The present invention relates to a modelling device made of an elastic or plastic material which may adapt to a shape of a body surface or a body part such as a residual limb of an amputee. The purpose of the modelling device is to obtain data reflecting the exterior geometric shape and optionally tissue density of the body surface or body part.

The obtained data may be utilized to generate a three-dimensional model and optionally identify areas of hard or soft tissue of a body surface.

The resulting model and associated tissue data may be used to create a device embracing the form and shape of the body surface or body part such as a prosthesis or an orthosis with improved fit in terms of both shape and comfort.

Background of the invention

It is known to prepare prosthetic/orthotic devices by making a cast or by picturing a residual stump and from this cast or pictures prepare a prosthetic/orthotic device with a size corresponding to the cast or the pictures. However, these procedures are normally demanding on resources and time.

WO 2007/144608 discloses a method for determining a 3D imaging of a residual limb and for the design of prostheses and orthoses. A probe comprising load cell (102) is mounted behind an ultrasound transducer (104). A computer (108) determines and displays the position (112) of a boundary in the medium using conventional ultrasonic scanning techniques. The computer (108) determines the strain (114) at the boundary using two or more measured positions of the boundary. The computer (108) determines the stress (116) at the boundary using the load and position of the boundary and using a model (118) of the propagation through the medium of the pressure wave imparted by the probe. For scanning a residual limb, the probe is mounted in a scanner (302) and rotated around the limb and dragged across its surface or mounted in a glove (402) or sock (502). However, the probes (504) according to this document are not capable of producing a force identifying hard and soft tissue. The probes (504) are also not capable of generating external geometric data of the residual limb based on their relative positions, instead, a laser scan captures the 3-dimensional external geometry of the residual limb. US 2019/0038374 A1 discloses a bio-sensor strip adapted to be located between an object and a body part. The bio-sensor strip comprises one or more of biosensors (819, 919) disposed on at least one first polymer film (825), wherein the biosensors (819, 919) measure parameters at a location between the object (216, 316, 916) and the body part (932). However, the biosensors 919 according to this document are not located on a modelling device covering a residual limb, and the biosensors are not capable of generating external geometric data based on their relative positions. According to this document it is necessary to utilize a camera and laser system to generate a 3D model of a limb.

US 2017/0333223 A1 discloses use of Electro Active Polymers (EAPs) contracting and expanding at low voltages to provide for a shape-morphing system, such as a prosthetic liner, and potentially entire prosthetic socket, to contract and expand in strategic areas as needed to maintain a comfortable fit throughout the day. In some embodiments, as the residual limb changes, these novel robust EAPs can change dynamically as needed to maintain a comfortable, snug fit of the prosthetic liner or socket with the hard shell of the prosthetic socket device. In some embodiments, the EAPs used in prosthetic liners or sockets may also detect pressure during use, and automatically adjust to maintain fit through a control unit, so that the person does not even have to stop and adjust the device during an active day. However, the system is not capable of determining tissue density based on actuation of the electroactive polymer material. Even if the shape morphing sheets could be said to be pressure sensors, the material does not appear to be capable of providing data that could be used to generate a 3D model based on the relative positions of the sheets. The shape-morphing is not directed to geometric or tissue density measurement.

WO 2020074374 discloses a modelling device (1) for creating a 3-dimensional surface model of a body surface or body part, which device comprises or is constituted of an elastic or plastic material configured for tight fitting to a body surface or a body part, and the modelling device comprises: a plurality of position sensors (6) distributed along a surface of the modelling device where each position sensor or a part of a position sensor can measure and define its position relative to one or more neighbouring position sensors. Each position sensor or a group of position sensor comprises a transmitter configured to transmit position data to a receiver during use (different embodiments disclose different solutions of transmitting the position data, e.g., from position sensor (22) via electrical connections (24) is transmitted to the distal end (8) and on to the processing device (12)). The subject matter of the present invention differs from this document in that, W02020074373 does not disclose one position sensor having both an active and a passive state and how to measure variation of physical dimensions and density of a body surface in one procedural step when constructing a 3D-model of the body surface.

