and alternating-current (AC) component of the plethysmographic signal to be extracted. By measuring these values, it is possible to calculate heartbeat frequency, and the number of repetitions of the AC signal in the time unit, and oxygen saturation in the blood. The aforesaid biomedical parameters, heartbeat frequency and oxygen saturation in the blood, are communicated by the interface system  8  as a source of sounds and a plurality of light sources that are visible both from the inside and the outside of the mask. The aforesaid electronic components are supplied by the energy storage unit  9  so as to make each face device independent during the dive. 
       FIGS.  4 - 6    show a face device that is intended for applications in the sport area, in association with a diving mask  10 . The face device, indicated by  26 , has a body provided with two elastic extensions  27  connected by a bridge  28 , which is also elastic. The processing unit  7  is included in the body with the interfaces  8  and the energy storage unit  9 . The elastic extensions  27 , by expanding, press against the inner walls of the eye cavities of the diving mask  10 , maintaining the device  26  integral with the mask. In  FIGS.  4 , 5    two views of the device  26  are shown, in which are highlighted a first disc-shaped casing  29 , at the end of an elastic extension  27 , in which an oximetry sensor  30  is included and a second disc-shaped casing  31 , at the end of the other elastic extension  27 , in which a sound source  32  is included, for example an electromechanical bone conduction transducer. The aforesaid casings  29  and  31  are connected to the body of the device  26  by two elastic arms  33  that enable the oximetry sensor  30  and the sound source  32  to be maintained pressed at constant pressure onto the face of the diver. As shown better in  FIG.  6   , the device  26  is housed in the diving mask  10 , in such a manner that the oximetry sensor  29  is positioned at the facial artery  34  of the head  1  of the diver at constant pressure, to avoid false signals of the plethysmographic reading, more precisely in a region located horizontally between one of the two cheekbones and the nose and vertically below the eye. Similarly, the sound source  31  positions itself at the other cheekbone, indicated by  35 , of the head  1  of the diver at constant pressure, so that the acoustic signal can propagate through the bones of the cranium and be heard by the diver; in particular, the electromechanical transducer converts electric signals, corresponding to the sound to be transmitted, into mechanical vibrations to transmit the sound to the inner ear through the bones of the cranium. 
       FIGS.  7 - 9    show a face device that provides a protective face mask  36 , for example a diving mask, having a soft structure  37  that adapts to the face of the diver, a stiff structure or frame  38  that supports one or two windows of transparent material  39 , and one or more adjustable elastic straps  40  that secure the mask to the face of the diver. In this embodiment of the device, the soft structure  37  has, below one of the two windows  39 , a flexible extension  44  that contains an oximetry sensor  45 . Further, the soft structure  37  has, below the other of the two windows  39 , a flexible extension  24 , which is similar to the flexible extension  44 , that contains a sound source  25 , for example an electromechanical bone conduction transducer. The stiff structure  38  houses electronic boards  41  and  42 , on which both the processing unit  7  and the energy storage unit  9  are present, connected electrically to one another and to the oximetry sensor  45  and the sound source  25 . Also, the frame  38  contains one or more light sources  43  that are visible by other operators from the outside of the mask that can signal a risk situation for the health of the user. 
       FIG.  9    shows the positioning of the mask  36  on the head  1  of a user, for example a diver, according to the section in plane bb′ of  FIG.  8   . In particular, it is shown how the flexible extension  44  has an elastic arm  46  that maintains the oximetry sensor pressed against the face of the user, at the facial artery  47 , more precisely in a region located horizontally between the cheekbone and the nose and vertically below the eye, with an appropriate pressure. Excessive pressure would cause compression of the arterial vessels, and, on the other hand, insufficient pressure would cause empty spaces to be created, in both cases causing false optical signals and thus measuring errors. 
       FIG.  10    shows the detail of the flexible extension  44  with the oximetry sensor  45 , and in particular the connection of this flexible extension  44  with the edge of the soft structure  37  of the mask  36  through the elastic arm  46  is clearly visible. 
