Sensors Hee Chan Kim, Ph.D. Department of Biomedical Engineering, Seoul National University
Sensors & Transducers Transducer : A converter of one type of energy into another 변환기입력신호 ( 에너지1) 출력신호 ( 에너지2) (Transducer) Example) Actuator : energy1 = electrical / energy 2 = mechanical Sensor : A transducer providing an electrical output 센서입력신호 ( 에너지1) 출력신호 ( 전기에너지 ) (Sensor)
Sensors - Definition and Principles - Stimulus/ Measurand Mechanical Thermal Electrical Magnetic Radiant Chemical EtCO 2 Blood Pressure Transducible Transducible Property Property Detection Means SENSOR IR absorption (2.7/4.3/14.7μ) displacement of diaphragm Principle Principle of of Transduction Transduction Conversion Phenomenon 1. voltage, current, resistance, or electric field strength, LED + photodetector 2. easy to handle, 3. many good strain gauge tools are ready, 4. PC Electrical Output
Direct, indirect, & inferential measurements Direct : measurement made of the parameter itself, no interpretation, calculation, interpolation (ex : force & pressure measurement) Indirect : SpO2, NIBP Inferential : cardiac output (indicatordilution measurement)
Sensor characteristics terminology-1 Sensitivity : the slope of the output characteristic curve (Δy/Δx) sensitivity error : a departure from the ideal slope of the characteristic curve range : max and min values of the applied parameter that can be measured dynamic range : total range of the sensor from min. to max.
Sensor characteristics terminology-2 Span(input full scale) : dynamic range of stimuli to be converted by a sensor full scale output (FSO) : the algebraic difference between the electrical output with max. and min. input stimulus saturation : no desirable output with further increase in stimuli (span-end nonlinearity) dead band : insensitivity of a sensor in a specific range of input signals
Sensor characteristics terminology-3 Precision : the degree of reproducibility of a measurement(repeatability, reproducibility) resolution : the smallest detectable incremental change of input parameter that can be detected accuracy : the max. difference between the actual value and the measured value offset : the output exists when it should be zero
Sensor characteristics terminology-4 Linearity : extent to which the actual measured curve of a sensor departs from the ideal curve (ex : % nonlinearity = Din,max / INfs 100 %) Din, max = max. input deviation INfs = max. full-scale input Monotonicity : dependent variable always either increases or decreases as the independent variable increases
Sensor characteristics terminology-5 Hysteresis : capability to follow the changes in the input parameter regardless of the direction response time : time required for a sensor output to change from its previous state to a final settled value within an error tolerance band of the correct new value Dynamic linearity : ability to follow rapid changes in the input parameter; amplitude & phase distortion characteristics, response time Transfer function
Sources of sensor error Insertion error : the act of inserting the sensor into the system changes the parameter being measured (First rule of instrumentation : the measuring instrument must not alter the event being measured by Kelvin) application error : operator-caused characteristic error : inherent in the device itself dynamic error : not respond to rapid changes (ex : thermistor) environmental error : environment in which the sensor is used (ex : temperature, vibration, shock, altitude, chemical exposure..)
