Silicon Locket for Cardiac Monitoring

Introduction

The Silicon Locket is an efficient and high performance medical device for cardiac patients with state-of-the-art electronics, embedded into an ultra small form factor, and thus the name 'locket'. The system is a web enabled heart monitoring device with a host of advanced features to accelerate modern treatment schemes. The subject may stay at home/ hospital and is supposed to wear a match-box size silicon locket with the electrodes strapped at proper locations, and he/she may be at home or in hospital.

Features

The device is optimized to acquire three simultaneous electrocardiogram (ECG) data and stores it in Micro SD card memory. The locket is equipped with an USB, IrDA, RS232 and 2.4GHz direct sequence spread spectrum wireless connectivity for seamless integration with the public network, existing mobile phones and highend PDAs. An ultra low power custom front-end IC (64-pin LQFP) for ECG signal conditioning is implemented in the analog section. The chip is designed, characterized at IIT Bombay and the silicon is fabricated through TSMC Taiwan. The reconfigurable analog circuit may be switched among twelve possible leads. A miniaturized and pluggable PSTN modem is constructed to transfer data to a remote doctor's computer or medical database. In case of abnormality (such as arrhythmia) in the patient's ECG, the silicon locket automatically connects to a mobile phone and sends an alert SMS to the doctor. A low cost polymeric accelerometer (MEMS) is fabricated using electron beam lithography technique, which is useful to detect motion artifacts in ambulatory subjects. A varied model of the silicon locket with an attractive colour STN LCD is designed for easy user interface. Also an interactive GUI is developed for upload and viewing of the stored data through a personal computer.

A 32-bit ARM7 system- on-chip based base station is designed as an accessory for the silicon locket. The base station is a handheld system with a colour TFT LCD and high processing bandwidth. The circuit primarily targets bridge applications for TCP/IP connectivity and for disease detection in greater detail. Complicated signal processing algorithms are expected to run on the base station PCB and those are under development. The commercial versions will be ported with an online disease detection schemes for added patient safety.

" IIT Bombay sets an example of 'cardionet' concept with several added functionalities" The system accelerates cardiac telemedicine application with wearable computers. The latest version of the silicon locket senses skin temperature, body posture and pulse oximetry, apart from ECGs.

Source: Industrial Design Centre
Indian Institute of Technology Bombay
Powai Mumbai 400 076