       FIG.  11    shows the operating dynamics of the flexible extension  44  and of the elastic arm thereof; in particular the flexible extension at rest ( 44   a  and  44   e , continuous line) is shown and on the other hand the flexible extension when it is subject to deformation caused by a push  48  ( 44   b  and  44   c , dashed line) and a twist  49  ( 44   d  and  44   f , dashed line) by the cheekbone of the user on the oximetry sensor. 
     During the dive, for example, because of the variation in water pressure but also because of the pressure variations due to the voluntary compensation of the diver, the mask  36  can vary the distance from the face of the diver. It is clear that owing to the shape and elasticity of the arm  46 , the oximetry sensor  45  remains positioned at the facial artery of the diver at constant pressure, avoiding false signals of the plethysmographic reading. 
     Similar technical considerations can apply to the flexible extension  24  containing the sound source  25 . 
     In  FIGS.  12 - 17    the device has the configuration of a soft face mask  49 , the latter having a casing made of elastic material, for example rubber, silicone, silicone rubber or any elastic polymer, or other, and of a moderate thickness (for example in the range between  1  and 3 mm), so as to be worn on the head  1  of a person and to adhere thanks to its elasticity to the person’s face. The mask  49  is supported by one or more appropriate straps  50  that are fastened behind the head  1 . This face mask  49  leaves the eyes and the nose uncovered by an opening  51  of a continuous face portion  52  of the casing (dashed line) that extends around the eyes, on the forehead and below the nose. The mask  49  is combinable with the diving mask  10  viewed previously and the continuous portion  52  of the mask  49  does not have any discontinuity along the surface and is able to ensure a hermetic seal between the mask  10  and the face of the user, as shown in  FIGS.  14 , 15   . Inside the casing of the mask  49 , included inside cavities of greater dimensions with respect to the rest of the face mask (for example in the range between  1  and 10 mm) an oximetry sensor  53  and a sound source  54  are housed, together with an electronic board  55 , including the processing unit  7  and the energy storage unit  9 . 
     In particular, the oximetry sensor  53  is positioned at the facial artery of the user at a constant pressure, avoiding false signals of the plethysmographic reading, more precisely in a region located horizontally between a cheekbone and the nose and vertically below the eye. Similarly, the sound source  54  is positioned at the other cheekbone of the user at a constant pressure, so that the acoustic signal can propagate through the bones of the cranium and be heard by the user. Both the oximetry sensor  53  and the sound source  54  are positioned inside or outside the continuous portion  52  so that the pressure thereof on the face is not affected by the involuntary movements of the mask. 
     In application use, for example for dives,  FIGS.  14 , 15    show the face mask  49  worn by a user on his head  1 , before and after wearing the diving mask  10 . The latter adheres perfectly to the face of the user owing to the fact that between the diving mask  10  and the face there is the continuous portion  52  of the face mask  49 , which does not have any discontinuity and ensures the hermetic seal from the surrounding environment. 
     For any use in hostile environments,  FIGS.  16 , 17    show the face mask  49  for measuring the oxygen saturation in the blood worn by a user on his head  1 , before and after wearing a protective face mask, which in this embodiment is a gas mask  20 . The latter adheres to the face of the user owing to the fact that between the gas mask  20  and the face there is the continuous portion  52  of the face mask  49 , which does not have any discontinuity and ensures the hermetic seal from the surrounding environment. 
       FIGS.  18 - 23    show a soft face mask  56  that is similar to the preceding mask  49 . 
     The mask  56  has a casing made of elastic material, for example rubber, silicone, silicone rubber or any elastic polymer, or other, and with a low thickness (for example in the range between  1  and 3 mm), so as to be worn on the head  1  of a person and to adhere thanks to its elasticity to the person’s face. The mask  56  is supported by one or more suitable straps  57  that are tied behind the head  1 . This face mask  56  leaves the eyes uncovered by two openings  58  of two continuous portions  59  of the casing around the eyes (dashed lines). Such a mask  56  is combinable with swimming goggles  63  and its continuous portions  59  do not have discontinuity along the surfaces thereof and are able to ensure the hermetic seal between the goggles  63  and the face of the user, as shown in  FIGS.  20 , 21   . Inside the casing, included inside cavities of greater dimensions with respect to the rest of the face mask (for example in the range between  1  and  10  mm), an oximetry sensor  60  and a sound source  61  are housed, together with an electronic board  62 , including the processing unit  7  and the energy storage unit  9 . 
