You probably don't realise it but when you are playing you hold your pick (or plectrum) in a million different ways. The angle between the pick and the strings, the length of exposed pick and how hard you squeeze the pick all affect the sound you will get. How you hold your pick eventually becomes a sub-conscious thing: difficult to describe but crucial to the sound you get.
A good description of this comes from B.B. King , the master of expressive blues playing, who described his pick technique like this:
"I play mostly downstrokes which is why I'm not very fast - with a medium pick. I hold it with my thumb and index finger, and control it with my middle finger. I attack the strings harder than most people. At times I fight the strings for presence to get that force.
Most of the time I don't hold the pick completely flat against the strings. I turn it so that it has a bit of an angle. When I want to mellow out, I hold the pick this way and get midway between the end of the neck and bridge. But when I want a real staccato sound, I play near the bridge and hold the pick flat.
I take the extra effort to make sure I'm hitting the string where and how I want to hit it. It's almost like playing pool: You're going to use a certain bit of English."
Roy Vanegas has taken a fresh look at the pick, with his MIDI Pick device. Conventional guitar-MIDI interfaces encode the pitch and dynamics of the strings. The MIDI Pick contains a pressure transducer which allows you to send MIDI signals simply by squeezing the pick.
The device has two modes. Mode one simply measures how hard you are squeezing the pick and would allow you control a midi effect (e.g. squeeze harder to get more echo). In the second mode the pick acts as an on-off switch, usefull for triggering samples or sounds.
The MIDI Pick uses force–sensing resistor cast inside a custom-made pick. This resistor is wired to a wrist worn box, containing a microcontroller, battery and bluetooth module. The microcontroller then transmits the pressure information wirelessly to any bluetooth–enabled computer.
This sounds like a great idea and a truly innovative concept. I would need to try one myself to be convinced of the advantages over a conventional foot switch. It might also be tricky to coordinate the pick-pressure changes of normal playing with the pressure changes required for the MIDI effects, but it's maker has already used it in performances.
The photo is from a prototype of the MIDI-pick, presented at an experimental music conference , the latest versions are more professional looking.
The B.B. King quote is from the book: Guitar Player Sessions: Licks & Lessons from the World's Greatest Guitar Players and Teachers. Andy Ellis, 1998. Backbeat Books. ISBN 0879305037