IMEC Tech Forum: MEMS for brain implants, cancer-testing lab-on-a-chip, wireless EEG

October 9, 2009 – IMEC’s annual IMEC’s annual Technology Forum this week featured three announcements targeting medical devices: a low-power MEMS actuator for in-vivo biomedical applications, a microfluidics device for faster cancer detection and therapy, and a new wireless EEG system for ambulatory monitoring.

"Inchworm" actuator for in-vivo biomed

An ultralow-power, watertight actuator newly developed by IMEC targets applications requiring long autonomy with small batteries, and is "especially suited" for in-vivo biomedical applications such as brain implants, the R&D consortium says.

The new silicon-on-insulator (SOI)-fabricated device is an "electrostatic inchworm actuator" that converts energy into micromovements — by moving in concert, four arms that selectively latch/unlatch and two for driving can achieve a bidirectional step-like movement. The device has a range of ±50μm and can generate sufficient force (±195μN) to position, for example, in-vivo brain electrodes, with 3× lower operating voltage (11V) than current actuators, and it also consumes just <100nW of power. The device has been integrated with a microneedle encapsulated in a flip-chip package with a glass cap and hydrophobic surface treatment (i.e. it’s watertight).

 

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Figure 1. Schematic (top) and micrograph (bottom) of IMEC’s inchworm actuator, with six pull-in actuators (four for latching and two for driving). By proper latching, unlatching, and driving the shuttle, the actuator can drive a bidirectional step-like movement. (Source: IMEC)

Micro-actuators are already used in medical applications requiring microscopic-scale control of biological objects or environments — e.g. for microsurgery tools, pumps, and needles. One application is to integrate the actuators with microprobes for brain applications, for accurately controlling the position of microneedles, so as to reach and get near the correct groups of neurons for a specific disorder to obtain the best signal/noise ratio. These would be true "implants" in the sense of the word; today’s "implants" using actuators for brain research are actually placed outside the body.

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Figure 2. Schematic (left) and actual photo (right) of the actuator, encapsulated with a micro-needle in a watertight package. (Source: IMEC)


Lab-on-chip targets breast cancer

Under the European Union’s MASCOT ("Multiple-access space-time coding testbed") project which pursues "novel techniques" for multiple user/input/output wireless systems, IMEC and partners have put together a modular platform with autonomous modules which can be used for different medical applications — in this case, detection and therapy evaluation of breast cancer.

This particular device — the first to include many complex sample preparation steps and multiplexed detection, according to IMEC — includes one module for mixing blood samples with magnetic beads that bind to tumor cells, and another module to isolate and count those cells using dielectrophoresis and magnetic sensing. In the third "amplification" module the tumor cells are destroyed and the genetic material extracted using multiplex ligation dependent probe amplification. Specific assays amplify ~20 markers associated with breast carcinoma cells, which are detected using an array of electrochemical sensors.

Having a multifunction lab-on-a-chip device would solve timeliness and cost issues associated with cancer detection, IMEC explains. In the case of breast cancer, only 2-3 tumor cells are found in 5ml of blood; many sample preprocessing steps in different medical instruments are required to make full analysis. A lab-on-a-chip system incorporating the above-described functions would vastly simplify this process, which could be performed in a doctor’s office or near a patient’s bedside.

The system has been validated on "spiked blood samples" and modules are ready for "further hetero-integration into a single lab-on-chip," IMEC notes. Next is to clinically validate it in a breast cancer therapy study in Oslo.

Wireless EEG

IMEC and research affiliate Holst Center have developed a miniaturized wireless EEG system for remote monitoring of patients in their daily environment; the result is seen to be more natural readings and more comfortable patients.

The system incorporates an eight-channel ultralow-power analog readout ASIC, with other electronics including radio and controller integrated onto a 47×27mm printed circuit board, packaged in a "small box" with status LEDs, a switch button, and interfaces for din32 cables. The whole thing requires only 1.8mA of power, meaning about three days of operation on one 160mAh lithium ion battery.

The system can connect to individual electrodes, recording high-quality signals via gel electrodes (R&D on dry electrodes is still ongoing), standard EEG monitoring hats, or other proprietary EEG headsets. Data is wirelessly transmitted in real-time to a receiver up to 10m away. IMEC also has developed algorithms to interpret the brain signals, "linking the brain activity to the degree of relaxation," the group said in a statement.

The new wireless EEG is part of an art expo, dubbed "Staalhemel" ("Steel sky"), at the center STK in Leuven, Belgium, in which visitors wearing a headset with IMEC’s EEG system walk past 80 steel plates suspended above; the brainwaves activate tiny hammers to tap rhythmic patterns on the plates.

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