     In particular, the oximetry sensor  60  is positioned at the facial artery of the user at a constant pressure avoiding false signals of the plethysmographic reading, more precisely in a region located horizontally between a cheekbone and the nose and vertically below the eye. Similarly, the sound source  61  is positioned at the other cheekbone of the user at constant pressure, so that the acoustic signal can propagate through the bones of the cranium and be heard by the user. Both the oximetry sensor  60  and the sound source  61  are positioned outside the continuous portions  58  so that the pressure thereof on the face is not affected by the involuntary movements of the mask or of the protective goggles. 
       FIGS.  20 , 21    show the face mask  56  worn by a user on his head  1 , before and after wearing the swimming goggles  63 . The latter adhere perfectly to the face of the user owing to the fact that between the swimming goggles and the face the continuous portions  59  of the face mask  56  are located that do not have any discontinuity and ensure the hermetic seal from the surrounding environment. 
     In application use in other sports such as for example parachuting, paragliding, wingsuit flying, mountaineering, freeclimbing, cycling, skiing, snowboarding, and the like, the mask  56  is combinable with a ski mask  64 .  FIGS.  22 , 23    show the mask  56  worn by a user on his head  1 , before and after wearing the mask  64 . This mask  64  is worn by the user above the face mask  56  owing to the fact that between the mask  64  and the face there are the continuous portions  59  of the face mask  56 . 
     Both in the face mask  49  and in the face mask  56 , the sound source can be an electromechanical bone conduction transducer. 
       FIG.  24    shows another embodiment of the facial device according to the invention. Also, in this case the device has the configuration of a soft mask  70  formed by a casing of elastic material provided with openings for the eyes and for the nose; in the example there are two eye openings  71  and a nasal opening  73 . The mask  70  is equipped with hooks  72  for straps and the like that keep the mask adherent to the user’s face thanks to the elasticity of the mask itself. The mask  70  is equipped with pockets  74  and  75  suitably shaped to removably accommodate an oximetry sensor  80  and a bone transducer  81  respectively. The pockets  74  and  75  have in this example a substantially “C” section profile. The mask  70  has a continuous front portion  76  in which the openings  71 ,  73  are obtained and which, thanks to its elasticity, guarantees tightness towards the external environment when a protective mask, such as a diving mask, a gas mask, ski goggles, and more, is applied to the facial device  70 . 
       FIG.  25    shows the substantially “C” section profile of the pockets  74  and  75 , which have openings  76  and  77  in the internal part of the mask which allow the oximetry sensor  80  and the bone transducer  81  to be inserted in a removable way. Other embodiments of the pockets may include for example magnetic connections, or undercut joints, or bayonet connections, or other types of connection which can ensure a secure bond of the oximetry sensor  80  and of the bone transducer  81  to the soft mask  70 . 
       FIG.  26    shows the position that the oximetry sensor  80  and the bone transducer  81  will assume respectively at the user’s facial artery and cheekbone. The oximetry sensor  80  and the bone transducer  81  will be inserted into the respective pockets  74  and  75  of the soft mask  70  before the latter is worn by the user. 
     On the other hand,  FIG.  27    shows the face mask  70 , with the oximetry sensor  80  and the bone transducer  81 , positioned on the face of the user  1  by means of suitable straps  78 . 
