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IMEC’s ultra-low power actuator suitable for in-vivo biomedical applications
06 October 2009
Interuniversity Microelectronics Centre (IMEC)
IMEC has developed an actuator that runs on ultra-low power and that is watertight. This innovative combination of characteristics makes the actuator especially suited for use in in-vivo biomedical applications, and, in general, for all applications that need to combine a long autonomy with small batteries. IMEC’s prototype has an integrated micro-needle, which can be steered by the actuator.
The new actuator is fabricated using SOI-based (silicon-on-insulator) micromachining. The actuator combines a large range (±50µm) with sufficient force (±195µN) to position for example in-vivo brain electrodes. It works at 11V, which is three times lower than the operating voltages of the current available actuators. Moreover, the actuator consumes below 100nW and can therefore be used in applications that require a long battery life. IMEC has integrated the actuator with a micro-needle in a watertight encapsulation that does not hinder the movement of actuator and needle. The package includes a flip-chip mounted glass cap and hydrophobic surface treatment to prevent water ingress.
A micro-actuator is a MEMS-device (micro-electromechanical system) that converts energy into micro-movements, allowing it to position or control elements with a high precision, and with steps of a few micrometers or even nanometers. IMEC’s actuator is an electrostatic inchworm actuator, having 6 arms that selectively latch, unlatch, and drive.
Today, micro-actuators are already used in medical applications where biological objects or their environment need to be controlled at the microscopic scale. Examples are micro-manipulators, micro-surgery tools, micro-pumps, and micro-needles. One particular biomedical application of micro-actuators is to integrate them with microprobes for brain applications. Today, actuators for brain implants are already used during brain research; but they are placed outside the body. IMEC’s inchworm actuator combines small size with water tightness and a long autonomy, enabling implantation and thus long-term patient treatment. The actuator could be used to accurately control the position of micro-needles used in brain applications. This is necessary to reach the correct groups of neurons for the specific disorder and to get near the neurons for a better signal to noise ratio.
IMEC’s inchworm actuator has 6 pull-in actuators; 4 are used for latching and 2 for driving. By proper latching, unlatching, and driving the shuttle, the actuator can drive a bidirectional step-like movement.
The actuator encapsulated with a micro-needle in a watertight package.