Thermoelectric power source for electronic medical thermometer

Abstract

ÒЕРМОЭЛЕÊÒРИЧЕСÊИЙ ИСÒОЧНИÊ ПИÒАНИЯ ÄЛЯ ЭЛЕÊÒРОННОГО МЕÄИЦИНСÊОГО ÒЕРМОМЕÒРАВ íàñòîÿщåå âðåмÿ дëÿ ïèòàíèÿ мàëîмîщíîé ýëåêòðîííîé àïïàðàòóðы èñïîëьзóюòñÿ õèмèчå-ñêèå èñòîчíèêè. Нåñмîòðÿ íà íåïðåðыâíîå óëóч-шåíèå èõ êàчåñòâà, îíè âñå жå èмåюò ïðèíцèïè-àëьíыå íåдîñòàòêè: îòíîñèòåëьíî âыñîêèå óдåëь-íыå мàññîãàбàðèòíыå õàðàêòåðèñòèêè, íàëèчèå ñàмîðàзðÿдà, мàëыé ðåñóðñ ðàбîòы, îãðàíèчåí-íыé ñðîê õðàíåíèÿ è ýêñïëóàòàцèè ïðè íèзêèõ òåмïåðàòóðàõ. Êðîмå òîãî, ïðîèзâîдñòâî õèмè-чåñêèõ èñòîчíèêîâ ýëåêòðèчåñòâà -ýíåðãîåм-êîå, дîðîãîå è âðåдíîå дëÿ îêðóжàющåé ñðåды.Вñå ýòî îбóñëîâëèâàåò íåîбõîдèмîñòь ïîèñêà íîâыõ èñòîчíèêîâ ýëåêòðèчåñêîé ýíåðãèè, ëè-шåííыõ óêàзàííыõ íåдîñòàòêîâ. Оñîбåííî ïåð-ñïåêòèâíымè â ýòîм îòíîшåíèè ÿâëÿюòñÿ òåð-мîýëåêòðèчåñêèå èñòîчíèêè ïèòàíèÿ [1][2][3], ïî-ñêîëьêó â цåëîм òåðмîýëåêòðèчåñêèå ãåíåðàòîðы èмåюò бîëьшîé ðåñóðñ ðàбîòы (20-30 ëåò è бî-ëåå), îíè íàдåжíы ïðè èñïîëьзîâàíèè â ýêñòðå-мàëьíыõ óñëîâèÿõ è íå òðåбóюò чàñòîé зàмåíы.Изâåñòíî, чòî òåðмîýëåêòðèчåñêèå мèêðîãå-íåðàòîðы èñïîëьзóюòñÿ дëÿ ïèòàíèÿ мàëîмîщ-íыõ ýëåêòðîííыõ óñòðîéñòâ, ñèñòåм òåëåмåòðèè, íàâèãàцèè, ИÊ-дåòåêòîðîâ, à òàêжå дëÿ ïèòàíèÿ âîåííîé è мåдèцèíñêîé òåõíèêè [4][5][6][7][8]. Одíàêî, íåñмîòðÿ íà ðàзíîîбðàзíîå èñïîëьзîâàíèå òåðмî-ýëåêòðèчåñêèõ èñòîчíèêîâ ïèòàíèÿ â мåдèцèí-ñêîé àïïàðàòóðå, îòñóòñòâóюò дàííыå îб èõ ïðè-мåíåíèè â ýëåêòðîííыõ мåдèцèíñêèõ òåðмîмå-òðàõ (ÝÌÒ). Зàмåíà õèмèчåñêèõ ýëåмåíòîâ ïè-òàíèÿ íà òåðмîýëåêòðèчåñêèå â òàêèõ òåðмîмå-òðàõ ðåшèëà бы ïðîбëåмó óòèëèзàцèè îòðàбî-òàííыõ õèмèчåñêèõ èñòîчíèêîâ ïèòàíèÿ, óëóч-шèâ òåм ñàмым ýêîëîãèчåñêîå ñîñòîÿíèå îêðó-жàющåé ñðåды. Имåííî ïîýòîмó â Иíñòèòóòå òåðмîýëåêòðèчåñòâà НАН è МОН Óêðàèíы àê-òèâíî ïðîâîдÿòñÿ ðàбîòы ïî ñîздàíèю òåðмî-ýëåêòðèчåñêèõ ïðåîбðàзîâàòåëåé дëÿ ïèòàíèÿ ЭМÒ [9][10][11][12]. Эффåêòèâíîñòь òåðмîýëåêòðèчåñêîãî ïðåîб-ðàзîâàòåëÿ зàâèñèò îò ñîãëàñîâàíèÿ åãî ñîïðî-òèâëåíèÿ, êîòîðîå îïðåдåëÿåòñÿ åãî êîíñòðóê-цèåé, è ñîïðîòèâëåíèÿ íàãðóзêè. В íàñòîÿщåé ðàбîòå ðåшàëàñь зàдàчà îïðåдåëåíèÿ òàêîé êîí-ñòðóêцèè òåðмîýëåêòðèчåñêîãî (ÒÝ) èñòîчíèêà ïèòàíèÿ ЭМÒ, êîòîðàÿ îбåñïåчèâàëà бы íåîбõî-дèмыå ýëåêòðèчåñêèå ïàðàмåòðы, à êîëèчåñòâî ÒЭ-мàòåðèàëà, íåîбõîдèмîãî дëÿ åãî èзãîòîâëå-íèÿ, быëî бы мèíèмàëьíым.Из òåõíèчåñêèõ õàðàêòåðèñòèê ЭМÒ èзâåñò-íî, чòî дëÿ åãî ýëåêòðèчåñêîãî ïèòàíèÿ íåîбõî-дèмî ïîñòîÿííîå íàïðÿжåíèå U = 1,5 В. В ðå-зóëьòàòå èзмåðåíèé быëî óñòàíîâëåíî, чòî ïðè òàêîм íàïðÿжåíèè мàêñèмàëьíыé òîê ñîñòàâëÿ-åò I max = 36 мêА, ò. å. мàêñèмàëьíàÿ ïîòðåбëÿå-мàÿ мîщíîñòь W max = 54 мêВò. Òàêèм îбðàзîм, ðàзðàбàòыâàåмыé èñòîчíèê ïèòàíèÿ дîëжåí îбå-ñïåчèâàòь óêàзàííыå ýëåêòðèчåñêèå ïàðàмåòðы.Äëÿ ðåшåíèÿ ïîñòàâëåííîé зàдàчè ïîñòðî-èм фèзèчåñêóю мîдåëь ÒЭ-èñòîчíèêà ïèòàíèÿ è ïðîâåдåм îцåíêó åãî ïàðàмåòðîâ дëÿ ðàзíыõ ðåжèмîâ ðàбîòы -мàêñèмàëьíîé мîщíîñòè è íåñîãëàñîâàííîé íàãðóзêè.Ìодель термоэлектрического источника питания Фèзèчåñêàÿ мîдåëь òåðмîýëåêòðèчåñêîãî èñ-òîчíèêà ïèòàíèÿ ЭМÒ ïðåдñòàâëåíà íà рис. 1. Òåïëîâîé ïîòîê Q 1 îò òåëà чåëîâåêà чåðåз ðà-дèàòîð 1 чàñòèчíî ïåðåдàåòñÿ òåðмîýëåêòðèчå-ñêîмó ïðåîбðàзîâàòåëю 2 (Q 2 ), чàñòèчíî ðàñ-ñåèâàåòñÿ â îêðóжàющóю ñðåдó (...

