GB2616852A - A Wireless Sensor Unit For Use In I Digital Stethoscope Sterilisation System - Google Patents

Abstract

A wireless sensor unit 101 has a primary microphone 124 electrically connected to a wireless transmitter 127 and enclosed within a fluid tight enclosure formed by a housing 103 comprising first housing part 105 with a diaphragm 117 and second housing part 107 attached together at a sealing interface 109,111 to form a smooth and continuous transitional region without recesses within which dirt or debris can collect and harbour bacteria or viruses. The front housing part 105 may be made from an acoustically dampening material, such as urethane rubber, which supports an amplification cone 121 having a secondary microphone 125 located in a secondary microphone recess 147 on its rear face 143.

Description

A Wireless Sensor Unit For Use In A Digital Stethoscope Sterilisation System A stethoscope is a relatively unusual medical instrument because unlike many other medical instruments it is not always subjected to a sterilisation procedure after each use.

Consequently, there are challenges associated with the use of stethoscopes in a way that is compliant with a stethoscope usage protocol, such as may be implemented in a clinical environment such as a hospital. Those challenges present themselves whether the stethoscope is an analogue stethoscope or a digital stethoscope.

1(:) At present, in clinical environments such as hospitals, stethoscopes are used in two ways. A clinician, for example a doctor, can have their own personal stethoscope which they use for all patients. It is the doctor's responsibility to maintain the cleanliness of their personal stethoscope such that the stethoscope is compliant with the stethoscope usage protocols that are in place. For example, it may be acceptable for the doctor to use their personal stethoscope for two or more patients without cleaning of the personal stethoscope between those patients, or it may be necessary for the doctor to clean, for example to sterilise, the stethoscope after every use, e.g. with an alcohol wipe, in order to comply with the stethoscope usage protocol. It can therefore be seen that a stethoscope usage protocol can contain rules that dictate that a stethoscope must be sterilised after every single use, i.e. so that the stethoscope is sterile and thus free from bacteria or from other living organisms. However, a stethoscope usage protocol can alternatively permit a stethoscope to be used on multiple occasions between sterilisation procedures, such that immediately in advance of being used with a patient the stethoscope is not necessarily sterile.

In the case of the use of a personal stethoscope, there is no way for the doctor, or for anyone else, to tell if the personal stethoscope is ready for use in compliance with a stethoscope usage protocol merely by looking at the stethoscope. If a doctor sterilises their personal stethoscope with an alcohol wipe then they will know that, at that particular moment in time, their personal stethoscope is sterile. If a doctor cleans their personal stethoscope at the end of a working day, and then puts it away in preparation for its next use, when the next working day arrives the doctor may or may not remember if their personal stethoscope is ready for use in compliance with a stethoscope usage protocol, for example that the stethoscope is in a sterile condition. If the doctor does not remember if their personal stethoscope is ready for use in compliance with a stethoscope usage protocol then they may sterilise it again. It can be considered that asking a doctor to be responsible for sterilising their personal stethoscope is not an efficient use of the doctor's time. If the doctor ends up unnecessarily duplicating a sterilisation operation, because they can't remember whether their personal stethoscope is ready for use in compliance with a stethoscope usage protocol, then this is an even less efficient use of the doctor's time. It should also be considered that the arrangements that are presently in use facilitate the possibility that a doctor may mistakenly believe that their personal stethoscope is ready for use in compliance with a stethoscope usage protocol, when in fact it is not. For example, this may occur if a doctor's usual routine is to sterilise their personal stethoscope before putting it away for future use but, for some reason, they forget to undertake the sterilisation procedure before they put it away.

Alternatively, a doctor can be issued with a disposable stethoscope which they use with just one patient before the disposable stethoscope is placed in a refuse bin for disposal. This approach addresses some of the above-mentioned problems, but it is not ideal, because a disposable stethoscope provides a lower level of performance than a doctor's personal stethoscope and because there is a large amount of waste associated with the use of disposable stethoscopes that are utilised only once before they are disposed of.

It should be noted that existing stethoscopes, whether digital or analogue, have external surfaces that are not smooth and continuous, but that have discontinuities such as result from ports, such as battery charging ports, and seams, for example seams produced during the manufacturing process. These ports, seams and any other recesses or protuberances of the external surface of the stethoscope facilitate the accumulation of dirt which can reduce the effectiveness of a sterilisation process. For example, wiping the external surface of the stethoscope with an alcohol wipe during a sterilisation process may not result in bacteria or other organisms within the dirt accumulation from being brought into contact with the alcohol, even if the surfaces of the dirt accumulations have been sterilised.

