Sensorid elusolendites ja tehnikas

…

Heigo Tark

- Biosensor vs tehniline sensor

definitsioon

- erinevad biosensorid- Kuulmisimplantaat vs kuuldeaparaat

- ‘kuntsnägemine’ vs kaamera

sisu

Sensors – definition

A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument

A Thermistor is a temperature dependent resistor. When temperature changes, the resistance of the thermistor changes in a predictable way

different motion sensors: They inject energy (light, microwaves or sound) into the environment in order to detect a change of some sort

Biosensor – definition

… is a sensor using a living component or a product of a living thing for measurement or indication. Generally a biosensor consists of two parts:

- A bilogical recognition element (enzyme, antibody, receptor) to provide selectivity to sense the target of interest

- A supporting element which also acts as a transducer to convert the biochemical reaction into “signal” that can be read out

Biosensor –

“Receptor” provides selective molecular recognition

For example: enzymes, antibodies, receptors, nucleic acids, polypeptites

Trancducer types in biosensors: calorimetric, electrochemical, optical etc

Biosensor - enzymatic

Enzymes are catalysts for biochemical reactions; larege macromolecules consisting mostly of protein, and usually containing a prosthetic group (metal)

Advantages: - highly selective -Enzymes are catalytic, thus improving the sensitivity- Fairly fast

Disadvantages:-expensive: cost of extraction, isolation and purification- activity loss when enzymes are immobilized- enzymes tend to be deactive after a relatively short period of time

Biosensor - enzymatic

Example:

Glucose sensors

- In an enzymatic biosensor, the enzyme is immobilized as the ‘receptor’- Enzymes are specific to their substrates which can be the analyte

Glucose + O2 + H20 gluconic acid + H202

Measures the amount of O2 consumtion

Biosensor – electrochemical cells

- Typically used for measurements of ion or gas-molecule concentrations- The sensor consist of two electrodes and an ionic conductive material called electrolyte- Operation of electrochemical sensors is based on reactions and their equilibrium at the electrode surfaces (interface between electronic and ionic conductors)

Biosensor – electrochemical cells

Example: Blood oxygen measurementMeasuring arterial blood gases pO2: in operating room and intensive care unit to monitor respiratory and circulatory condition of a patient

Clark electrode: measures partial pressure of O2

Biosensor – oxygen saturation

Oxygen saturation (% of oxygenated hemoglobin) can be measured and used to represent blood oxygenation

Oximetry: (color) measures light absorbance at one wavelength where there is a large difference between Hband HbO2 and at another wavelength (or more wavelengths)

Pulse oximetry: use the pulsatile(AC) component to extract oxygen saturation information and the non-pulsatile(DC) signal as a reference for normalization

Biosensor – oxygen saturation

EAR:

“Designed” to interpreta multifaceted sound pressure wave form in to its individual frequency Components and then reconstitute these components together into what we recognize as blended sound

biological vs “techical” hearing?

Most sounds are complex wave forms consisting of pressure waves of Varying amplitudes and frequencies mixed together into sounds and words that we recognize In our daily lives

The sound from the middle ear is transmitted into the inner ear known as the cochlea. It is here that the complex sound wave forms of varying frequencies and amplitudes are separated into individual components.This is accomplished by means of the resonant frequency for a material based upon its geometry

biological vs “techical” hearing?

As complex sound enters into The cochlea, each relevant section of the cochlea would vibrate at its resonant frequency based Upon its thickness

-Thousands of hair cells that are connected to tiny nerves - As cochlea fibrates at resonant frequency so do the attached hair cells- Hairs connected to nerves, connected to auditery nerve, which sends recombined electrical Signal to brain- The brain translates these impulses into what we experience as sound

biological vs “techical” hearing?

biological vs “techical” hearing?

Technical – hearing aids:

Miniature soundsystems with: - a microphone - Speaker - Audioamplifier - and associated electronics

- Individual patient has an individualized Hearing loss, which can be frequency and amplitude dependent- there are settings for gain at varying frequencies that are preset for each patient

biological vs “techical” hearing?

Technical - Cochlear Implant:

- Extreme hearing loss

- born completly deaf

- deafness through ilness/ injury

- surgically placed implant on the outside of the skull and under the skin just above and behind the ear.- An electrode array attached to the implant is inserted into the cochlea .- After surgery, the user is fitted with external devices—a microphone(1), speech processor (2), and transmitter coil (3)

Cochlear implant bypasses damaged parts of the inner ear and electronically stimulates the hair cells and adjacent nerves within the cochlea.

biological vs “techical” hearing?

-Electronic code is sent to the transmitter coil (3) that is held above the implant (4) by a magnet

-The transmitter coil uses an FM radio signal to transmit the signal through the intact skin into the implant- The implant decodes the signal and sends small electrical pulses to the electrodes (5) in the cochlea, which stimulate the auditory nerves directly.

In response,the auditory nerve carries out its natural function and conducts nerve impulses to the brain.The brain receives the nerve impulses and interprets them as sound

biological vs “techical” hearing?

in United States, medical costs run from US$45,000 to US$105,000;

artificial vs “technical” vision

Artificial-Retina: (very basic principle)

- is a bioelectronic implant

-contains about 3,500 microscopic solar cells that are able to convert light into electrical pulses

-These cells convert light signals to electric impulses that are sent to the optic nerve and the brain

- It receives all of its needed power from the light entering the eye

artificial vs “technical” vision

Cameras (very basic principle):

-Basically an “eye”, that records what is seen

- on a film or digital format vs electric signals in human brain