Wearable sensing apparatus
A compact wearable sensing device with a cantilever beam and adjustable elastic pad monitors pressure and temperature in real time, addressing bulkiness issues and reducing bedsores risk and care costs.
Patent Information
- Authority / Receiving Office
- KR · KR
- Patent Type
- Applications
- Current Assignee / Owner
- 국립창원대학교산학협력단
- Filing Date
- 2025-01-10
- Publication Date
- 2026-07-21
AI Technical Summary
Conventional wearable sensing devices for preventing bedsores are bulky due to the need for long fixed-beam strain gauges, which compromises their wearability and increases medical costs.
A wearable sensing device with a cantilever beam strain gauge, an elastic pad made of dragon skin or PDMS, and a pressure pad, combined with a temperature sensor, to monitor pressure and temperature in real time, using a tri-layered film structure and adjustable elastic modulus for sensitivity control.
The device provides stable pressure and temperature monitoring, reducing the risk of bedsores while minimizing device size and caregiver burden, thus lowering medical costs and enhancing patient care quality.
Smart Images
Figure PAT00004_ABST
Abstract
Description
Technology Field
[0001] The present invention relates to a wearable sensing device, and more specifically, to a wearable sensing device developed in a form that can be worn (attached) to the human body to prevent bedsore-related diseases that frequently occur in patients who lie in bed for a long time or live in a wheelchair, and which can monitor the pressure and temperature of the area of wear in real time. Background Technology
[0002] As is well known, pressure ulcers refer to skin damage, or ulcers, caused by ischemia of the skin, subcutaneous fat, or muscles resulting from impaired blood circulation and a lack of oxygen and nutrient supply in body parts subjected to continuous pressure. These pressure ulcers typically occur on skin areas in direct contact with the floor when severely ill patients lie in bed for extended periods.
[0003] To prevent bedsores, it is very important to change the patient's position every 1 to 2 hours to prevent pressure from concentrating in one place for a long time. However, since caregivers perform periodic position changes while keeping track of the time in most cases, not only are caregiving costs considerable, but bedsores frequently occur when position changes are not performed in a timely manner, causing difficulties.
[0004] Accordingly, wearable sensing devices have been developed that can be attached to multiple areas at risk of developing bedsores, such as the patient's back, feet and legs, waist, or buttocks, to monitor pressure and temperature in those areas in real time. These devices are being utilized to notify caregivers of the time to change positions in a timely manner or to automatically change the patient's position using an automatic positioning bed.
[0005] Meanwhile, conventional wearable sensing devices for this purpose have adopted a thermistor with a negative temperature coefficient (NTC) as a temperature sensor and a fixed-beam strain gauge as a pressure sensor, in which both ends of the beam to which pressure is applied are fixed and the pressure applied to the center of the beam is measured.
[0006] However, in order to obtain the desired pressure sensitivity with conventional fixed-beam pressure sensors, a very long beam is required, which has problems such as increasing the size of the wearable sensing device. Prior art literature
[0007] : KR1020190129838A: KR1020210069140A: KR1020120050099A The problem to be solved
[0008] The main objective of the present invention is to provide a wearable sensing device that is developed in a form that can be worn (attached) to the human body to prevent bedsore-related diseases that frequently occur in patients who are bedridden for a long time or live in a wheelchair, and which can monitor the pressure and temperature of the area of wear in real time. means of solving the problem
[0009] A wearable sensing device according to the present invention for achieving the above objectives comprises: a strain gauge formed in the shape of a cantilever beam; a support member positioned below the strain gauge to support one end of the strain gauge; a temperature sensor for detecting temperature; an elastic pad positioned below the other end of the strain gauge and having an elastic modulus capable of controlling sensitivity to a pressure range related to bedsores; and a pressure pad installed above the elastic pad with the strain gauge in between to transmit external pressure to the strain gauge.
[0010] In the above configuration, the strain gauge is composed of a three-layer structure consisting of an attachment plate made of an insulating thin plate, a metal thin film deposited on the attachment plate, and a cover plate covering the metal thin film.
[0011] The elastic pad is made of dragon skin or PDMS (polydimethylsiloxane) material.
[0012] The elastic pad controls sensitivity to pressure ranges associated with bedsores by the elastic modulus, which is determined by varying the mixing ratio of the main material, dragon skin or PDMS, and the crosslinking agent, as well as the cross-sectional area and height of the elastic pad. Effects of the invention
[0013] According to the wearable sensing device of the present invention, from a scientific and technical perspective, it can be worn by patients who are bedridden or living in a wheelchair for a long time to monitor pressure and temperature applied to the human body in real time with stable and desired sensitivity, thereby contributing significantly to the prevention of bedsores, and from an economic and industrial perspective, it can reduce medical costs and promote the development of the medical device sector.