The present invention addresses the above-mentioned problems by providing a wireless sensor unit that can be used with a new system for sterilisation of digital stethoscopes. The wireless sensor unit can be informed about its sterilisation status, e.g. whether it is sterile or unsterile, and can pass that sterilisation status on to a user. Consequently, the user will always know whether the sensor unit is available for use, for example in proper accordance with a hospital's stethoscope usage protocol, or whether the sensor unit needs to be sterilised before its next use.

According to the present invention there is provided a wireless sensor unit having a microphone and a wireless transmitter enclosed within a liquid tight enclosure formed by a housing, wherein the housing comprises a first housing part attached to a second housing part at a sealing interface, wherein the sealing interface is located between a first attachment surface on the first housing part and a second attachment surface on the second housing part, and wherein the housing has a transitional region of its external surface that extends from the first housing part across the sealing interface to the second housing part, and the cross-sectional profile of the transitional region is smooth and continuous, wherein the first housing part has an external wall comprising a diaphragm, wherein the digital microphone is arranged so that, in use, at least part of the microphone will vibrate in response to vibrations of the diaphragm and will produce sound data and the digital microphone and the wireless transmitter are electrically connected together so that the wireless transmitter can transmit the sound data. Providing the housing with a smooth and continuous transitional region, for io example a region without any ports, seams and any other recesses or protuberances, is advantageous, because the external surface of the wireless sensor unit can avoid being susceptible to accumulations of dirt which can reduce the effectiveness of a sterilisation process, as explained above.

Preferably, the second housing part has an external wall with an uninterrupted external surface.

Preferably, the wireless sensor unit further comprises an amplification cone located within the housing and aligned with the diaphragm, so that, in use of the wireless sensor unit, sound waves generated by the diaphragm enter the amplification cone and are passed to the digital microphone, wherein the housing comprises a rigid support and the amplification cone is held within the housing by a cone support member made from an acoustic dampening material, wherein the cone support member is attached to the amplification cone and to the rigid support and the cone support member is located between the amplification cone and the rigid support.

Preferably, the first housing part is made of an acoustic dampening material and provides the cone support member and the second housing part comprises the rigid support and is made of a shock resistant material.

Preferably, the first housing part is rigid and the rigid support is part of the first housing part, and wherein the cone support member is made from an acoustically dampening material and is located between the amplification cone and the rigid support. For example, the cone support member could be an annular ring made from a urethane rubber and the annular ring could be located within the housing and positioned between the internal wall of the front housing part and the external wall of the amplification cone. The annular ring would be attached to the front housing part and the amplification cone to hold the amplification cone in place within the housing and to act as a damping member.

Preferably, the external wall of the first housing part is a cup-shaped external wall and is provided with a diaphragm aperture in the closed end of the cup-shaped external wall, into which the diaphragm is attached in a manner such that, in cross-section, the profile of the first housing part is smooth and continuous between the cup-shaped external wall and the diaphragm, wherein the cone support member forms part of the cup-shaped external wall, and wherein the open end of the cup-shaped external wall provides the first attachment surface, and wherein the second housing part also has a cup-shaped external wall and the open end of the cup-shaped external wall provides the rear attachment surface.

Preferably, the external wall of the first housing part is made from an acoustic dampening material and the acoustic dampening material isolates the diaphragm from the second housing part.

Preferably, the wireless sensor unit further comprises an acoustic dampening interface component located between the diaphragm and the first housing part.

Preferably, the microphone and the wireless transmitter are located between the rear of the amplification cone and the bottom of the cup of the cup-shaped external wall of the second housing part.

Preferably, the wireless sensor unit further comprises an electrical power storage device and a wireless charging coil for wirelessly charging the electrical power storage device. The wireless charging coil may be a copper trace located on the internal or external face of the 25 diaphragm.

Preferably, the second housing part is provided with a flat rear surface and the wireless charging coil is located within the housing and adjacent to the flat rear surface.

Preferably, the wireless sensor unit comprises a second microphone located adjacent to a microphone recess provided within the amplification cone, wherein the microphone recess is not open to the cone of the amplification cone.

