Bioelectrical impedance measuring system
US3971365A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 12, 1973 |
| Grant date | Jul 27, 1976 |
| Priority date | — |
| Expiry date | Feb 12, 1993 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B2018/00875
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A bioelectrical impedance measuring system that measures and indicates the impedance of a biological subject, such as one or more human extremities. The system measures and indicates a basal impedance value of the measured subject, and also indicates short temporal variations in the basal value. In the system an excitation signal, derived from an electrical signal source, is coupled to the subject by excitation electrodes and a resulting subject output signal is sensed by receiver electrodes. The subject output signal is electronically subtracted from a reference signal derived from the signal source, and the resulting signal is used to drive a display unit. The system includes a null detector connected to the display unit input, and an automatic gain control unit responsive thereto, connected in the subject output signal path to automatically maintain the system in a nulled condition. With the output of the system adjusted to a null condition the value indicated is proportional to the basal impedance of the subject. The automatic gain control unit includes a lock function generator to hold the variable gain at an instantaneous null establishing a basal value for a desired measurem…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.