Summary of the invention

Thus, an object of the present invention relates to a method and a device providing improved fit in terms of both shape and comfort embracing the form and shape of a body surface or body part, the method and device may be used to provide any kind of outer support (orthosis) such as sleeve, corset, sole shoe, shell, wrap, cover, with the purpose of curing or preventing a handicap, or any kind of prosthesis to replace a missing body part.

Thus, one aspect of the invention relates to a modelling device (1) for creating a 3- dimensional surface model of a body surface or body part which device comprises or is constituted of an elastic or plastic material configured for tight fitting to a body surface or a body part, which modelling device comprises a plurality of position sensors (2) distributed along a surface of the modelling device where each position sensor or a part of a position sensor can measure and define its position relative to one or more neighboring position sensors or parts of position sensors and further each position sensor or a group of position sensor comprises a transmitter configured to transmit position data to a receiver (3) during use.

That the material is configured for tight fitting to a body surface means that the material is configured to be in physical or touching contact with the body to be modelled during a modelling procedure. However, a model of a specific body part may be adjusted e.g. to release or increase pressure at one or more points.

According to an embodiment, the invention relates to a modelling device (1) for creating a 3- dimensional surface model of a body surface or body part which device comprises or is constituted of an elastic and/or plastic material configured for fitting to a body surface or a body part, the modelling device comprises a plurality of position sensors (2) distributed along a surface of the modelling device where each position sensor or a part of a position sensor can measure and define its position relative to one or more neighboring position sensors or parts of position sensors and further each position sensor or a group of position sensor comprises a transmitter configured to transmit position data to a receiver (3) during use, wherein at least one position sensor has both an active and a passive state.

In the passive state, the position sensor(s) receive(s) a first signal, which first signal may be lack of a signal i.e. no signal, indicating that the position sensor which brings the position sensor into this state. The first signal may have the form of an electric pulse of a first value. The first signal to all position sensors in the passive state may be identical.

In the active state, the position sensor(s) receive(s) a second signal, which second signal may be varied between a lower and an upper value either in steps or continues. The signal may have the form of an electric pulse of a second value, or a series of electric pulses of defined values. The second signal to all position sensors in the active state may be identical, or the second signal may be varied for each or a group of position sensors.

According to an embodiment, the position sensor (2) in the passive state may conform to the shape of the underlying surface providing position data reflecting the position of the position sensor relative to at least one other position sensor.

According to an embodiment, the position sensor (2) in the active state expands/extends in one or more dimension and/or moves and/or changes dimension in response to an electric pulse generating response data used to determine the solidity or elasticity or possible dimensional or size variation of tissue at the position of the position sensor (2).

According to an embodiment, the elastic or plastic material is configured to provide an outer support (orthosis) such as sleeve, corset, sole shoe, shell, wrap or cover, with the purpose of curing or preventing a handicap. If the elastic or plastic material is to fit closely to a flat surface, or at least a surface where the elastic / plastic material does not extend around a body part, the material may be plastic in at least one dimension and optionally elastic in a second dimension, or the position sensors may be constituted of an elastic or plastic material embedded in a plastic material.

According to an embodiment, the elastic or plastic material may be shaped as a sock or stocking adapted to fit a protruding body part such as a post-amputation stump, or the elastic or plastic material may be shaped as a cover, wrap, or sleeve embracing a body surface or body part. If the elastic or plastic material is to fit closely to a protruding body part or surface, where the elastic / plastic material may extend around the protruding body part, the material may be elastic in at least one dimension and optionally plastic in a second dimension, or the position sensors may be constituted of an elastic or plastic material embedded in a plastic or elastic material. According to an embodiment, at least one position sensor (2) or a group of position sensors (2) or all position sensors (2) may comprise or may be constituted of a Dielectric Elastomer capable of measuring a distance between two measuring points (m).

According to an embodiment, the position sensor may move or increase in size or decrease in size in at least one dimension upon receiving an electric impulse. Upon receipt of the electric impulse, the position sensor may generate response data used to determine a possible variation in size, or the solidity or hardness or elasticity of the tissue at the position of the position sensor (2). When the position sensor moves or changes size in a dimension, a part of the position sensor may be deformed or extended in a direction perpendicular to the body surface. The response data may then comprise data relating to size of deformation in the perpendicular direction and resistance to deformation.