Preferably, the housing is generally cylindrical, the first housing part is in the form of an annular ring, with the diaphragm aperture located adjacent to a front side of the annular ring, wherein the cone support member is formed integrally with the annular ring, and the second housing part is a shallow circular cup, wherein the first attachment surface is provided at least in part on a rear facing end face of the annular ring of the first housing part and the second attachment surface is provided at least in part on a front facing end face of the shallow circular cup of the second housing part.

Preferably, the amplification cone is generally cylindrical with a flat rear face parallel to a flat front face, wherein the flat front face is annular and located around the front opening to the amplification cone, the amplification cone also having an external side wall provided with an attachment feature for attachment to the cone support member.

Preferably, a separation space is provided between the amplification cone and the internal wall of the annular ring.

Preferably, a rearward facing side of the housing is provided with a flat surface that is parallel to the diaphragm Preferably, the second housing part is made of a rigid polymer, for example, acrylonitrile butadiene styrene (ABS), and the first housing part is made of a readily deformable polymer, for example, a urethane rubber.

In an alternative embodiment of the present invention the microphone is located on the diaphragm.

In one embodiment of the present invention, the microphone is a digital microphone that, through signal processing, produces a digital output.

In an alternative embodiment of the present invention, the microphone is an analogue microphone that produces a digital output.

Preferably, the first housing part is attached to the second housing part by a hard-setting adhesive, wherein the adhesive adheres the first attachment surface to the second attachment surface to create the sealing interface.

The present invention will be described here with reference to the following figures: Figure 1 is a schematic view of the digital stethoscope system including the wireless sensor unit; Figure 2 is a top perspective view of a first embodiment of a wireless sensor unit; Figure 3 is a bottom perspective view of the first embodiment of the wireless sensor unit as illustrated in Figure 2; Figure 4 is a cross-sectional view through the wireless sensor unit; Figure 5 is a cross-sectional view through the front housing part of the wireless sensor unit; tip Figure 6 is a perspective view of the inside of the rear housing part of the wireless sensor unit; Figure 7 is a bottom perspective view of the amplification cone of the wireless sensor unit of Figure 1; Figure 8 is a top perspective view of the amplification cone; and Figure 9 is a schematic representation of a digital stethoscope sterilisation system An embodiment of a digital stethoscope system 1 according to the present invention is shown in Figure 1. The digital stethoscope system 1 comprises a wireless sensor unit 101, wirelessly connected to other components of the digital stethoscope system 1 in order to wirelessly transmit or receive digital information, such as sound data, to or from one or more of the other components. The other components are a pair of headphones 3, a smartphone 5, a bespoke display device 7, a data processing unit 9, a data storage device 11 and a wireless charging pad 13.

The sensor unit 101 is wirelessly connected to the other components of the wireless digital stethoscope system using any means that is suitable for the transmission of digital information. For example, Bluetooth® can be used.

In one mode of use of the present invention, the digital stethoscope system 1 operates merely as a digital stethoscope. A clinician uses the sensor unit 101 connected to a pair of headphones 3 to listen to sounds from a patient, in real time. If the clinician wishes to see a visual representation of the sounds then that can be provided by the visual display. The digital stethoscope system can also process, analyse and display the data associated with those sounds.

A first embodiment of a wireless sensor unit 101 according to the present invention is shown in Figures 2 and 3. The wireless sensor unit 101 comprises a two-part housing 103 having a front housing part 105 that in use is located closest to the patient and a rear housing part 107 that is located on the other side of the wireless sensor unit 101. The front housing part 105 is in the form of a circular annular ring, which is shown in cross-section in Figure 5. The rear housing part 107 is circular in cross-section and cup-shaped, having an open end and a closed end, as shown in Figure 6.

The front housing part 105 and the rear housing part 107 are attached to each other. The front to housing part 105 is provided with an inner attachment surface 109 on its rearwardly directed end face. The rear housing part 107 is provided with an outer attachment surface 111 on its inner surface that is adjacent to its forwardly directed end face. The inner attachment surface 109 and the outer attachment surface 111 have complementary profiles and provide surfaces to which an epoxy resin adhesive can bond in order to attach the front housing part 105 to the rear housing part 107 in a fluid-tight manner.