Passive vs active sensors Passive : requires an external ac or dc electrical source (ex : strain gauge pressure sensor) Active : provides its own energy or derives it from the phenomenon being measured (ex : thermocouple)
Measurand/ Stimulus Sensor Classification Transducible Property Detection Means SENSOR Principle of Transduction Conversion Phenomenon Electrical Output Stimulus Stimulus Specification Detection Means Conversion Phenomenon Material Field Physical Chemical Biological Physical Chemical Biological Physical Chemical Biological physical sensor chemical sensor biosensor ECG, EEG, EMG Pressure Flow Temperature po2 spo2 Glucose DNA/RNA protein Biological Chemical Electric, magnetic EM wave Heat, temperature Displacement, wave Radiation Radioactivity Thermoelectric Photoelectric Photomagnetic Magnetoelectric Electromagnetic Thermoelastic Electroelastic Thermomagnetic Thermooptic Photoelastic Chemical transformation Physical transformation Electrochemical process Spectroscopy Biochemical transformation Physical transformation Effect on test organism Spetroscopy
Sensors:taxonomies Measurand physical sensor chemical sensor biological sensor(cf : biosensor) Invasiveness invasive(contact) sensor noninvasive(non-contact) sensor Usage type multiple-use(continuous monitoring) sensor disposable sensor Power requirement passive sensor active sensor
Definition of Biosensors SubstancesDetectionTransduction Signal Conditioning analyte (substrate) transducer impurity electronic signal Output biological detection element biolayer High Selectivity & Sensitivity electronics sample nerve cell olfactory membrane brain
History of Biosensor 1956, L.C. Clark : oxygen electrode 1962, L.C. Clark : biosensor concept (electrochemical sensor + enzyme transducers as membrane = enzyme electrode) O 2 + 2H 2 O+ 4e 4OH oxygen electrode GOD Glucose + O 2 Gluconic acid + H 2 O 2 enzyme electrode
Analyte/Substrate Any substance that is consumed or produced in a biochemical process and exists inside human body Diverse examples Ions Gases Drugs Substrates Enzymes Microbiology Sodium Potassium Calcium ph Oxygen Ammonia CO 2 Paracetamol Slaicylate Amphetamine Barbiturates Cocaine Morphine Glucose Cholesterol Creatinine Creatine kinase Amylase Aspartate Aminotransferase Chlamydia Strep A Strep B H. Pylori I.M. Malaria Tuberculosis Hormones Cardiac Markers Proteins Allergy Renal Dysfunction Tumor Markers Viruses hcg FSH LH Prolactin TSH CK-MB Myoglobin TroponinI CRP IgE Micro- Albumin PSA Hemoglobin AFP Ferritin Adenovirus HBsAg HBsAb Rotavirus R.S.V.
Biological Components Can attach/combine to one particular substrate but not to others High selectivity & sensitivity Examples Enzyme Antibodies Nucleic acids Receptors Microorganisms Cell/Tissue/Organ materials
Immobilization Adsorption B B B Microencapsulation B B B Entrapment Cross-linking Covalent bonding B B B B B B B B B
Transducers Electrochemical potentiometric, amperometric, voltammetric, conductometric electrode, FET-based Optical absorption, fluorescence, luminescence, IRS(ATR, TIRF, SPR), light scattering Piezoelectric : QCM, EQCM Surface Acoustic Waves Thermal
Physiomics Cellomics Proteomics Genomics HGP : 1990-2003 BT Boom 신기술붐 1. 융합기술분야 2. 건강 의료기술분야 IT Infra NT Boom All Environment & Energy Aeronautics and Space Technology Medicine & Health Nanoelectronics & Computer Technology Material & Manufacturing NNI: Jan. 2000..Transistor(1947), IC(1958), PC(1980 IBM), Internet(1971 ARPANET), mobile phone(1975, Motorola),