According to an embodiment, either the receiver (3) or a connected computing unit (5) upon receipt of the position data is configured to determine the relative position of each position sensor (2) compared to one or more neighbouring position sensors creating a 3- dimensional model of a body surface or body part, which model may be either a negative model or a positive model.

According to an embodiment, the modelling device (1) and the position sensors (2) may be made of a material allowing re-use.

According to an embodiment, at least one or a plurality of or each measuring point (m) may be connected to at least two position sensors (2).

A second aspect of the present invention relates to a method for preparing a model using a modelling device (1) according to any embodiments of the first aspect, wherein

- the modelling device is adapted to and/or attached to a body surface or a body part and connected to a source of electricity,

- the modelling device is connected to a receiver (3),

- data is transmitted from the position sensors (2) of the modelling device to the receiver (3),

- the receiver either processes the received data or transfer the received data to a computing unit (5).

The receiver is normally local i.e. positioned together with the modelling device near the person, whereas the processing unit processing the received data may be positioned at distance to the person.

According to an embodiment of the second aspect, the computing unit (5) may be configured to determine a physical structure corresponding to the surface of the body surface or body part.

A third aspect of the present invention relates to a model prepared by use of a modelling device according to any of the first or second aspect, which model may e.g. be prepared by 3D printing.

A model according to the third aspect may be prepared from at least two different kinds of material or it may comprise at least two different kind of material structures e.g. a dense and a less dense structure. Such a construction may comprise volumes or areas with a softer or harder material adapted to the structure of the tissue in contact with the model during use. A different kind of material structure i.e. a less dense structure, may comprise cavities in order to provide a softer structure.

Brief description of the figures Figure 1A illustrates a simplified embodiment of a modelling device according to the invention for measuring dimensions of an amputee stump.

Figure IB illustrates a simplified embodiment of a modelling device according to the invention for measuring dimensions of a body surface or part of a body part.

Figure 2 illustrates use of a device according to the invention at different positions on a human body.

Figure 3 illustrates a second embodiment of a modelling device comprising common measurements points m for neighboring position sensors.

The present invention will now be described in more detail in the following.

Detailed description of the invention

Definitions

Prior to discussing the present invention in further details, the following terms and conventions will first be defined: In general - this expression is used if the feature following the words may be combined with all embodiments of the invention.

An orthosis - a device supporting, stimulating or measuring a body surface or body part such as sleeve, corset, sock, shell, wrap, cover.

A prosthesis - an artificial device to replace or augment a missing or impaired part of the body.

It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention.

The invention relates to a modelling device used when creating a 3-dimensional surface model of a body surface or body part.

The modelling device comprises or is constituted of an elastic or plastic material configured for tight fitting to a body surface or a body part. An elastic material is able to adapt to a shape and afterwards return to its relaxed shape after having been stretched or compressed, an elastic material is also referred to as being flexible. A plastic material is able to adapt to a shape, but a plastic material does not return to its original shape after having been stretched or compressed, a plastic material maintains a given shape, however, a plastic material is also referred to as being flexible. The elastic or plastic material may be configured for tight fitting to a body surface or a body part according to the users need, where tight fitting means that the elastic/plastic material is in physical and/or touching contact with the body part/body surface. The user may prefer a close fitting or a looser fitting, and optionally the elastic/plastic material may be provided with openings where a resulting model exercises no pressure, or the elastic/plastic material may be provided with protruding parts/areas where a resulting model exercise increased pressure.

The modelling device according to the invention comprises a plurality of position sensors which position sensors are either distributed/embedded in a flexible material or alternatively positioned at an inner surface of the modelling device where the inner surface of the modelling device is the surface of the modelling device being in contact with a person's skin during use. Also, the position sensors themselves may comprise the flexible material constituting the modelling device, i.e. the flexible material is a functional part of the position sensor.

Each position sensor or a part of a position sensor or a point of a position sensor may measure and define its position relative to one or more neighboring position sensors or parts of or points of position sensors and transmit the position data to a receiver.