The front housing part 105 is provided with a circular diaphragm aperture 113 in a circular diaphragm recess 115 that is provided at the front side of the front housing part 105. A circular diaphragm 117 is bonded into the diaphragm recess 115. The combination of the diaphragm 117, the front housing part 105 and the rear housing part 107 form a hollow body which is fluid tight. The term fluid tight is used here to mean that liquids and dirt, such as dust, cannot pass into or out of the body.

An interior space 119 is created within the hollow body of the wireless sensor unit 101. The interior space 119 is generally cylindrical and contains an amplification cone 121, an electrical printed circuit board 123, a primary microphone 124, a secondary microphone 125, an electrical battery 126, a wireless receiver and transmitter 127 and a wireless charging coil 129.

The front housing part 105 is made from an acoustically dampening material, such as urethane rubber. An annular cone retention lip 131 is provided on the front housing part 105 and it is located co-axially with and parallel to the diaphragm recess 115. A cone body space 133 is provided rearwardly of the cone retention lip 131 in order to accommodate the amplification cone 121.

The diaphragm 117 is located in the diaphragm aperture 113 provided in the front housing part 105. The front housing part 105 therefore acts as an acoustic damper between the diaphragm 117 and the rear housing part 107, and therefore damps any vibrations emanating from the rear housing part 107, for example from the rear housing part 107 being brushed against an item of clothing.

The amplification cone 121 is located within the front housing part 105 and connected to it by engagement of the cone retention lip 131 with a cone retention recess 135 on the amplification cone 121. The amplification cone 121 is a close fit within the front housing part 105 so that there is only a small annular cone clearance space 137 between the amplification cone 121 and the front housing part 105. It is advantageous for the annular cone clearance space 137 to be small because this facilitates maximisation of the size of the amplification cone 121, and therefore the mass of the amplification cone 121, within the constraints imposed by the internal volume of the two-part housing 103 and the other components contained therein. The purpose of the annular cone clearance space 137 is to reduce the amount of the surface of the amplification cone 121 that is in contact with the two-part housing 103, such that the amount of vibration transmitted from the two-part housing 103 to the amplification cone 121 is is minimised.

The amplification cone 121 is shown in greater detail in Figures 7 and 8. It is generally cylindrical, with a large diameter relative to its height, and is provided with a conical recess 139 that is located co-axially with the longitudinal axis of the amplification cone 121. In addition to the conical recess 139, other recess shapes are envisaged, such as recesses that have parabolic profiles. The wide end of the conical recess 139 starts at the front cone face 141 of the amplification cone 121 and extends rearwardly, so that the apex of the conical recess 139 is located on the longitudinal axis of the amplification cone 121, and a short distance in front of the rear cone face 143 of the amplification cone 121. A tubular apex aperture 145 passes between the apex of the conical recess 139 and the rear cone face 143. The rear cone face 143 is flat and is parallel to the front cone face 141. A secondary microphone recess 147 is located on the rear cone face 143 and extends towards the wall of the conical recess 139, but does not contact that wall. The secondary microphone 125 is located adjacent to the secondary microphone recess 147, such that the sound port of the secondary microphone 125 faces into the secondary microphone recess 147, such that the secondary microphone 125 and the secondary microphone recess 147 are linked in a way that facilitates the secondary microphone 125 to sense sounds from the secondary microphone recess 147.

When the amplification cone 121 is positioned within the wireless sensor unit 101 and when it is attached to the front housing part 105 by engagement of the cone retention lip 131 and the cone retention recess 135, the rear cone face 143 is parallel to and co-axial with the circular diaphragm 117.

The printed circuit board 123 is located adjacent to the rear cone face 143 and a microphone aperture 149 passes through the printed circuit board 123 and is aligned with the apex aperture 145. The primary microphone 124 is located adjacent to the rearward opening of the microphone aperture 149. The battery 126 is also located on the rear cone face 143.

The wireless receiver and transmitter 127 is attached to the inside of the rear housing part 107. The bottom of the cup of the cup-shaped rear housing part 107 is provided with a flat surface with an internal interface surface 151 and an external locating surface 153. The internal interface surface 151 and the external locating surface 153 are parallel to each other and to the diaphragm 117.

The wireless charging coil 129 is also provided adjacent to the internal interface surface 151.

The primary microphone 124, the secondary microphone 125, the battery 126, the wireless receiver and transmitter 127, the wireless charging coil 129 and the electrical circuitry provided on the printed circuit board 123 are electrically connected together.

