title: Small-area low-power heart condition monitoring system using dual-mode SAR-ADC for low-cost wearable healthcare systems.
abstract: BACKGROUND
  Heart rate monitoring is useful to detect many cardiovascular diseases. It can be implemented in a small device with low power consumption, and it can exploit low-cost piezoelectric pressure sensors to measure heart rate. However, it is also desirable to transmit heartbeat waveform for emergency treatment, which significantly increases transmission power.
  
  
  OBJECTIVE
  In this paper, a low-cost wireless heart condition monitoring SoC is proposed. It can monitor and transmit both heart rate and heartbeat waveform, but the hardware is extremely simplified to achieve in a small package.
  
  
  METHODS
  By slight modification of successive-approximation analog-digital converter, it can count heart rate and read out heartbeat waveform with the same hardware. In the normal mode, only an 8-bit heart rate is transmitted for power reduction. If the heart rate is out of a given range, it goes to the emergency mode and a 10-bit heartbeat waveform is transmitted for fast treatment.
  
  
  RESULTS
  The fabricated chip size is 1.1 mm2 in 0.11 μ m CMOS technology, including the radio-frequency transmitter. The measured power consumption is 161.8 μ W in normal mode and 507.3 μ W in emergency mode, respectively.
  
  
  CONCLUSIONS
  The proposed SoC achieves low-cost, small area, and low-power. It is useful as part of a disposable healthcare system.
authors.affiliation: Dongwoon Anatech, Seoul, Korea.
authors.forename: Young-San
authors.initials: YS
authors.lastname: Shin
authors.affiliation: Soongsil University, Seoul, Korea.
authors.forename: Jae-Kyung
authors.initials: JK
authors.lastname: Wee
authors.affiliation: Soongsil University, Seoul, Korea.
authors.forename: Inchae
authors.initials: I
authors.lastname: Song
authors.affiliation: Soongsil University, Seoul, Korea.
authors.forename: Seongsoo
authors.initials: S
authors.lastname: Lee
mesh_terms: D015716:Electrocardiography, Ambulatory / Q000191:economics* / Q000295:instrumentation*; D004867:Equipment Design; D006339:Heart Rate; D006801:Humans; D058998:Remote Sensing Technology / Q000191:economics* / Q000295:instrumentation*; D012815:Signal Processing, Computer-Assisted
keywords: Heart rate monitoring; SAR-ADC; dual-mode; low-power; wearable healthcare system