Microcontroller-based wireless recorder for biomedical signals.

A portable multichannel system is described for the recording of biomedical signals wirelessly. Instead of using the conversional time-division analog-modulation method, the technique of digital multiplexing was applied to increase the number of signal channels to 4. Detailed design considerations and functional allocation of the system is discussed. The frontend unit was modularly designed to condition the input signal in an optimal manner. Then, the microcontroller handled the tasks of data conversion, wireless transmission, as well as providing the ability of simple preprocessing such as waveform averaging or rectification. The low-power nature of this microcontroller affords the benefit of battery operation and hence, patient isolation of the system. Finally, a single-chip receiver, which compatible with the RF transmitter of the microcontroller, was used to implement a compact interface with the host computer. An application of this portable recorder for low-back pain studies is shown. This device can simultaneously record one ECG and two surface EMG wirelessly, thus, is helpful in relieving patients' anxiety devising clinical measurement. Such an approach, microcontroller-based wireless measurement, could be an important trend for biomedical instrumentation and we help that this paper could be useful for other colleagues.

Weight gain and the sleeping electroencephalogram: study of 10 patients with anorexia nervosa.

The relation between reduced nutritional intake, with consequent weight loss, and sleep disturbance was studied by comparing certain sleep encephalogram patterns in a group of inpatients with anorexia nervosa before, during, and after a regimen of refeeding with a normal diet to a matched population mean weight. At low body weights patients had less sleep and more restlessness, especially in the last four hours of the night. During refeeding and weight gain slow-wave sleep initially increased and then tended to decrease during the final stage of restoration of weight back to matched population mean levels. With the overall weight gain, however, there was a significant increase in length of sleep and rapid eye movement sleep, the latter increasing especially during the later stages of weight gain. These results reaffirm that insomnia, and especially early morning waking, is associated with low body weight in anorexia nervosa, and their implications are discussed with particular reference to a hypothetical association between various anabolic profiles and the need for differing components of sleep.