Technical Field

The invention belongs to the field of devices for use in medical sciences and diagnostics.

The International Patent Classification (IPC) designation is: A62B9/003, A62B18/025, A42B 1/008, A41D 13/11, A41D 13/005.

Background Art

In recent years, we have witnessed the pandemic of the COVID-19 virus, which has forced the mass and daily use of protective face masks that all citizens are obliged to wear, in addition, the use of face masks is quite widespread in cold regions, among athletes who engage in winter sports. In this regard, the use of a mask has the task of protecting the user or athlete from the effects of very cold air in very cold weather conditions.

In addition to the use of a mask to protect against virus transmission, in these cases it can have another very important role in protecting the user from extreme cold and providing comfort and pleasure in staying or working outdoors despite low temperatures. Within the framework of this invention, it is proposed to enrich the mask with heaters, so that the mask could also be used as a means of protecting the face when the user is in a very cold environment. This invention proposes a new design, fabrication and characterization of a face mask heater in which the electrodes are embroidered with conductive silver thread. In addition, electronics were developed to control the operation of the heater on the face mask.

The invention relates to the production of a textile heater, embroidered on a face mask, where conductive silver thread is used for the production of the structure of the heater. In addition, an electronic circuit that controls the operation of the heater was developed and tested.

The use of inductors as heaters has a very wide range of applications, starting from the auto industry, the aviation industry, and they are increasingly used in medicine, sports medicine for heating, i.e. raising the temperature in certain situations. In addition, the corona virus pandemic has forced the use of face masks indoors, and in some countries also outdoors.

That mass use of masks leads to the idea of installing certain sensors or, in our case, textile embroidered heaters that could be used for other purposes, specifically for heating and protecting the user from extremely low temperatures when outside or in the case of workers who work in cold stores, so because of the nature of the work must constantly change the environment and temperature in which they stay. Also, people suffering from lung diseases have a big problem in winter when they have to go outside from a warm place, so the difference in air temperature is drastic and over 20 °C, so the mask with the proposed resistance heater would allow them to comfortably move from one environment to another without great stress and pain.

The following scientific papers present some of the presented solutions for making face masks with sensors.

Scientific Paper: (1) UCLA mechanical engineers have developed a prototype face mask that uses heat to destroy viruses and other microscopic pathogens (https://www.mae.ucla.edu/mechanical-engineers-develop-heate d-face-masks- to-kill-viruses-and-curb-disease-spread/).

Disposable masks are used to provide a physical barrier that offers protection to people who may be exposed to airborne viruses and bacteria. The UCLA design is modeled after N95 and KN95 face masks and features heatable metal wires between the outer and inner layers of the mask. The wires, which do not touch the face, are heated to a temperature of about 40 degrees Celsius (about 104 degrees Fahrenheit) - enough to kill any remaining viruses that pass through the outer layer of the filter.

Scientific paper: P. Pattanaik, W. Holderbaum, A. Kandual and H. P. Tripathy, "UVC LED and Conducting Yam-Based Heater for a Smart Germicidal Face Mask to Protect against Airborne Viruses", Materials MDPI, 2021, 14 ( 22), https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8620325/ - One of the most accepted prevention measures that can limit the spread of airborne viruses in the form of respiratory viral diseases, including the new strain of COVID -19, is wearing a suitable mask. If the surface of the mask is heated to 65 to 70 °C, this can potentially help reduce the build-up of viruses or bacteria. The above paper proposed an intelligent mask that serves FAR-UV-C and has a yam-based heater that could potentially be activated in a controlled manner to kill the vims.

The following patents/patent applications represent some of the proprietary, known heated face mask enrichment solutions for various applications.

Patents US 11096438B1 titled published on Aug. 24, 2021 and titled “All weather electric indoor/outdoor heat exchanger face mask” describes a face mask formed with a breathing chamber that provides adjustable warm and humid air for inhalation. The breathing chamber heats cold air that is breathed in through a face mask during normal breathing, which is worn over the person's nose and mouth. The temperature gauge monitors the temperature for future adjustment of the amount of heat-generating current. The air in the chamber is heated for inhalation using a carbon fiber resistance band. The temperature of the resistive material (and thus the hot air generated) is regulated/adjusted by increasing or decreasing the current output settings on the power supply. Warm and moist air is produced. The face mask can be part of a hood or hat, or other headgear, or stand alone with straps around the head, optionally with an adjustable solar battery.

Patent application US4793343A published on August 20, 1987 entitled “Respiratory heated face mask” describes a face mask for use in cold weather to supply warm air for normal breathing to persons with respiratory and cardiac diseases to avoid discomfort, pain and limited mobility caused by breathing cold air and healthy people engaged in strenuous activities in cold weather. The face mask has inlet and outlet check valves and a cold air intake chamber with an electric heating element inside that heats the cold air to supply warm air for inhalation. Preferably, the heating element is powered by a portable battery and controlled by electronic circuitry to maintain the heated air within a predetermined temperature range.

Patent application US4620537A published April 4, 1986 entitled “Cold weather face mask” describes a breathing mask having an intake air heater and a heat and moisture exchange medium located below the nose and positioned for minimal exposure to heat transfer to the exterior. Their mounting is somewhat cantilevered from the mask, in order to minimize the direct transfer of heat to the outside. Electric heating elements are provided and powered from a power pack mounted in the hood itself at a relatively low level. Part of the inhaled air passes through the first filter and moisture collection medium to the mouth and/or nose of the person wearing the mask. All inhaled air passes through a heat exchanger and a second filter and moisture exchanger. A valve is provided so that all air exhaled during normal breathing passes through both moisture exchangers. A second valve is provided in the mask wall to allow the exhalation of any air that may pass through both exchangers during strenuous exercise and unusually high breathing rates.

