Date: 01/02/2017

Medical Electronics design: MEMS in Healthcare

by Vishal Goyal, Technical Marketing Manager, ST Microelectronics India

Healthcare has emerged as one the biggest and fastest growing Industry around the World. The growing importance of Human life, increase in individual disposal income and awareness of preventative measures are driving the growth of this Industry. Increase in life expectancy and ageing of world population has made Healthcare as a very lucrative Industry.

MEMS has evolved as one of the most revolutionized Semiconductor components in personal Healthcare. The advent of MEMS is opening new ventures of application in Healthcare. This article will address some of the applications MEMS in medical electronics system design to serve the healthcare needs.

Semiconductor in Healthcare
Semiconductor is one of the Key drivers of innovations in Healthcare Industry. Semiconductor are used in core medical electronic Instruments such as CT scan, X-ray machines, ECG, Ultrasound, Blood pressure and Glucose monitoring etc. Semiconductor plays function such as sensing, signal conditioning, data conversion & processing, controlling the machines & robots etc. Semiconductor is equally important in medical infrastructure such as setting up of Internet, display, data processing, signal transmission etc. Semiconductor is also driving the growth of personal healthcare as it has enabled to resize the complete system into a handheld device. MEMS is one of the most important innovations in making healthcare personal.

Healthcare requirements in India
It is estimated that by year 2025 190miilion Indians will be at least 60yrs of age. Moreover, as the living standard is increasing higher percentage of people will belong to middle income group. As more women are entering the workforce the purchasing power of household will further boost. The cumulative effect will lead to dramatic growth of Indian Healthcare Industry. Moreover, in developing countries such as India the infrastructure is not keeping pace with growth of population so Individuals need to keep track of health themselves. As most of the population in India still lives in rural and remote locations, there is growing need of telemedicine where a doctor can monitor and diagnose patients remotely.

MEMS – A quick introduction

MEMS or Micro Electro Mechanical Systems are Semiconductor Ics that have combined the electrical and mechanical property of Silicon. There are actual moving mass, springs, cavities, dampers etc inside a MEMS structure. MEMS can detect motions such as acceleration, gravity, angular motion, magnetic field and pressure etc. A typical MEMS is SIP (system in package) IC consisting of two Ics. First IC senses the desired parameter and converts it into equivalent capacitance. Second IC converts the capacitance into equivalent voltage or digitally onto I2C bus.

mems in health

MEMS in Healthcare Industry

MEMS evolution in Healthcare
Bulky and centralized hospital equipments now have a new substitute – handheld personalized healthcare equipments. As firsthand healthcare is shifting from Hospitals to individual, the need of miniaturization, cost-effectiveness, robustness and battery operation has evolved. After creating a new wave of revolution in consumer and mobile phone Industry, MEMS is all set to give healthcare a new definition. Some typical applications of MEMS in Healthcare are pedometer, blood pressure monitoring, ECG, hearing aids etc. MEMS can also be used in complex procedures such as DNA Analysis.

Motions MEMS such as accelerometer have made it possible to accurately measure motion by consuming minimal power with a very compact form factor. As MEMS can detect both linear and angular motion in all 3-axis, a complete inertial state of body or body part can be detected. MEMS can be used in not only wearable device such as pedometer or mobile ECG machine but also penetrative gadgets such as blood pressure monitors or miniaturized robots.

Many semiconductor companies are rolling out products which can be used in healthcare Industry. STMicroelectronics, the world’s leading supplier of MEMS sensors for consumer and portable applications, is particularly very dedicated on Healthcare Industry and has introduced products such as Lab on Chip and Body Gateway products.

