1. A gas sensor for detecting a target gas, the gas sensor comprising:
a gas-permeable base; and
a detector provided on the base,
wherein the detector changes color in response to a pH variation generated when reacting with the target gas having permeated the base.
2. The gas sensor according to claim 1, wherein the detector includes a hydrophilic membrane having a detection solution.
3. The gas sensor according to claim 2, wherein the detection solution includes at least one pH indicator that changes color in response to pH variation generated when the detection solution reacts with the target gas.
4. The gas sensor according to claim 2, wherein:
if acetic acid is contained in the target gas, the detection solution includes at least one of a bromothymol blue pH indicator from 0.001 weight percent to 0.1 weight percent and a chlorophenol red pH indicator from 0.001 weight percent to 0.1 weight percent.
5. The gas sensor according to claim 2, wherein the detection solution includes a buffer solution having a dissociation constant (pKa) of 3 to 10.
6. The gas sensor according to claim 5, wherein the buffer solution includes at least one of sodium acetate, sodium carbonate, sodium bicarbonate, and sodium citrate.
7. The gas sensor according to claim 6, wherein the sodium acetate buffer solution includes acetate ions of 0.1 mM to 1000 mM.
8. The gas sensor according to claim 5, wherein the detection solution includes a buffer solution in which conjugate ions having the same dissociation constant as in the target gas are dissolved.
9. The gas sensor according to claim 8, wherein a resolution of the gas sensor is changed according to the density of conjugate ions dissolved in the buffer solution.
10. The gas sensor according to claim 5, wherein:
if the target gas is volatile organic acid, the detection solution includes a buffer solution having an initial pH value higher than a dissociation constant of target gas.
11. The gas sensor according to claim 10, wherein a sensing range of the target gas is changed according to the initial pH value of the buffer solution.
12. The gas sensor according to claim 2, wherein the detection solution includes at least one of glycerin, ethylene glycol, polyethylene glycol, and calcium chloride.
13. The gas sensor according to claim 2, wherein the detection solution is absorbed in the hydrophilic membrane and fixed thereto.
14. The gas sensor according to claim 2, wherein the hydrophilic membrane includes at least one of cellulose ester, glass fiber, cellulose acetate, cellulose fiber, litmus paper, Korean traditional paper, and filter paper.
15. The gas sensor according to claim 1, wherein the base includes a hydrophobic membrane.
16. The gas sensor according to claim 1, wherein the base includes at least one of polytetrafluoroethylene, thermoplastic polyurethane, polyethylene, low density polyethylene, linear low density polyethylene, high density polyethylene, and Tyvek.
17. The gas sensor according to claim 1, further comprising:
a transparent membrane attached to the detector, and configured to prevent gas permeation.
18. The gas sensor according to claim 1, wherein the target gas includes gas generated from a ripening process of food.
19. The gas sensor according to claim 1, further comprising:
an image detector configured to obtain an image of the detector; and
a transmitter configured to output data regarding an image detected from the image detector.
20. The gas sensor according to claim 19, further comprising:
a battery configured to provide a power source to the image detector and the transmitter.
21. The gas sensor according to claim 19, further comprising:
a wireless power receiver configured to provide a power source to the image detector and the transmitter.
22. A refrigerator comprising:
a gas sensor including a gas-permeable base and a detector provided on the base, wherein the detector changes color in response to a pH variation generated when reacting with a target gas having permeated the base; and
an image sensor configured to obtain an image of the gas sensor.
23. The refrigerator according to claim 22, further comprising:
a controller configured to determine a state of a target food and a storage position of the target food on the basis of the gas sensor image obtained from the image sensor.
24. The refrigerator according to claim 23, wherein the controller is configured to pre-store data regarding the color of the gas sensor and the target food state based on the color.
25. The refrigerator according to claim 24, wherein the controller determines a color difference between a first color obtained before exposure to the target gas and a second color obtained after exposure to the target gas using the image obtained from the image sensor, and determines a state of the target food on the basis of the determined color difference using the pre-stored data.
