AAWSAP DIRD, Biosensors and BioMEMS: A Survey of the Present Field, March 2010

This Defense Intelligence Reference Document, dated 31 March 2010 and numbered DIA-08-1003-020, was prepared by the Defense Intelligence Agency's Defense Warning Office under its Advanced Aerospace Weapon System Applications Program. It surveys biosensors and biomedical microelectromechanical systems, covering brain-implanted micromachine neuroelectrodes, drug-delivery pumps, glucose sensors, neural interfaces, retinal prostheses, microfluidic lab chips, NASA cell-culture systems and microcantilever sensors. It concludes that the field is expanding rapidly, with nanomechanical systems expected to follow.

From the source: Release of 2026-09-18 Incident: 3/31/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys biosensors and BioMEMS, a broad class of miniature biomedical devices that combine microscale engineering with sensing, fluid handling, stimulation, or drug-delivery functions. The report reviews major application areas including implantable blood-chemistry sensors, neural interfaces, neurostimulation, drug-delivery pumps, microfluidic systems, and emerging nanoscale extensions of the field, while emphasizing that miniaturization can improve sensitivity and enable functions that are difficult or impossible at larger scales. However, it also makes clear that practical development is constrained by biocompatibility, long-term stability, sensor drift, device degradation inside the body, and the high regulatory burden associated with implantable medical systems. The document presents BioMEMS as a rapidly growing and productive field whose future advances are likely to come through continued improvements in fabrication, materials, and reliability.

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Figure 4 illustrates the basic physics where the force is generated. A voltage V, is
applied to the horizontal sliding shaft. There arises an electrical field (shown as the
curved arrow) that tends to pull the shaft into the cavity between the two outer combs.
This is the basic motive force of the device. The force generated by each comb is very
small so there are constructed many sim ilar structures that form a comb-array. All of
the forces act in parallel.
(1)
V
(3)
Figure 4. Illustration of the Basic Physical Principle of the BioMEMS Motor (Muthuswamy et al.)
The device is fabricated by using Sandia's Ultraplanar Multi-level MEMS Technology
(SUMMiTV) process, a 5-layer polysilicon micromachining technology. The layers are
chemically sensitive to different processes and can be selectively removed by etching
with different reagents.
For example silicon can be removed
using an etchant which preferentially
removes silicon only along certain
crystalline planes. Other layers can be
undermined through the use of acids.
The components of the micromachine
are patterned on the silicon using
photoresist masks. A mask is a covering
which prevents parts of the silicon from
being etched away. Figure 5 gives an
idea of the sophistication of this MEMS
fabrication technique.
The end result is that the long rod at
the right of the picture in Figure 3
moves up and down with a speed of
about 1-2 mm per second. The speed
can be adjusted through the number of
teeth designed on the reduction gears.
Single unit recordings were obtained from the somatosensory cortex of adult rats over
a period of three days demonstrating the feasibility of th is technology. This device has
been implanted in rats and its development supported by the neuroprostheses program
of the US National Institutes of Health.
Fluidic BioMEMS
The application of microscale fabrication techniques has allowed the manipulation of
very small volumes of fluids on the nanoliter and even picoliter scales. This allows
6
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Figure s. Close-Up Views of the Micro-Motor Gears
(Sandia National Labs)