In general, a position sensor may comprise e.g. a band or thread of material, i.e. one sensor comprises at least two measuring points/positions. In case the position sensor comprises a band or a thread of material, the position sensor is able to measure an increase or a reduction in a distance d between two opposite ends i.e. peripheric points, of the position sensor.

In case the position sensor comprises an area of a material, the position sensor is able to measure an increase or a reduction in the distance d between two opposite peripheric points of the position sensor area whether the area of the position sensor is circular or oval or polygonal such as rectangular.

The elastic or plastic material constituting a substantial part of the modelling device may comprise a polymer elastomer such as silicone or rubber wherein position sensors are either embedded in the polymer elastomer material or applied to the inner surface of the polymer elastomer material. However, the elastic or plastic material may also be constituted of a network of elastic position sensors e.g. provided with or attached to a protective cover or support constituted of a flexible material, which may also be elastic or plastic.

The position sensor may be a dielectric elastomer (DE) sensor where a laterally stretching of the sensor material will cause a change in capacitance, which change in capacitance may be correlated to the strain due to stretching, i.e. a distance. In general, the position sensor may be a sensor where a strain caused by a deformation will cause transmission an electrical signal, i.e. response data, correlated to the size of the deformation.

The sensor may be an elastic dielectric sheet with deformable electrodes which can be stretched twice its original length. The sensor comprises an insulating elastomer, covered by a compliant electrode connected to measure the capacitance of the electrode. When deformed it creates a capacitance change, and the capacitance is measured and converted to strain, displacement, pressure etc.

Sensors are embedded in the sock and their position on the part of the body can define distance from for example end point of sock to each sensor in longitudinal direction. In general, the modelling device may be shaped as a cover or a wrap to embrace a body surface or body part to be measured. Such a modelling device may be made in different standard sizes which will allow a user to choose a modelling device that may fit closely to the body surface or body part allowing the elasticity or plasticity of the device to provide a tight fit and a correct measurement of the complete body surface or body part.

That a modelling device fits closely around a body surface or body part means that an inner elastic or plastic surface is in touching contact with the outer surface of the body surface or body part. If the modelling device is made of a plastic material, the plastic material may be biased from its relaxed state i.e. the plastic material is extended beyond its relaxed state and brought into close, touching contact with the surface of the body surface or body part.

If the modelling device is a cover or wrap fitting around a body part, it may comprise a series of between 5-500 position sensors placed around the body part i.e. along the perimeter of the body part as illustrated in fig. 1A, alternatively 10-300 position sensors, or 50-300 position sensors. The position sensors along the perimeter of the body part may be supplied with a number of longitudinally positioned position sensors, which are positioned perpendicularly relative to the perimeter position sensors, or at least at an angle between 45-90° relative to the perimeter position sensors. The number of longitudinally positioned position sensors may be between 1-50, e.g. between 1-20, or e.g. between 3-20.

If the modelling device is not shaped to fit around a body part in such a way that the form may keep the modelling device in a desired position during measurement, the contact surface of the modelling device may comprise at least one or more adhesive point(s) configured to attach the modelling device to a steady or stationary position of the body surface or body part during measurement. E.g. the flexible material constituting part of the modelling device may provide an adherence to the person's skin. Alternatively, the modelling device may comprise a pressure device applying a light pressure on the cover or wrap to create a close touching contact between the body surface to be modelled and the modelling device.

The position sensors according to the invention may have both an active and passive state. In the passive state, the position sensors conform to the shape of the underlying surface and provide position data reflecting their relative position to one another. In the active state, the position sensors may move or expand in a direction perpendicular to the body surface in response to an electric pulse, i.e. the position sensor provide an orthogonal compression of the body surface. That the position sensor moves, means that a first part of the position sensor moves in a direction perpendicular to the body surface whereas a second part of the position sensor does not, e.g. the position sensor body is pivoted around an axis in such a way that one end of the position sensor pushes against the body surface. The response may be used to identify tissue density of the body surface.

All response data from the position sensors are transmitted to a receiver, this receiver may have the form of a physical box where electric signals constituting the response data from all position sensors are received. The receiver may comprise storing facilities to store the data received from the position sensors and the receiver may comprise a processor comprising software able to perform calculations based on the received data. However, the receiver will normally comprise a transmitter able to transmit the received data to a processing unit such as a computer. Software of a processing unit, whether this is the receiver or a separate computer, may calculate a model providing a geometric model of the skin surface of the body surface, and possibly a density model of at least parts of the body surface.