[0014] In addition, according to the wearable sensing device of the present invention, it can contribute to overall social welfare by improving the quality of life of patients in social aspects, alleviating the burden on caregivers, and reducing long-term treatment and complications caused by bedsores. Brief explanation of the drawing
[0015] FIGS. 1a and FIGS. 1b are a perspective view and a front view, respectively, of a wearable sensing device of the present invention. FIG. 2 is a perspective photograph of the wearable sensing device of the present invention. Figure 3 is a graph showing the stress-strain relationship in a typical linear elastic body. FIGS. 4a and FIGS. 4b are a perspective photograph and a front photograph, respectively, showing the behavior of a strain gauge when pressure is applied to the wearable sensing device of the present invention. Specific details for implementing the invention
[0016] Hereinafter, preferred embodiments of the wearable sensing device of the present invention will be described in detail with reference to the attached drawings. Detailed descriptions of known functions and configurations that may unnecessarily obscure the essence of the invention are omitted. Furthermore, since the embodiments of the present invention are provided to more completely explain the invention to a person with average knowledge in the art, the shapes and sizes of elements in the drawings may be exaggerated for clearer explanation.
[0017] FIGS. 1a and FIGS. 1b are a perspective view and a front view, respectively, of a wearable sensing device according to a preferred embodiment of the present invention, and FIG. 2 is a perspective photograph of the wearable sensing device of the present invention.
[0018] As illustrated in FIGS. 1 and 2, the wearable sensing device of the present invention comprises a strain gauge (10) formed in the shape of a cantilever beam, a support member positioned at the bottom of the strain gauge (10) to support one side of the strain gauge, an elastic pad (30) positioned at the bottom of the other end of the strain gauge (10) to elastically deform and restore depending on whether pressure is applied to the strain gauge (10), a pressure pad (40) installed on the upper part of the elastic pad (30) with the strain gauge (10) in between to transmit external pressure to the strain gauge (10), and a temperature sensor (20) to detect temperature, and can be manufactured in the form of a wearable device that can be attached to the human body.
[0019] In the above configuration, the strain gauge (10) is a type of resistance sensor that is made of resistance and is attached to the object to be measured to convert the physical strain of the object to be measured into an electrical signal in a Wheatstone Bridge manner to measure the amount of deformation of the object to be measured.
[0020] Such strain gauges (10) can be manufactured in a tri-layered film structure having a cantilever beam shape to prevent external damage while ensuring stable elastic recovery. Specifically, the strain gauge (10) of the present invention can be made of a tri-layered film structure consisting of a metal thin film, for example, a gold (Au) thin film with a thickness of 30 to 500 nm, which functions as a grid by being deposited on an insulating thin film, for example, a polyimide or epoxy, and a cover plate that covers the gold (Au) thin film to prevent damage to the gold (Au) thin film and reduce external noise.
[0021] Meanwhile, the strain gauge (10) can be manufactured to have a size that is comfortable to attach to the human body and satisfies the desired pressure sensitivity, for example, a horizontal length of 1 to 3 mm, preferably 1.4 mm (based on FIG. 1b; the same applies hereinafter), a width (vertical length) of 0.2 to 1 mm, preferably 0.6 mm, and a thickness of 0.03 to 0.1 mm, preferably 0.05 mm.
[0022] Meanwhile, the support supports one side of the strain gauge (10) from the bottom of the strain gauge (10), and can be positioned at a location that is recessed by a predetermined length, for example, 0.1 to 0.5 mm, preferably 0.23 mm, from one end of the strain gauge (10). In the wearable sensing device of the present invention, a temperature sensor (20) can be used as a support to improve space utilization efficiency.
[0023] This temperature sensor (20) can be implemented as a thermistor having a negative resistance coefficient and used to monitor the temperature of the skin contact area of the human body in real time. The size of the temperature sensor (20) is preferably 0.1 to 0.5 mm, with a width and thickness (height) of 0.3 mm, and the width (length) is preferably the same as the width of the strain gauge (10).
[0024] Next, the elastic pad (30) is placed at the lower end of the other end of the strain gauge (10) to prevent damage caused by excessive deformation of the strain gauge (10), and elastically deforms and restores depending on whether pressure is applied to the strain gauge (10). Specifically, this elastic pad (30) is Dragon Skin, a high-performance silicone rubber. TM It can be made by including synthetic resin materials such as ) or PDMS, and the desired pressure sensitivity can be varied depending on the mixing ratio with the crosslinking agent.
