WorldWide Drilling Resource

How to Weigh and Warm a Cat by Britt Storkson Owner, P2FlowLLC Ve n d o r s a r e constantly coming out with new materials and applications for existing materials, and it’s a good thing. The newest prod- ucts I have seen are three types of fab- rics which have electrical properties. Often, certain products are impossible or impractical (mostly because of cost con- siderations) to produce until better or lower cost materials come on the market. These fabrics could make something which isn’t now practical or profitable to produce something worth making and marketing. The first one is a stretchy fabric which changes resistance depending on how much you stretch it. There are all sorts of uses for this fabric in wearables. It could be sewn into the elbow area of a coat or shirt and be used to monitor the arm position of this particular garment. It could be attached to a cabinet door and, with a little circuitry, allow a light to turn on inside the cabinet when the door is opened, and off when the door is shut. The second one is a pressure-sensor fabric. When this fabric is compressed, the resistance changes when weight is ap- plied to it. This would be great for measuring fluid levels in closed containers . . . like coffee in an airpot. An airpot is the thermos type container with an air pump on top you press down when you want the coffee or whatever is stored in the pot. This pressure sensor does not need to be a highly accurate device. We just need to know if the airpot was full or empty, not the exact weight. Several years ago, I made a device that would “weigh” the airpot and detect how full the airpot was. It didn’t work well be- cause I didn’t want to spend the money for a good weight/pressure sensor. I could have used strain gauges, but they cost about $70 per gauge for the type I needed, and at least three of them would be required for each airpot. Plus, I had three airpots to make these for. This pressure-sensing fabric would have been the ideal and relatively inexpensive solution. The third one is a fabric which produces heat when an electric current is applied. First, you measure the resistance of the fabric and then apply a voltage to the fabric to get the desired heat output. If the resistance is 100 ohms and we want to apply 12 volts using Ohm’s law 12/100 = 0.120 amps or 120 mA. 12 volts x 0.120 = 1.44 watts. To get more heat output with the same resistance, we would increase the voltage. To get less heat we would reduce the voltage. It’s always a good practice to have a temperature “feedback” . . . a sensor able to control the heat output by turning the heater off and on. While I was contemplating the uses for these fabrics, my thoughts turned to a cat. My wife has a cat which is very smart albeit very spoiled. If you give him some food he doesn’t like, he will either sit in front of his food dish and stare at the food or turn his back on the food dish. If this cat is hungry and you go to the bathroom, he will sit outside the door and wait for you to come out. Once you come out he will walk ahead of you until he gets to his food dish, at which time he will turn himself sideways so you either have to step over or around him to get where you want to go. Since our cat is elderly, we would like to make a comfortable bed for him. First, we need to have a Storkson cont’d on page 36. 20 JULY 2017 WorldWide Drilling Resource ®