Excerpt from
Adventures of an Inventor by Jacob Fraden
About Instant Thermometer
The first prototype of Instant Thermometer was made of an old audio cassette. It went like this: before taking a measurement, I pulled out the sliding door on my thermometer (I called that door a shutter), opened my mouth, placed the square window of the thermometer on the surface of my tongue, and released the shutter. The rubber band pulled it back, the door closed quickly, the polymer film generated an electric spike which was measured by the electronic circuit, and the voltmeter showed the numbers graduated in degrees Celsius.
The thermometer worked very fast, within a fraction of a second. Thinking about a name for this new product, I decided to call it The Instant Thermometer, a name which stuck and is used to this day… To my joy and pride, the prototype worked pretty well and I was able to measure temperature with it. However, my excitement dissipated all too soon and I felt disaster looming. Simply measuring temperature was not nearly enough. The most critical requirement was not just to make a thermometer, even an accurate one, but to make a practical thermometer. First of all, sticking one’s tongue out was not practical from any point of view… This was a totally unacceptable design and I had no desire to show it to anyone. Demonstrating such a prototype would surely be a suicidal move. I felt discouraged and did not know what to do. I had found a way to design a fast and inexpensive thermometer, but my design was nothing more than a totally useless gadget.
I was worried and confused. I had made a promise to my investors and they had trusted me, but now I had no idea how to proceed further… I thought about it day and night. The days went by and I still had no answer…. In my dreams, I saw invisible infrared rays shooting in all directions. I tried many other versions of the design. Naturally, in the laboratory I was my own guinea pig. With the various prototypes we built, I measured temperature in all parts of my body, hoping that some other site could be used instead of the tongue. I considered taking a temperature at the neck, the nasal cavity, the eyeball, the temple (which would be okay only for bold people). Some of these places correlated with an oral temperature better than others, but still the difference was quite significant…
One day I thought about the ear canal….