       FIG.  28    shows the detail of the oximetry sensor  80 , which has a rigid casing, where a,b,c respectively indicate a side view, the front view, and the rear view of this sensor. In general, a multisensory device can be provided which includes the oximetry sensor and other sensors such as cardiographic signal (ECG), electrical conductivity, depth, temperature, acceleration, geomagnetic, position (GPS), sound sensors, and other. The oximetry sensor  80  or the multisensory device may also include one or more energy storage units, rechargeable or not, a processing unit and a memory unit, and may further include a plurality of light or sound indicators, a radio transmitter and receiver unit, and more. In the illustrated example, a depth sensor  92 , an energy storage unit with charging contacts  88 , a processing unit with a memory unit, a control button  82  and warning lights  86  are provided incorporated in the oximetry sensor.  84  indicates a transparent optical window necessary to transmit the optical signals of the oximetry sensor. 
       FIG.  29    shows the detail of the bone transducer  81 , which has a rigid casing, where a,b,c respectively indicate a side view, the front view and the rear view of this transducer. Other sound sources can also be combined with the bone transducer  81 . The bone transducer  81  can also include one or more energy storage units, rechargeable or not, a signal amplifier, a processing unit, a memory unit, and can also include a plurality of light or sound indicators, a radio transmitter and receiver unit, and more. In the illustrated example, an energy storage unit with charging contacts  89 , a processing unit with a memory unit, a control button  83  and warning lights  87  are provided incorporated in the bone transducer  81 . With  85  the transduction membrane required to transmit the audio signal of the bone transducer is indicated. 
       FIG.  30    shows the details of the oximetry sensor  80  and of the bone transducer  81  previously described in  FIG.  28    and  FIG.  29    respectively. In particular, with regard to the oximetry sensor  80 , two parts  93  and  97  are highlighted that form the rigid casing of this sensor, the first of which integrates the transparent optical window  84  suitable for transmitting the optical signals of the oximetry sensor; on a support  95 , enclosed between the two parts  93  and  97 , the energy accumulator, an electronic board including the components of the sensors, the processing unit, the memory unit such as a solid-state memory unit, and the warning lights are mounted; any other components listed above can also be mounted on the support  95 . As regards the bone transducer  81 , two parts  94  and  98  are highlighted that form the rigid casing of this transducer, the first of which integrates the transduction membrane  85  suitable for transmitting the audio signal of the bone transducer; on a support  96  the energy accumulator, an electronic board including the signal amplifier, the processing unit, the memory unit, for example a solid-state memory unit, the warning lights are mounted; any other components listed above can also be mounted on the support  96 . 
     The oximetry sensor  80  and the bone transducer  81  are independent of each other but can also interact with each other, using radio transmitter and receiver units, in order to communicate information to the user based on the data collected by the different sensors and processed with deterministic programs but also based on learning algorithms. Always using radio transmitter and receiver units, the oximetry sensor  80  and the bone transducer  81  can also communicate with one or more external devices suitable for example to read or write data from or to each of them, to program or update the calculation program of processing units, or suitable for interacting in real time with the facial device. 
     The face masks  49 ,  56 ,  70  can also be used in the absence of any protective mask or goggles, in all the uses in which it is necessary to measure the biomedical parameters like heartbeat and oxygen saturation in the blood continuously and without hampering body movements, like for example:
     for oximetry measurements in intensive care both on health workers and patients, in particular in the case of epidemics;   during sleep for monitoring sleep apnea;   during professional activities that are critical for the health of the user;   in floor gymnastic disciplines.   

     The disclosed and illustrated face devices permit monitoring of biomedical parameters of a user without engaging the user in any manner. 
     Further, such face devices are able to communicate biomedical data to the user acoustically without causing distractions to the user that may disturb the actions of the user. 
     Variations can be made to both the general configuration and the configuration of the components of the illustrated face devices. 
     Other types of sensors can be provided that are incorporated into the face device to measure biomedical parameters such as body temperature sensors, arterial pressure sensors or other sensors. 
     Also, for the facial devices  26 ,  36 ,  49 ,  56  sensors can be provided for measuring operating parameters such as external temperature sensors, depth sensors, GPS, accelerometers or other sensors. 
     The face devices  26 ,  49 ,  56 ,  70  can be combined with any type of protective mask or protective goggles for any application.