The front housing part 105, the rear housing part 107 and the diaphragm 117 create a fluid tight body that does not have any recesses within which dirt or debris can collect and harbour bacteria or viruses. In order to create a wireless sensor unit 101 without any recesses the epoxy resin adhesive that is used to bond the front housing part 105 to the rear housing part 107 is applied in a quantity such that it completely fills the joint at the interface between the front housing part 105 and the rear housing part 107 and such that it extends above the external surfaces of the front housing part 105 and rear housing part 107 to create an annular bead of epoxy resin adhesive around the wireless sensor unit 101. The annular bead of epoxy resin adhesive can be polished back after it has cured, so that the wireless sensor unit 101 has a smooth transitional zone between the front housing part 105 and the rear housing part 107 which is flush with their external surfaces, wherein that transitional zone has no recesses within which dirt or debris can collect. Similarly, the diaphragm 117 is bonded into the diaphragm aperture 113 by an epoxy resin adhesive. The epoxy resin adhesive is applied so that it completely fills any gaps between the edges of the diaphragm aperture 113 and the diaphragm 117 and such that it extends above the external surfaces of the front housing part 105 to create an annular bead of epoxy resin adhesive around the diaphragm 117 that can be polished back after it has cured, so that the wireless sensor unit 101 has a smooth transitional zone between diaphragm 117 and the front housing part 105, wherein that transitional zone has no recesses within which dirt or debris can collect.

The wireless sensor unit 101 is also provided with a indicator lamp 155 that can provide illumination in two or more colours, for example red and green. The indicator lamp 155 is located inside the two-part housing 103 and the illumination from the indicator lamp 155 can be seen through the rear housing part 107, for example by making the rear housing part 107 opaque, or by providing an aperture through the wall of the rear housing party 107 into which the indicator lamp 155 can be fitted (in a manner, such as described above in relation to the diaphragm 117, that avoids any dirt or debris collecting recesses between the indicator lamp 155 and the external surface of the rear housing part 107).

In use, the wireless sensor unit 101 forms part of a digital stethoscope sterilisation system 201, as illustrated in Figure 9, which facilitates use of a wireless sensor unit 1 in accordance with a stethoscope usage protocol as may be set by a hospital. The digital stethoscope sterilisation system 201 comprises a sensor unit sterile store 203, a sensor unit collection receptable 205 and a sensor unit sterilisation station 207. The sensor unit sterile store 203 is a box with an openable lid, which is provided with a wireless charging pad 13. A number of wireless sensor units 101 are stored within the sensor unit sterile store 203 in a way such that the battery 126 within each wireless sensor unit 101 is charged by the wireless charging pad 203 whilst the wireless sensor unit 101 is in storage and waiting to be issued. The sensor unit collection receptacle 205 is a cylindrical bin with a sealed lid provided with a slot 209 dimensioned to permit a wireless sensor unit 101 to pass through it. The sensor unit sterilisation station 207 contains means, such as an alcohol wipe cleaning system, for sterilising the wireless sensor units 101.

In an alternative embodiment of the invention, which is not illustrated, the rear housing part of a two-part housing can be made from a thermoplastic polymer material and during assembly the rear housing part can be locally heated to permit the front housing part to be pressed into the rear housing part to form a fluid tight enclosure. Any flashing created during assembly can then be cut and/or polished away so that there is a smooth transitional zone between the front and rear housing parts. It is also envisaged that the front housing part and the rear housing part can be attached together by ultrasonic welding to form a fluid tight enclosure. Again, any flashing created during assembly can then be cut and/or polished away so that there is a smooth transitional zone between the front and rear housing parts.

The digital stethoscope sterilisation system 201 works by storing the wireless sensor units 101 in the sensor unit sterile store 203 in a sterile state, ready to be issued on demand.

When the wireless sensor unit 101 is placed in the sensor unit sterile store 203 the digital stethoscope sterilisation system 201 places it in a first status called IN STERILE STORAGE AND READY FOR USE'. If a doctor wants a wireless sensor unit 101 then they go to the sensor unit sterile store 203 and are issued with one. The doctor knows that the wireless sensor unit 101 is sterile, because they have seen it being issued from the sensor unit sterile store 203. A further indication that the wireless sensor unit 101 is sterile can be provided to the doctor by the wireless sensor unit 101, for example the indicator lamp 155 can be illuminated in green (the doctor having been advised during training that the wireless sensor tip unit 101 is sterile when the indicator lamp is illuminated in green). The digital stethoscope sterilisation system 201 can also issue an audible notification to the doctor that the wireless sensor unit 101 is sterile, for example via the pair of headphones 3.

