This Small Business Innovation Program (SBIR) Phase I project proposes the development of a low cost, small size and high sensitivity magnetic sensor for continuous monitoring and portable magnetocardiography (MCG) of the human heart. Portable cardiography has been limited to electrocardiography (ECG) sensors for decades. ECG is not suitable for continuous heart-rate monitoring (e.g. for in-home use by elderly patients) since it requires conductive (adhesive) electrodes on the patient's chest. In contrast, MCG can accurately record the human heartbeat non-invasively and contactless. Presently, the MCG market is dominated by superconducting quantum interference devices (SQUID), an ultra-sensitive magnetic technology. However, SQUIDs are large in size, power hungry and high cost, facts that have limited the use of MCG outside the medical research environment. The company proposes a novel, chip-scale, highly-sensitive magnetic sensing device aimed to enter and largely extend the portable ECG heart-monitoring market. The proposed millimeter-scale device combines two different technologies: (a) magnetoresistive (MR) sensors and (b) piezoelectric microelectromechanical systems (MEMS) resonators. Through an innovative noise cancelation mechanism, the outcome of this project will show the capability to reach an unprecedented magnetic field sensitivity limit of approximately 1 pT/rt-Hz at room temperature, enough to measure the 10-100 pT fields generated by the human heart.
The broader impact/commercial potential of this project offers compatibility with existing high-volume, low-cost integrated circuit manufacturing, offering the promise of a very low-cost (< $5) magnetic sensor chip. It has the potential to change the way portable heart monitoring is done today. By 2009 approximately 27 million Americans were living and diagnosed with heart disease. Continuous heart rate monitoring is crucial for these patients. The company provides a low-cost, easy-to-use, and portable device to meet this need. The impact on patients' health will be huge, given that continuous monitoring will improve prevention and early detection of anomalies. Positive economic impact is also expected. In 2005, the cost of heart disease and stroke in the US was projected to exceed $394 billion: $242 billion for healthcare expenditures and $152 billion for lost productivity from death and disability. The proposed device, mainly due to its small dimensions, is also a very interesting tool for MCG scientific research using arrays of magnetic sensors. MCG enables 3D imaging of heart anomalies, crucial for specific heart diagnosis - for example, finding the source of arrhythmias.
This project developed a low cost, small size and high sensitivity magnetometer capable of measuring the magnetic field activity of the heart, targeting applications such as contactless heart rate monitoring and magnetocardiography (MCG) for medical use. Contrary to conventional heart monitors used in sports and in medical diagnosis, our device doesn’t require any contact to the skin, avoiding uncomfortable electrodes, adhesives and chest straps commonly used today in electrocardiography-based devices. Our sensing technology measures heart rate and cardiac waveform by detecting the small magnetic fields generated by the heart, enabling a contactless, "wireless", unobtrusive and comfortable way to evaluate the heart condition. Small size and low power enables its use as a portable device, being easily placed inside a chest pocket or integrated with wearable textiles, while recording the heart activity. Our technology is also a potential candidate to be integrated with wearable electronics focused on health monitoring, such as smart watches and activity trackers. During this NSF SBIR Phase I project we focused on the development and optimization of our magnetic sensor technology, and preliminary demonstration of heart rate readings. Our final sensor prototype achieved a magnetic field sensitivity of 0.9 nT/Hz1/2 at 1 Hz operating at room temperature, improving by three orders of magnitude the sensitivity of our previous generation device. Using this prototype we were able to measure heart rate in a human subject, by placing the sensor within 1 cm of the subject’s chest. We believe this is a groundbreaking result, and a crucial proof of concept towards the development of a contactless heart monitor based on magnetocardiography. During this Phase I project we also developed a high yield micro-fabrication process, which is compatible with existing high-volume, low-cost integrated circuit manufacturing, offering the promise of a very low-cost (< $5) magnetic sensor chip. Additionally, our technology could have impact on public health, with benefits in preventive medicine. Better preventive care will consequently help to lower healthcare costs.
