Design of Coils for Millimeter- and Submillimeter-Sized Biotelemetry

Abstract

Biotelemetric systems, especially those that employ implanted devices, work with inductive links, where usually large circular external coils are separated by relatively large distances (dimensions of centimeters) from the small (millimeter- or submillimeter-size) implanted coils. This paper shows that, under these conditions, a simplified method for calculation of the mutual inductance (M) between the coils, avoiding elliptic integrals, can be obtained. A procedure for coil design, with maximum M between them, is also described.

Optimal Operating Frequency in Wireless Power Transmission for Implantable Devices

“…Most of these wireless interfaces operate below 20 MHz [1]- [3]. Quasi-static analysis was sufficient to analyze these wireless links [4]- [8]. The quasi-static approximation works well at low frequency.…”

Selectable gain amplifier for inductive sensor used to measure human motion

“…Theoretical response was obtained according equation (9) using three stages and output range from 0 to 5 V. Figure 6 shows standard desviation to distances from 4 to 28 cm. The values of 2 and 3 cm are not shown because it presented voltages higher than 5 V. Furthermore, it was verified great discrepancies in short distances because according to Pichorim and Abatti [10], the theoretical model is valid only when distances between coils are gratter than transmitter coil radius. Moreover, there are some significant errors next to 16 cm due discontinuity of function between second and third stages.…”

“…Thus, the distance (d) can be determined by measuring the amplitude of received signal. [10] describe a simplified method to determine magnetic flux density (B) and mutual inductance (M ) in a magnetic link. Assuming that the used coils are coplanar and separation distance (d) is gratter than transmitter coil radius (a), the magnetic flux density can be expressed by…”

“…The theoretical value of mutual inductance (M ) can be obtained by the product of area inside the coil and magnetic flux density [10], yielding…”

A Programmable Microsystem Using System-on-Chip for Real-time Biotelemetry

“…4(a)]. The off-chip TX used a 1 surface mount coil inductor (ferrite core) in its output stage to act as a magnetic coupler, eliminating the need for an RF antenna [26], [27]. Tests indicated that the maximum data rate was 5 kbps and the FSK deviation was 10 kHz.…”