Once the wireless sensor unit 101 has been issued from the sensor unit sterile store 203 the digital stethoscope sterilisation system 201 places it into a second status called 'IN USE'. The doctor uses the wireless sensor unit 101 with one or more patients whilst the wireless sensor unit 101 is considered to be in an 'IN USE' state, i.e. in a state suitable for use in accordance with the stethoscope usage protocol in place in the particular clinical environment. That stethoscope usage protocol may dictate that the wireless sensor unit 101 may be 'IN USE' for one patient only, or it may be 'IN USE' for multiple patients.

Once the wireless sensor unit 101 can no longer be used in accordance with the stethoscope usage protocol the digital stethoscope sterilisation system 201 places it into a third status called 'OUT OF USE'. Once the wireless sensor unit 101 is in the 'OUT OF USE' state it will no longer function as required, for example it will no longer make sound data from a patient available to the doctor. The wireless sensor unit 101 can give an indication to the doctor that it is no longer available for use, for example the indicator lamp 155 can be illuminated in red (the doctor having been advised during training that when the indicator lamp is illuminated in red the wireless sensor unit 101 is no longer available for use). The status of the wireless sensor unit 101 can be changed from 'IN USE' to 'OUT OF USE' in a number of ways. The doctor can change the status to 'OUT OF USE' themselves, for example by using a smartphone app to communicate via Bluetoothe with the wireless sensor unit 101. The status can be changed once the wireless sensor unit 101 has been removed from the sensor unit sterile store 203 for a pre-determined period of time, for example for one hour, or the status can be changed if the wireless sensor unit 101 has been moved away from the sensor unit sterile store 203 by a distance that exceeds a threshold distance.

In order to place the wireless sensor unit 101 back into a state where it is available for use, i.e. to change the status of the wireless sensor unit 101 from 'OUT OF USE' to 'IN USE', the doctor needs to submit the wireless sensor unit 101 for sterilisation and subsequent storage.

The doctor places the wireless sensor unit 101 into a sensor unit collection receptacle 205, whereby the digital stethoscope sterilisation system 201 changes the status of the wireless sensor unit 101 to a fourth status called 'AWAITING COLLECTION FOR STERILISATION'. The wireless sensor unit 101 and the sensor unit collection receptacle 205 can communicate with each other, such that the digital stethoscope sterilisation system 201 can be informed that ic) the wireless sensor unit 101 is ready to be collected for sterilisation. A Bluetooth® or Near Field Communication (NFC) system can be employed for communication of the wireless sensor unit 101 and the sensor unit collection receptacle 205. A NFC system will know if the wireless sensor unit 101 is within the sensor unit collection receptacle 205, because the NFC system is only operational over a short distance, for example 4cm. A Bluetooth® system will is know the distance of the wireless sensor unit 101 from the sensor unit collection receptacle 205 and if that is distance is lower than a pre-determined distance the wireless sensor unit 101 will be recorded as having been deposited within the sensor unit collection receptacle 205. The wireless sensor units 101 can be collected from the sensor unit collection receptacle 205 at any appropriate time, for example when the number of wireless sensor units 101 exceeds a threshold number.

It is envisaged that the digital stethoscope sterilisation system 201 could operate without placing the wireless sensor unit 101 into the fourth status. In an alternative method, once the wireless sensor unit 101 has been placed into the third status, such that it is designated as being OUT OF USE', the wireless sensor unit 101 could send a message to the digital stethoscope sterilisation system 201 stating that it needs to be sterilised.

When the digital stethoscope sterilisation system 201 deems it appropriate, for example when a certain number of wireless sensor units 101 have been placed into the sensor unit collection receptacle 205, the wireless sensor unit 101 is collected and taken to the sensor unit sterilisation station 207 for sterilisation. When the wireless sensor unit 101 is placed within the sensor unit sterilisation station 207 the digital stethoscope sterilisation system 201 changes its status to a fifth status called 'BEING STERILISED'. Sterilisation of the wireless sensor unit 101 occurs by, for example, being wiped with an alcohol wipe by a member of hospital staff tasked with cleaning the wireless sensor units 101. The wireless sensor unit 101 can identify itself to the hospital staff member cleaning it (or to the digital stethoscope sterilisation system 201), using a unique identification number. The seamless nature of the design of the wireless sensor unit 101 facilitates a straightforward sterilisation process, for example, because of the recess free design that obviates the need for any scrubbing to remove dirt or debris acquired in use.

