Principles

• Have Revised

Application of Biomedical Electronics¶

• Monitoring - of biological / physical signals e.g heart rate, glucose, etc...

• Diagnosing - certain conditions e.g DNA mutators, cardiac arrhythmia

• Replacing - biological function e.g artificial organs, limbs

• Stimulating - certain organs e.g deep brain stimulation, pace maker

Must-haves:¶

• Unobtrusive - Small in size and easy to use
• Ultra-low power consumption - Long battery life
• 24/7 monitoring / local processing - Immediate response for critical conditions
• Wireless - Transparent to user, autonomous
• Low cost - Disposable, mass deployment

Biomedical Electronic Systems¶

Now lets have a look at a general system...

• Measurand – The physical quantity, property or condition that the system measures. eg. bi-potentials, chemical concentrations, pressure, displacement.

• Sensor – Transduces energy from one form to another. Conveys physical measurand to an electrical output. e.g pH/glucose sensor, accelerometer, ECG instrumentation.

• Signal Conditioning – Treat the signal for to enhance detection, further processing and communication. e.g Amplification, Filtering, Analogue to digital conversion

• Auxiliary Elements – Calibration signal with the properties of the measurand. Can elicit the measurand, adjust sensor and signal conditioning blocks. e.g Dynamic range adjustment, resolution.

• Feedback – Application of stimulus, electrical/chemical to the body. Can be either a result of a trend in the measurand or a time-based therapy. e.g Electrical stimulation, Drug infusion.

• Data Transmission – Transmit the information from the body/device for further use. e.g Wireless, wired to a screen.

Design Considerations for Medical Devices¶

Types of Medical Electronics¶

Bench Tops:

• Diagnose a sample after extraction
• Used in dedicated labs
• e.g DNA sequencing, blood gas analysers, ultrasound

Handheld Electronics:

• Small scale diagnostic / monitoring machine
• Portable
• e.g blood glucose meters, point-of-care diagnostic devices

Lab-On-Chip:

• Typically uses semiconductors integrated with micro-fluidics to analuse samples on the small scale
• Can achieve mass integration via large scale sensing arrays
• e.g DNA sequencing

Wearable Electronics:

• Typically worn on body and monitors a specific condition or vital sign
• Needs to be unobtrusive
• e.g heart rate monitor, blood oxygen reader (oximeter), etc

Injestable / Swallowable Electronics:

• Transient implant capable of monitoring, imaging and delivering drugs
• Due to size constraints, power is sent inductively
• e.g Pill cameras, chemical sensors

Implanatable Electronics:

• Typical for long-term to monitor / stimulate for a chronic condition
• Invasive procedure required
• Typically rechargable battery
• e.g pace makers, neural probes, etc...

Prosthetics:

• Artificial device extension that replaces a missing body part
• Can be implanted
• Typically coupled with sensory information