건강 의료와신기술 신기술의대표적인응용분야 신기술의신속한적용에대해보수적시장 신기술적용을위한의료기기분야변화양상 1. 최소침습화 (minimally invasive) 2. 무구속화 (POC, portable, wireless) 3. 초소형화 (microminiaturized) 4. 대량정보화, 신정보화 (IT-based) 5. 바이오화 (biocompatible)
Point-of-Care
Point-of-Care Devices - portable & wearable - www.envitec.com www.sonosite.com www.lifeshirts.com
Point-of-Care Testing Point-of-Care Testing : provision of laboratory testing at the point where patient care is rendered
Point-of-Care Testing ER, OR, ICUs Bed-side Outpatient Clinic Tele-Healthcare Ubiquitous Healthcare Satellite Lab Hand-held Device POCT Tele-care Device Central Lab Home, Office Total Laboratory Automation(TLA)
Thrust of POCT TECHNICAL ISSUES Biosensors BioMEMS/μfluidics Nanotechnology Telecommunication Network ECONOMICAL ISSUES High-cost reagent Sample rareness Low-cost Manufacturing Multifunction High High Throughput Quality Control POCT FUNCTIONAL ISSUES 최소침습화최소침습화 (minimally (minimally invasive) invasive) 무구속화무구속화 (POC, (POC, portable, portable, wireless) wireless) 초소형화초소형화 (microminiaturized) (microminiaturized) 대량정보화대량정보화,, 신정보화신정보화 (IT-based) (IT-based) 바이오화바이오화 (biocompatible) (biocompatible)
Essential Technologies Miniaturized Electro-optic Device Information Network Infra-structure Biomedical Science Biochip Biosensor
Megatrend in Healthcare Device Life Style Well-being Life style - 건강하게오래살기 - 독립적으로즐기며살기 (TONK, DINK) - 건강정보에대한관심고조 다기능화 / 전문화 IT 화 : 경박단소 ( 輕薄短小 ) - 가볍고, 얇고, 짧고, 작은 - 비침습화 (minimally invasive) - 대량정보화 BT 화 - 생체적합적 - 신정보화 Network Policy 치료중심에서예방 / 건강관리중심 - 만성성인병환자증가 - 인구고령화 - 공공의료확충 - 맞춤 / 고급의료서비스에대한 need - 수익확충 / 연구개발투자 / 시장개방 네트워킹 메가트렌드 (Megatrend) 미국의미래학자존네이스비츠의저서 메가트렌드 에서 -OCS, 유래한 PACS, 용어 EMR. 현대사회에서일어나고있는거대한조류를뜻함. 저자는공업사회에서정보사회로, 국민경제에서세계경제로 -Telemedicine( 03, 중앙집권화에서분권화로법제화 ), 계층조직이피라미드형에서망상 ( 網狀 ) 조직으로의변화등 10개항목을들고있다. 즉탈공업화사회, 글로벌경제, 분권화, 네트워크및조직등을그특징으로하고있다 -Smart card, RF-ID
u-healthcare 정의 : 인체의건강관련정보를시간과공간의제약없이 (ubiquitous) 수집, 처리, 전달, 관리할수있게해줌으로써제공되는원격지 의료서비스 (healthcare)
Megatrend in u-healthcare Life Style Device Well-being Life style - 건강하게오래살기 - 독립적으로즐기며살기 (TONK, DINK) - 건강정보에대한관심고조 유민착소 ( 柔敏着小 ) - 유연하고, 빠르고, 지닐수있도록작은 New & Fusion Technology -IT/BT/NT 융합기술 - 한계극복기술 Network Policy 치료중심에서예방 / 건강관리중심 - 만성성인병환자증가 - 인구고령화 - 공공의료확충 - 맞춤 / 고급의료서비스에대한 need - 수익확충 / 연구개발투자 / 시장개방 메가트렌드 (Megatrend) 미국의미래학자존네이스비츠의저서 메가트렌드 에서유비퀴터스유래한용어네트워킹. 현대사회에서일어나고있는거대한조류를뜻함. 저자는공업사회에서정보사회로, 국민경제에서세계경제로 -초고속, 중앙집권화에서인터넷보급분권화로, 계층조직이피라미드형에서망상 ( 網狀 ) 조직으로의변화등 10개항목을들고있다. 즉-CDMA, 탈공업화사회 Wireless, 글로벌경제 LAN, 분권화, 네트워크및조직등을그특징으로하고있다 -Bluetooth, Zigbee
Tele-/U-Healthcare Health Monitoring Physical & Biochemical Physical monitoring ECG, NIBP, SpO 2, temperature, motion, location ------------------- Ion, Gas, Drug, Metabolites, Tumor Marker, Cardiac testing Marker, Virus, etc.. Diagnosis Biochemical Device Wireless Wireless LAN LAN Internet Policy Life Style RF RF Drug Delivery Physical Therapy Bluetooth Bluetooth TM TM Users anywhere Users anywhere Therapy Infusion pumps, Stimulators ----------------------- Mechanical, Electrical, Optical, Thermal, etc.. Sensors Sensors & Monitoring Monitoring Device Device Therapeutic Therapeutic Device Device Network Cellular Network, GPS etc Tele-communication Tele-communication network network Medical Medical Service Service Provider Provider