It is envisaged that the digital stethoscope sterilisation system 201 could operate without placing the wireless sensor unit 101 into the fifth status. In an alternative method, once the wireless sensor unit 101 has been sterilised its status can be changed from the third status of 'OUT OF USE' to the first status of 'IN STERILE STORAGE AND READY FOR USE'.

Once sterilised, the wireless sensor unit 101 is moved from the sensor unit sterilisation station 207 to the sensor unit sterile store 203 and the digital stethoscope sterilisation system 201 changes its status back to the first status in the cycle, i.e. 'IN STERILE STORAGE AND READY FOR USE'. This status change can be undertaken automatically, e.g. as a result of the sensor unit sterile store 203 detecting the presence of the wireless sensor unit 101 and detecting that the wireless sensor unit 101 is in the fourth status. Alternatively, a duly authorised and identified member of hospital staff can submit the wireless sensor unit 101 to a device that will change the status. If the battery 126 in the wireless sensor unit 101 needs to be charged then that charging can take place using the wireless charging pad 13.

A wireless sensor unit 101 moves through the sterilisation cycle multiple times during its working life. The digital stethoscope sterilisation system 201 detects each time a wireless sensor unit 101 passes through the sterilisation cycle and keeps a record of the total number of times the wireless sensor unit 101 has passed through a sterilisation cycle. Once a wireless sensor unit 101 has reached a maximum number of allowable cycles it can be taken out of use, for disposal or recycling, and replaced with a new wireless sensor unit 101. The maximum number of allowable cycles can be determined by various operational parameters, such as how many times the battery has been recharged.

In this way, the digital stethoscope sterilisation system 201 can provide at any one time multiple wireless sensor units 101 in a sterile state ready for use by a doctor and can put used wireless sensor units 101 through a collection and sterilisation cycle efficiently, so that the wireless sensor units 101 can be made available for issuance to a doctor as quickly as possible.

Claims (21)

