A revolution in biomedical semiconductor technology is in process, based on the development of 3D integrated circuits (IC). Novel mask-less photolithographic technology has made it possible to map IC onto the surface of single crystal silicon microspheres as small as 0.5 mm. Over 90% of the spherical surface of a 1 mm diam. IC has been mapped, providing 3 times the area available for planar IC mapping. Continuous copper circuit windings have been fabricated on the surfaces of these microspheres, making high inductance R-L-C circuits feasible. Thus wireless, two-way RF communication with microcircuitry implanted within the body is permitted. 3D IC fabrication is achieved in a continuous process, avoiding expensive planar chip wafer foundries. Many types of biomedical microsensors are feasible. Shown is a 1.1mm 3D accelerometer, with a floating ball centered electrostatically within a spherical annulus. Ball displacement by acceleration force in any direction (fluid flow, muscle contraction, etc.) is sensed by a 6 pole capacitance bridge: three pole regions are depicted in the figure. An RF microsphere amplifier with built-in spherical coil antenna (not shown) attaches to gold bumps at the bottom of the sensor. Microsensors of this type may improve the monitoring and control of artificial internal organs.
ASJC Scopus subject areas
- Biomedical Engineering