Based on the measurement a negative model or a positive model may be created e.g. by 3D printing or any other suitable method.

In order to provide an acceptable model of a body surface or body part, the number of position sensors or measuring points may be adapted to the complexity of the body surface where the complexity will depend on the curving of the body surface. E.g. the upper part of a stump of an amputated leg or a simple, rather straight body surface may be considered to have a "low complexity" as this surface is constituted of rather large and rather straight surfaces whereas the lower end or the support surface of an amputated leg or a complex body part such a foot or a hand may be considered to have a "high complexity" as this part is very curved and may have dents and highs which need to be incorporated into the model to give the person a high degree of comfort. According to the complexity of the body surface which the modelling device need to adapt to, a minimum distance between neighbouring measuring points may be defined.

E.g. for a significantly curved surface such as the end-area of an amputee stump or another complex body part, the maximum distance between two neighbouring position sensors or measuring points m provided by position sensors may be 5 mm, 4 mm, 3 mm,

2 mm, 1 mm, or 0.5 mm.

For a relatively straight surface such as e.g. an upper part of an amputee stump or a larger body surface, the maximum distance between two neighboring measuring points provided by position sensors may be 100 mm, 50 mm, 15 mm, 10 mm, or 5 mm.

According to a preferred embodiment, one measuring point may be common for two or more position sensors, e.g. the measuring point may constitute an intersection or junction, from where several position sensors are connected or extended.

In such a case, the position sensors constitute a physical network to make sure that all parts of a surface is measured and mapped by the modelling device. Optionally, the position sensors are serially connected in order to reduce the number of connections to a physical receiver such as a box.

Figure 1A illustrates a first embodiment of a modelling device 1 which may be used during measuring of an amputee stump of a leg.

Fig. 1A shows a modelling device 1 comprising a plurality of position sensors (2) placed in linear groups of varying length. In general, signals in form of response data from each sensor (2) are transferred to one or more receivers (3) either via physical lines (4) or via wireless connections. The embodiment shown in fig. 1A comprises 5 groups of serially connected sensors (2), and each group of position sensors (2) is connected to one receiver (3) via a physical line (4). When each receiver (3) has received the response data signals from a group of sensors (2), the response data are transferred to a computing unit (5) which computing unit comprises software for generation of a model based on the response data. The model may be transferred to a 3D-printer which may e.g. generate a negative model of a prosthesis or an orthosis. Fig. IB illustrates a second embodiment of a modelling device 1 according to the invention, which embodiment also comprises a plurality of position sensors (2) placed in linear groups of same length forming an almost square cover. In general, signals in form of response data from each sensor (2) are transferred to one or more receivers (3) either via physical lines (4) or via wireless connections. The embodiment shown in fig. IB also comprises 5 groups of serially connected sensors (2), where each group of position sensors (2) is connected to one receiver (3) via a physical line (4). When each receiver (3) has received the response data signals from a group of sensors (2), the response data are transferred to a computing unit (5) which computing unit comprises software for generation of a model based on the response data. The model may be transferred to a 3D-printer which may e.g. generate a negative model of a prosthesis or an orthosis.

Fig. 2 illustrates how the position sensors (2) may be placed either as a cover or wrap model on a body surface (to the right), or as a sock-like embodiment providing an interface between a body surface and a prosthesis (to the left).

Figure 3 illustrates how a third embodiment for use during measuring of an amputee stump of a leg.

Also, the embodiment fig. 3 illustrates h how a measure point m may be shared and in contact with a plurality of position sensors as neighboring position sensors have common contact points. Fig. 3 illustrates possible positions of two neighboring measure points m.

The modelling device and the position sensors may be constituted of a material(s) allowing re-use of the device. If the modelling device is to be re-used, the materials constituting the device should e.g. allow for several extensions and adaptions to a body surface and also the materials constituting the device should allow for cleaning, e.g. the modelling device including the position sensors may be washable or the materials constituting the modelling device may at least allow wiping with a disinfectant such as an alcohol.