Inchworm Microdrive System — LSS-8000

Positioning of microelectrodes for electrophysiology recordings require micrometer-scale control of high-velocity, high-acceleration steps. These steps must be achieved with minimum vibration to prevent damage to cells, their processes or connections. For almost 20 years, EXFO has supplied Inchworm® motor systems to help cell physiologists obtain clean penetrations and stable cell recordings.

25 mm travel

Programmable step sizes in 0.5 µm increments

Solid-state construction of PZT motor

High-speed and acceleration

Ultra-low-noise drive electronics

The Inchworm Advantage: Increased Yields

Inchworm Technology
The Inchworm motor is a patented solid-state design that creates linear motion without rotation or gears.

Positioning Precision
The Inchworm motor uses an optical position encoder to directly measure the shaft position with 0.5 µm resolution. Inchworm motors eliminate errors caused by overshoot and backlash in traditional motor systems. Step sizes can be programmed and commanded in any multiple of the encoder resolution.

High Acceleration and Velocity
Clean penetrations require a micropositioner capable of high acceleration and velocity as well as rapid deceleration. The goal is to avoid dimpling or ripping the membrane, which results in severe cell damage. The Inchworm PZT elements respond in microseconds with very high stiffness to achieve high acceleration and velocity. The motor achieves its top speed of 1.5 mm/s within 2 µm of starting. The motor's dynamic velocity range also is important; it can move at any velocity from 1 nm/s to 1.5 mm/s without gear changes.

Minimum Tip Vibration
The Inchworm motor used in this system utilizes a special lateral stability option (LSO) to ensure that lateral movement of the spindle tip is less than 0.2 µm.

Stability
The solid-state ceramic and metal construction of the Inchworm motor provides very high stiffness and low thermal drift. The thermal stability is also enhanced by the zero heat dissipation when the motor is holding position. The closed-loop encoder feedback ensures submicron stability of the electrode tip. Inchworm systems simply hold cells longer!

Ultra-low-noise Controller
The 8200 Controller was developed to provide more than an order of magnitude improvement in EMI noise and improved grounding/shielding. This minimizes interference in electrical recordings.

Model 8005 Handset
Uses push buttons and a potentiometer to control direction, speed, starts and stops. Jog and step mode are selectable. Step size is programmed from the 8200 Controller.