RESUMO
Delta-E effect sensors are based on magnetoelectric resonators that detune in a magnetic field due to the delta-E effect of the magnetostrictive material. In recent years, such sensors have shown the potential to detect small amplitude and low-frequency magnetic fields. Yet, they all require external magnetic bias fields for optimal operation, which is highly detrimental to their application. Here, we solve this problem by combining the delta-E effect with exchange biased multilayers and operate the resonator in a low-loss torsion mode. It is comprehensively analyzed experimentally and theoretically using various kinds of models. Due to the exchange bias, no external magnetic bias fields are required, but still low detection limits down to [Formula: see text] at 25 Hz are achieved. The potential of this concept is demonstrated with a new operating scheme that permits simultaneous measurement and localization, which is especially desirable for typical biomedical inverse solution problems. The sensor is localized with a minimum spatial resolution of 1 cm while measuring a low-frequency magnetic test signal that can be well reconstructed. Overall, we demonstrate that this class of magnetic field sensors is a significant step towards first biomedical applications and compact large number sensor arrays.
RESUMO
In a prospective study of 30 total hip or knee joint arthroplasty patients, the use of the patient-controlled analgesia (PCA) pump was evaluated for patient acceptance and relief of pain. In 30 patients, (average age, 72.5 years) excellent analgesia was obtained with the PCA machine without the side effects of conventional intramuscular dosing. PCA was enthusiastically received by nurses, physicians, and patients, and it has become the method of choice in the author's hospital.