1. CLAIMS1. A wireless sensor unit (101) having a microphone (124) and a wireless transmitter (127) enclosed within a liquid tight enclosure formed by a housing (103), wherein the housing (103) comprises a first housing part (105) attached to a second housing part (107) at a sealing interface, wherein the sealing interface is located between a first attachment surface (109) on the first housing part (105) and a second attachment surface (111) on the second housing part (107), and wherein the housing (103) has a transitional region of its external surface that extends from the first housing part (105) across the sealing to interface to the second housing part (107), and the cross-sectional profile of the transitional region is smooth and continuous, wherein the first housing part (105) has an external wall comprising a diaphragm (117), wherein the microphone (124) is arranged so that, in use, at least part of the microphone (124) will vibrate in response to vibrations of the diaphragm (117) and will produce sound data and the microphone (124) and the wireless transmitter (127) are electrically connected together so that the wireless transmitter (127) can transmit the sound data.
2. A wireless sensor unit (101) as claimed in claim 1, wherein the second housing part (107) has an external wall with an uninterrupted external surface.
3. 3. A wireless sensor unit (101) as claimed in claim 1 or claim 2, further comprising an amplification cone (121) located within the housing (103) and aligned with the diaphragm (117), so that, in use of the wireless sensor unit (101), sound waves generated by the diaphragm (117) enter the amplification cone (121) and are passed to the microphone (124), wherein the housing (103) comprises a rigid support (107) and the amplification cone (121) is held within the housing (103) by a cone support member (105) made from an acoustic dampening material, wherein the cone support member (105) is attached to the amplification cone (121) and to the rigid support (107) and the cone support member (105) is located between the amplification cone (121) and the rigid support (107).
4. A wireless sensor unit (101) as claimed in claim 3, wherein the first housing part (105) is made of an acoustic dampening material and provides the cone support member (105) and the second housing part (107) comprises the rigid support (107) and is made of a shock resistant material.
5. 5. A wireless sensor unit (101) as claimed in claim 3, wherein the first housing part (105) is rigid and the rigid support (105) is part of the first housing part (105), and wherein the cone support member is made from an acoustically dampening material and is located between the amplification cone (121) and the rigid support (105).
6. 6. A wireless sensor unit (101) as claimed in any of claims 3 to 5, wherein the external wall of the first housing part (105) is a cup-shaped external wall and is provided with a diaphragm aperture (113) in the closed end of the cup-shaped external wall, into which the diaphragm (117) is attached in a manner such that, in cross-section, the profile of the first housing part (105) is smooth and continuous between the cup-shaped external wall and the diaphragm (117), wherein the cone support member forms part of the cup-shaped external wall, and wherein the open end of the cup-shaped external wall provides the first attachment surface (109), and wherein the second housing part (107) also has a cup-shaped external wall and the open end of the cup-shaped external wall provides the rear attachment surface (111). 7. 8. 9. 12.
7. A wireless sensor unit (101) as claimed in claim 6, wherein the external wall of the first housing part (105) is made from an acoustic dampening material and the acoustic dampening material isolates the diaphragm (117) from the second housing part (107).
8. A wireless sensor unit (101) as claimed in claim 6, further comprising an acoustic dampening interface component located between the diaphragm (117) and the first housing part (105).
9. A wireless sensor unit (101) as claimed in any of claims 6 to 8, wherein the microphone (124) and the wireless transmitter (127) are located between the rear of the amplification cone (121) and the bottom of the cup of the cup-shaped external wall of the second housing part (107).
10. A wireless sensor unit (101) as claimed in any preceding claim, further comprising an electrical power storage device (126) and a wireless charging coil (129) for wirelessly charging the electrical power storage device (126).
11. A wireless sensor unit (101) as claimed in claim 10 wherein the second housing part (107) is provided with a flat rear surface and the wireless charging coil (129) is located within the housing (103) and adjacent to the flat rear surface.
12. A wireless sensor unit (101) as claimed in any of claims 2 to 7, comprising a second microphone (125) located adjacent to a microphone recess (147) provided within the amplification cone (121), wherein the microphone recess (147) is not open to the cone (139) of the amplification cone (121).
13. 13 A wireless sensor unit (101) as claimed in any of claims 6 to 12, wherein the housing (103) is generally cylindrical, the first housing part (105) is in the form of an annular ring, with the diaphragm aperture (113) located adjacent to a front side of the annular ring, wherein the cone support member is formed integrally with the annular ring, and the second housing part (107) is a shallow circular cup, wherein the first attachment surface (109) is provided at least in part on a rear facing end face of the annular ring of the first tip housing part (105) and the second attachment surface (111) is provided at least in part on a front facing end face of the shallow circular cup of the second housing part (107).
14. 14 A wireless sensor unit (101) as claimed in claim 13, wherein the amplification cone (121) is generally cylindrical with a flat rear face (143) parallel to a flat front face (141), wherein the flat front face (141) is annular and located around the front opening to the amplification cone (121), the amplification cone (121) also having an external side wall provided with an attachment feature (135) for attachment to the cone support member.
15. 15. A wireless sensor unit (101) as claimed in claim 14, wherein a separation space is provided between the amplification cone (121) and the internal wall of the annular ring.
16. 16 A wireless sensor unit (101) as claimed in any preceding claim wherein a rearward facing side of the housing (103) is provided with a flat surface that is parallel to the diaphragm (117).
17. 17 A wireless sensor unit (101) as claimed in any preceding claim, wherein the second housing part (107) is made of a rigid polymer, for example, acrylonitrile butadiene styrene (ABS), and the first housing part (105) is made of a readily deformable polymer, for example, a urethane rubber.
18. 18. A wireless sensor unit (101) as claimed in claim 1 or claim 2, wherein the microphone (124) is located on the diaphragm.
19. 19. A wireless sensor unit (101) as claimed in any preceding claim, wherein the microphone (124) is a digital microphone (124) that produces a digital output.
20. A wireless sensor unit (101) as claimed in any of claims 1 to 18, wherein the microphone (124) is an analogue microphone (124) that, through signal processing, produces a digital output.
21. 21 A wireless sensor unit (101) as claimed in any preceding claim, wherein the first housing part (105) is attached to the second housing part (107) by a hard-setting adhesive, wherein the adhesive adheres the first attachment surface (109) to the second attachment surface (111) to create the sealing interface.