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Inventor Series: The Force Sensing Resistor with Franklin Eventoff

Written by Butler Technologies | March 05, 2020

Inventor Series: The FSR with Franklin Eventoff

If you could invent one specific thing, what would it be? This simple question has led to the creation of thousands of innovative products throughout the years. For Franklin Eventoff, that specific thing was the force sensing resistor (FSR), and his life has revolved around its creation ever since. 

It Started with a Quest for Music

Franklin Eventoff grew up with a passion for music. Growing up, he played in a band where he took on vocals and the woodwinds. He also wanted to create a toy for his daughter that would change pitch as pressure was applied and released. At that moment, he quickly discovered the need for a force sensing resistor, so he set out on a journey to find it, unsure what it may have been.

He experimented with resistors and eventually created his first version of the FSR from pencil lead that he placed over interdigitated silver fingers. A force sensing resistor is a thin, flexible material made with layers of carbon and silver ink whose resistance changes when a force, pressure, or mechanical stress is applied.

It was in the late ’70s that Franklin launched his first product into the market. It was a musical toy he developed, which he named, “The Magical Musical Thing”. It was a toy for children that had a keyboard where every button played a different pitch, thanks to FSR’s creation. The product ran with a company known as Mattel Electronics, but by 1981 the electronics market had saturated, and Mattel Electronics quickly lost its place in the market. This left Franklin eager to find his next opportunity, and by 1981 he licensed the “electronic orchestra”, which was an instrument line, to Milton Bradley, now known as Hasbro.

 

 

The Birth of a Company

He moved to Santa Barbara after working in the musical toy space.  There he formed a new company called Interlink Electronics.  After venture capital investment in Interlink, he moved on and continued to create more musical instruments thanks to the FSR.

In 2001, Sensitronics was born. Sensitronics is the leading provider of electronic force sensor technology. Sensitronics aims to make the devices in our lives more interactive and expressive with innovative membrane sensor solutions.  The solutions are cost-effective and easy to integrate. To date, Sensitronics has delivered hundreds of custom sensor designs to clients representing a wide range of industries, from medical and automotive to music and wearables.

 

 

Sensitronics is run by a small team of technical individuals. He stated that he prefers his company to remain small.  As a technology company, he “doesn’t ever want to have a large company or to have a factory”. He thinks of Sensitronics as a company that “takes on challenges others can’t accomplish”.

In today’s music industry, FSRs are used within instruments in several ways. They’re being used to monitor touch control, pitch, and timbre. The FSR is sensitive enough that it can even monitor how hard you’re blowing into an instrument.

“FSRs are in space!”

While Franklin created the FSR for the sole purpose of musical instruments, he never imagined all the markets and applications of the FSR today. When asked about unique applications he has seen the FSR used for, he said there were far too many. Examples he gave us were things such as FSRs being enabled into the lines of a tennis court to monitor the ball and whether it was in or out of the boundaries during a game.

Other unique applications for the FSR are their use in measuring passenger occupancy in vehicles, for robotic seats in space, and within hospital beds. The application opportunities for the FSR are endless, and new applications and uses are being discovered daily. When asked how many varying designs he’s worked on over 45 years, he replied, “Thousands.  I’ve worked on thousands of designs. Literally.”

Innovation

Sensitronics provides FSRs for innovators. “We make them — available so that people can use them and explore the technology.  We try to support that effort in a big way. I realize that I want to pass this on and share this (technology) with as many people as I can.”

He was also quick to advise innovators and inventors to always use NDAs (Non-Disclosure Agreements). “Don’t feel guilty to ask people to sign NDAs.” It’s not a sign of distrust; he stated that he once felt guilty about himself. NDAs ensure the safety and secrecy of your product and your idea. Other than that, have faith in the process. Nothing happens in a day, so trust the process and enjoy the ride!

When asked if there were any advice Franklin would like to provide to current innovators and inventors, he wasn’t short on answers. He stated, “It’s all about persistence and never giving up.” If you have a product that you truly believe in, others will eventually believe in it as well. He also stated, “You can’t do it all on your own, so be open to advice.” This is essential to being successful.