26. The refrigerator according to claim 22, further comprising:
a display configured to display at least one of the target food state determined on the basis of the gas sensor image obtained from the image sensor and information regarding a storage position of the target food.
27. A method for manufacturing a gas sensor, comprising:
fixing a detection solution to a hydrophilic membrane; and
attaching the hydrophilic membrane to a hydrophobic gas-permeable membrane.
28. The method according to claim 27, wherein the fixing of the detection solution to the hydrophilic membrane includes:
absorbing the detection solution, which includes a pH indictor, a buffer solution, and a moisture absorbent, into the hydrophilic membrane; and
heating the hydrophilic membrane in which the detection solution is absorbed at a predetermined temperature for a predetermined time.
29. The method according to claim 27, further comprising:
heat-bonding a transparent gas-impermeable membrane to the hydrophilic membrane attached to the hydrophobic membrane.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A medical device, at least a portion of which is insertable or implantable into the body of a patient, said medical device comprising:
a tubular body formed from a plurality of structural elements, the plurality of structural elements forming windows such that the tubular body does not have a continuous outer shell;
a polymeric layer disposed about said tubular body, said polymeric layer comprising a biodisintegrable polymer and a plasticizer;
a high-molecular-weight therapeutic agent disposed below or within said polymeric layer; and
wherein the plasticizer is configured to facilitate the transfer of the high-molecular weight therapeutic agent through the polymeric layer; wherein the plasticizer is configured to facilitate the transfer of the high molecular weight therapeutic agent through the polymeric layer by altering the porosity of the polymeric layer.
2. The medical device of claim 1, wherein said biodisintegrable polymeric layer comprises one or more of lactic acid polymers and copolymers, glycolic acid polymers and copolymers, trimethylene carbonate polymers and copolymers, caprolactone polymers and copolymers, hyaluronic acid polymers and copolymers, hydroxybutyrate polymers and copolymers, and tyrosine-based polymers and copolymers.
3. The medical device of claim 1, wherein said biodisintegrable polymeric layer comprises one or more of (a) hyaluronic acid polymers, (b) copolymers of lactic acid and glycolic acid, and (c) a tyrosine-derived polycarbonate.
4. The medical device of claim 1, wherein said medical device is selected from a catheter, a balloon, a filter, a coil, a clip and a sling.
5. The medical device of claim 1, wherein said medical device is an intraluminal stent.
6. The medical device of claim 5, wherein said intraluminal stent is a vascular stent.
7. The medical device of claim 1, wherein said high-molecular-weight therapeutic agent is plasmid DNA.
8. The medical device of claim 1, wherein said plasticizer is selected from one or more of glycerol, triacetyl glycerin, ethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, polyalkylene oxides, citric acid esters, sebacic acid esters, phthalic acid esters, and silicone fluid.
9. The medical device of claim 1, wherein said plasticizer is selected from one or more of polyethylene glycol, silicone fluid, polyethylene oxide, and copolymers of polyethylene oxide and polypropylene oxide.
10. The medical device of claim 1, wherein the polymeric layer has a composition gradient in a direction normal to the surface of the polymeric layer.
11. The medical device of claim 10, wherein the composition gradient is a gradient in porosity.
12. The medical device of claim 10, wherein the composition gradient is a gradient in composition of the relative portions of two or more monomer species within a copolymer or a gradient in the relative portions of two or more polymers within a polymer blend.
13. A medical device, at least a portion of which is insertable or implantable into the body of a patient, said medical device comprising:
a tubular body formed from a plurality of structural elements, the plurality of structural elements forming windows such that the tubular body does not have a continuous outer shell, the tubular body comprising:
a polymeric layer comprising one or more lactic acid polymers, copolymers, or combination thereof and a plasticizer; and
a high-molecular-weight therapeutic agent disposed below or within said polymeric layer; and
wherein the plasticizer is configured to provide crack resistance to the polymeric layer and to facilitate the transfer of the high-molecular weight therapeutic agent through the polymeric layer; wherein the plasticizer is configured to facilitate the transfer of the high molecular weight therapeutic agent through the polymeric layer by altering the porosity of the polymeric layer.