[0025] Here, polydimethylsiloxane (PDMS) is a type of silicone elastomer that behaves like a highly viscous liquid, similar to honey, at high temperatures, but like a solid with elasticity, similar to rubber, at low temperatures. By using PDMS as the main material and varying the mixing ratio of the added crosslinking agent, the physical properties (elasticity) can be altered. Specifically, a higher ratio of the crosslinking agent results in stronger crosslinking, increasing elasticity and decreasing viscosity; conversely, a lower ratio retains the mobility of the PDMS chains, leading to decreased elasticity and increased viscosity.
[0026] In this way, in the wearable sensing device of the present invention, the elastic modulus (E; Young's modulus) of the elastic pad (30) can be adjusted to a desired value, for example, 100 kPa to 1 MPa, by appropriately selecting the mixing ratio of the main material of the elastic pad (30), for example, PDMS, and the cross-linking agent, and the cross-sectional area and height of the elastic pad (30) can be appropriately selected accordingly, thereby controlling the sensitivity to the pressure range (~10 kPa) associated with bedsores. For example, when the mixing ratio of PDMS to cross-linking agent is 10:1 based on weight ratio, the elastic modulus becomes 1.527 MPa, but the elastic modulus can also be controlled by varying the process temperature.
[0027] The size of such elastic pad (30) is 0.1 to 0.5 mm, preferably 0.3 mm, and the width (height) is preferably the same as the width of the strain gauge (10).
[0028] Mathematical Equation 1 below is the relationship between the spring constant and the elastic modulus, and Figure 3 is a graph showing the stress-strain relationship in a general linear elastic body.
[0029]
[0030] In Equation 1, F represents the force applied to the elastic pad (30), E represents the elastic modulus of the elastic pad (30), A and L represent the cross-sectional area and height of the elastic pad (30), respectively, and δ represents the amount of deformation of the elastic pad (30). Here, the elastic modulus (E) is a proportionality constant that resists elastic deformation and has a unique value that varies depending on the material, and its unit is Pascal [Pa = N / m² 2 ]am.
[0031] Meanwhile, the pressure pad (40) can be made of a synthetic resin material, such as PDMS. The pressure pad (40) has a width and thickness (height) of 0.1 to 0.5 mm, preferably 0.3 mm, and its width (length) is preferably the same as the width of the strain gauge (10).
[0032] FIGS. 4a and FIGS. 4b are a perspective view and a front view, respectively, showing the behavior of a strain gauge when pressure is applied to the wearable sensing device of the present invention. As shown in FIG. 4, when pressure is applied to the other end of the strain gauge (10) through a pressure pad (40), the strain gauge (30) bends according to the applied pressure, and the elastic pad (30) is compressed within a pressure range related to bedsores. Consequently, by determining the change in resistance due to the deformation of the strain gauge (10), that is, the degree of compression of the elastic pad (30), the pressure applied to the skin of the human body can be accurately determined by the relationship between the resistance of the strain gauge, the elastic modulus (E) of the elastic pad (30), and the cross-sectional area and height of the elastic pad (30).
[0033] Meanwhile, the wearable sensing device of the present invention described above, when configured individually, can communicate with an NFC reader via Near Field Communication (NFC) to transmit pressure and temperature information monitored for the corresponding attachment site on the human body to the NFC reader in real time.
[0034] To this end, the wearable sensing device of the present invention may include an NFC SoC (System on Chip) and a coil antenna for harvesting its own operating power.
[0035] The present invention has been described with reference to an embodiment illustrated in the accompanying drawings, but this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Accordingly, the true scope of protection of the present invention should be determined only by the appended claims.
Claims
Claim 1 A wearable sensing device comprising: a strain gauge formed in the shape of a cantilever beam; a support disposed below the strain gauge to support one end of the strain gauge; a temperature sensor for detecting temperature; an elastic pad disposed below the other end of the strain gauge and having an elastic modulus capable of controlling sensitivity to a pressure range related to bedsores; and a pressure pad installed above the elastic pad with the strain gauge in between to transmit external pressure to the strain gauge. Claim 2 A wearable sensing device according to claim 1, wherein the strain gauge is characterized by a three-layer structure comprising an attachment plate made of an insulating thin plate, a metal thin film deposited on the attachment plate, and a cover plate covering the metal thin film. Claim 3 A wearable sensing device according to claim 2, characterized in that the elastic pad is made of dragon skin or PDMS (polydimethylsiloxane) material. Claim 4 A wearable sensing device according to claim 3, characterized in that the elastic pad controls sensitivity to pressure ranges associated with bedsores by means of the elastic modulus determined by varying the mixing ratio of the main material, dragon skin or PDMS, and the crosslinking agent, and the cross-sectional area and height of the elastic pad.