Patent USRE36165E issued on December 29, 1995 entitled “Heating and humidifying respiratory mask” describes a lightweight face mask capable of heating and humidifying inhaled air with pre-exhaled air by passing air through a highly efficient heat exchanger located within the mask. The heat exchanger has many layers of metal mesh through which the air generally passes in a linear fashion. The warm exhaled air heats the mesh which in turn heats the incoming air before it is inhaled. Moisture from the exhaled air condenses on the relatively cool heat exchanger and moistens the incoming air. Inhaled air enters the mask mostly upwards, and exhaled air comes out mainly downwards.

Disclosure of the Invention

Our invention is based on the fabrication of an inductive heater using the embroidery technique, using thread with conductive silver fibers on a professional embroidery machine. Standard protective face masks, for one-time use, which are easily available and quite cheap, were used for the base or substrate on which the sensor is manufactured. The design of the heater was done in a professional design program, after which the structure was transferred to the embroidery machine where the functional structure of the heater was obtained by using conductive silver thread.

The embroidery technique represents a cheap technique in the new field of textile electronics. This technique is actually a standard embroidery technique using a sophisticated computer-controlled embroidery machine. In addition, in order to create a conductive structure using the knitting technique, it is necessary to use a thread that has conductive threads in it, in our case, thread with silver threads was used.

Our proposed invention demonstrates for the first time the fabrication of a mechanically flexible induction heater on a standard disposable face mask. The whole technique of making an embroidered inductive heater on a face mask involves making the inductor in a short period of time (less than 10 minutes) and in conditions that do not require a clean room and the use of expensive manufacturing techniques.

Brief Description of the Drawings

Figure 1 shows the concept of the invention

Figure 2 shows the concept of invention when a man wears the mask of invention

Figure 3 shows the mask testing of the invention

Best Mode for Carrying Out of the Invention

Based on the above, the basic innovative steps of the invention are:

1. Determination of the temperature range of the heater

2. Conductive structure design of the heater suitable to fit on the protective face mask

3. Fabrication of heaters using a modem embroidery machine and conductive thread with silver threads

4. Characterization and testing of electrical properties of the heater

5. Development of an electronic assembly that enables control of the operation of the heater on the mask.

By connecting this heater on the mask with specially developed electronics, the user can comfortably use and control the operation of the heater. The big advantage of the proposed mask with a heater is the relatively cheap cost of manufacturing and replacing it with another mask, while we can use the same electronic circuit, which allows for a much lower final price of the proposed device. The degree of innovation of the invention is reflected in the realization of a completely new textile, which means also mechanically flexible, heater using the knitting technique, where the structure of the heater is actually realized by using threads with conductive silver threads. After connecting to the electronics, the temperature can be regulated on this heater.

Figure 1 shows a resistance heater embroidered on a standard face mask using an embroidery machine. A standard disposable face mask 100 was used for the base, i.e. the substrate on which the sensor was made, while the heater is a structure in the form of an inductor 101, which was made using the embroidery technique on a soft embroidery machine, using a special thread with silver threads. This resistance heater is embroidered on the outside of the protective mask and its dimensions are determined by the dimensions of one strip of this protective mask (in the outstretched state), to be at the height of the nose of the person wearing the mask with the heater. This embroidered layer does not disturb the normal and usual stretching of the mask over the whole face when in use. Also, in specific application, it does not significantly increase the price of the mask, because the thread used is a cheap and ubiquitous material. After the heater is made on the embroidery machine, the clips for connecting to the electronics 102 are installed, which enables the control of the inductive heater for comfortable use of the mask in all situations. In addition, it should be noted that the shape and size of the heater can be different; it is even possible for the heater itself to be shaped to represent a fashion detail, so that when it is not in use it looks very nice. Also shown is the appearance of the mask on the face of the user 104 and the position of the inductive heater when using the mask with an embroidered heater. During the passage of current through the structure of the heater, the temperature of the conductive silver structure increases, this also leads to the local development of heat. In the testing phase, a thermal imaging (infrared camera) was used to monitor the locally developed temperature.

The size and shape of the heater can be changed according to the desired values that we want to achieve, with the fact that the size of the face mask must be taken into account, which is the limiting factor here. By changing or increasing the surface or the length of the conductive segments as well as the width, we directly affect the increase in the structure of the heater.

Figure 2 shows the change of the heater on the user's face mask, the electronics for temperature control as well as the IR camera used to check the temperature value on the heater.

After the component was realized with the embroidery machine, it was tested, by measuring the inductance and resistance as a function of frequency using (in Figure 3) the device HI OKI Chemical Impedance Analyzer IM 3590 and the IR camera to control the temperature of the heater. Industrial Applicability

This invention involves the realization of a conductive textile heater structure on a protective face mask that is widely used, and as such this invention can find wide application primarily in medicine, sports medicine as well as for free use by people staying in extremely cold conditions as well as by humans who have lung diseases or sinus infections.

In addition to being used for medical purposes, this invention could also be used by athletes who engage in winter sports (skiers, skaters), as well as by people who work, for example, in refrigerators, and during the day they change their environment several times from extremely cold to extremely hot. warm. The proposed design of the heater can be applied to other parts of our clothing that we wear, for example, in hats, scarves, headphones, etc.