An apparatus and method for regulating tissue growth in vivo are provided. The apparatus includes a magnetic field generator and a magnetic field detector for producing a controlled, fluctuating, directionally oriented magnetic field parallel to a predetermined axis projecting through the target tissue. The field detector samples the magnetic flux density along the predetermined access and provides a signal to a microprocessor which determines the average value of the flux density. The applied magnetic field is oscillated at predetermined frequencies to maintain a preselected ratio of frequency to average flux density. This ratio is maintained by adjusting the frequency of the fluctuating magnetic field and/or by adjusting the intensity of the applied magnetic field as the composite magnetic flux density changes in response to changes in the local magnetic field to which the target tissue is subjected. By maintaining these precise predetermined ratios of frequency to average magnetic flux density, growth characteristics of the target tissue are controlled.

A method and apparatus for electrical dosimetry control in the application of electric currents to the human body, dosage being determined by the product of time and electrical current, wherein electrical current magnitude and/or time may be selectively varied by the patient or therapist during an administration procedure, for the comfort or convenience of the patient, without altering the total predetermined dosage to be administered, the system typically including means for setting the desired total dosage to be administered, means for selectively varying the magnitude of electrical current applied to the patient, means for integrating the applied current over time to obtain an electrical current-time product providing a running measure of dosage during the administration procedure, means for comparing the running measure with the total dosage desired, and means for terminating the administration procedure once the desired total dosage has been delivered to the patient.

An apparatus and method for non-invasive sensing of bone healing is disclosed. The apparatus and method uses an electromagnetic field to measure impedance changes at the bone fracture site during the healing process. The impedance change at the fracture site is a direct indication of the mechanical strength of the fracture site.

A PEMF double-transducer system (FIG. 1) used for PEMF therapy (such as after spinal fusion) uses a two-transducer configuration for generating flux-aided electromagnetic fields. The semi-rigid transducers (12, 14) are comformable, anatomically contoured and flat-wound to enhance patient comfort, and incorporated with an adjustable belt (16) to provide bracing. The belt includes compartments for a drive electronic module (22), and a rechargeable battery pack (24), making the system portable. The drive electronics (FIG. 3) includes a PEMF processor (41) that executes a PEMF program for providing pulsing current to the front and back transducers at predetermined intervals, thereby activating the electromagnetic field according to a prescribed PEMF regimen.

An implanted blood pump system is described wherein power for driving the pump is provided by a transcutaneous transformer having an external primary winding and an implanted secondary winding. Control of the driving voltage to the pump is provided by an implanted shunt regulator. Voltage applied to the primary winding is controlled in accordance with the power factor sensed in the primary winding.