Application of MEMS

1. Pedometer
Pedometer is perhaps one of the simplest application yet very useful application of MEMS. MEMS can detect the jerk body is facing while a user is running or walking at each step. The jerk experienced by MEMS IC is shown in Fig 2.This feature can be used to accurately number of steps taken. MEMS can be used to calculate Step count, Speed, Distance, Calories. Some parameters such as step length, height and weight may be needed for calibration. Accurately Pedometer can be developed keeping in mind the locations where user is wearing them (attached to belt, shirt/pant pocket etc). A 3-axis accelerometer can detect acceleration in all the three axis so a single MEMS can detect the change independent of the way pedometer is worn by the user. MEMS can also be used to detect the swing in centre of gravity of person. This data can be used by doctor to suggest the right posture or even wear right equipment to the patient.

2. Hearing Aid
MEMS microphone has made it possible to make small size hearing aid with high sound quality, reliability and affordability. MEMS microphones meet price points set by the traditional electret condenser microphones (ECM), while boasting superior reliability and robustness. ST has introduced MP45DT microphone which is inherently less susceptible to mechanical vibration, temperature variations and electromagnetic interference. The sensing element, capable of detecting acoustic waves, is manufactured using a specialized silicon micromachining process to produce audio sensors. MEMS microphone based hearing aid can be designed in such a way that it becomes invisible to external world thus avoiding apparent social issues.

3. Early Diagnosis of Glaucoma

MEMS microphone and a transmitter antenna when mounted on a 24-hour silicon disposable lens can be used for early diagnosis of glaucoma. As the MEMS sensor is ultra miniaturized, it can be mounted at the peripheral of lens without impacting normal viewing. Also a small antenna will transmit relevant data to the receiving station. The Sensor is capable of measuring cornea deformations due to Intra-Ocular-Pressure (IOP) variations. The IOP Sensor is a wireless sensor that acts as a transducer, antenna and mechanical support for additional read-out electronics. This information can be monitored and analyzed by Hospital to take necessary action and diagnose glaucoma in its early stage.
glaucoma treatment

4. Blood Pressure
The human circulatory system generates pressure which can be measured by miniaturized and biocompatible BioMEMS. The generated pressure is complex and varies by a large value and change by the current situation of human body so it require very specific MEMS to do the task. The BioMEMS can be inserted into the body and moved to the specific places near the heart. By measuring pressure gradients across heart valves, doctors can access valve disease. It will be to diagnose and monitor heart failure and measuring cardiac output.

5. Body Gateway
Body gateway is a wearable device used for measuring physiological parameters such as ECG, heart rate, breathing rate etc. It can also detect person’s movement and if there is a abnormal movement such as falling down on floor can be detected. The measured data or alarms can be sent via Bluetooth to internet gateway device which can send the data to Hospital control rooms. MEMS is the key enablers for this, it can detect person movement and change is blood pressure to measure the breathing rate. The small size and ultra low power consumption has made it possible. This application of MEMS can also lead to revolution of telemedicine where hospitals can monitor patients in real time scenario and take necessary action remotely. It can also reduce the cost of treatment drastically as patients no longer have to admit in Hospitals for monitoring reliable information.

mems in body motion

Lab on Chip
Lab-on-a-chip allows small amounts of bodily fluids to be tested in seconds. All chemical reactions occur inside the biochip’s buried channels or on its surface. And because the cartridge that carries the chip is self-contained and disposable, the system strongly reduces the cross-contamination risks of conventional multi-step protocols. The ST Lab-on-chip is designed to handle micro fluidics and some of the knowledge is based on expertise in MEMS inkjet printer chips. The Lab-on-chip can amplify or multiply DNA sample in approx 15 minutes thus requires very small amount of fluid, saves time and is economical.

MEMS has opened many new avenues for healthcare and made it possible to a wider section of society. By monitoring many key parameters it has one of the prime enablers of telemedicine where patient in far off areas can get the best available treatment at much lower cost. MEMS has also made it possible to monitor the patients in real time without admitting in the Hospitals. MEMS is driving the revolution of growth of Healthcare Industry and ST is a major player which is driving this growth. ST’s strong presence in MEMS market and strategic focus on MEMS will bring many more Healthcare applications under the MEMS parameter to make Healthcare better, economical, less time consuming and more acceptable.