ABSTRACT
A biopotential amplifier for single supply operation is presented. It uses a Driven Right Leg Circuit (DRL) to drive the patient's body to a DC common mode voltage, centering biopotential signals with respect to the amplifier's input voltage range. This scheme ensures proper range operation when a single power supply is used. The circuit described is especially suited for low consumption, battery-powered applications, requiring a single battery and avoiding switching voltage inverters to achieve dual supplies. The generic circuit is described and, as an example, a biopotential amplifier with a gain of 60 dB and a DC input range of +/-200 mV was implemented using low power operational amplifiers. A Common Mode Rejection Ratio (CMRR) of 126 dB at 50 Hz was achieved without trimming.
Subject(s)
Amplifiers, Electronic , Signal Processing, Computer-Assisted/instrumentation , Electric Impedance , Electric Power Supplies , Electrocardiography , Equipment DesignABSTRACT
Biopotential measurements are very sensitive to electromagnetic interference (EMI). EMI gets into the acquisition system by many ways, both as differential and common mode signals, driven-right-leg circuits (DRL) are widely used to reduce common mode interference. This paper reports an improvement on the classic DRL. The proposed circuit uses a transconductance amplifier to drive the patient's body. This configuration has some interesting properties, which provide an extended bandwidth for high-frequency EMI rejection (such as fluorescent lights interference). The improvement is around 20 dB for frequencies of few kilohertz and the circuit is easy to compensate for stability. A comparative analysis against a typical DRL is presented, the results obtained have been experimentally tested.
Subject(s)
Electricity , Radiation , Electric Conductivity , Electrophysiology , Humans , Models, TheoreticalABSTRACT
A new role has been developed for pediatric nurse practitioners that is home based and provides primary care and case management for chronically ill children. In a pilot program at Children's Hospital and Health Center in San Diego, pediatric nurse practitioners address the complex needs of chronically ill children who require comprehensive care, education, psychosocial support, and coordination of services. This article describes the population, program, and expanded role for PNPs, emphasizing case management, management of chronic illness, minor illnesses, and management of well child care. Clinical impressions of the benefits of the role to the child and family are presented.