Electronic Medical Thermometer with Thermoelectric Power Supply

“…Such a thermometer comprises the electronic medical thermometer proper and the thermoelectric power supply. In turn, the electronic medical thermometer comprises a case (1), a temperature sensor (2), an analogto-digital converter (3), a voltage stabilizer (4), a capacitor (5) and a digital display (6). The thermoelectric power supply consists of two thermoelectric micromodules (7) and heat sink (8) that removes heat from the cold sides of thermoelectric micromodules (7) to the environment.…”

“…Preliminary estimates show that a thermoelectric converter of dimensions (5.7×5.7×5) mm 3 provides for the necessary parameters for the operation of the electronic thermometer. For this case one can use two thermoelectric converters of dimensions (4×4×5) mm 3 that can perfectly replace a conventional chemical galvanic cell in the electronic medical thermometer [6].…”

“…The thermophysical properties of human biological tissue are given in Table 1. The skin surface layer (epidermis (1)) of temperature Т 5 is in the state of heat exchange with heat-leveling plates (6) of high thermal conductivity material whose geometrical dimensions are a 6 , b 6 , l 6 . The contact surface temperature will be denoted by Т 6 .…”

“…Specific heat flux from the surface of temperature sensor (5) to the environment is q 5 , from the surface of heat sink (8) to the environment -q 7 , from free skin surface -q 8 , and specific heat flux of human internal organs -q 6 .…”

“…This problem is important, since thermometer readings determine immediate actions that should be taken. The foregoing implies that replacement of chemical galvanic cells and development of the thermoelectric power supply for the electronic thermometer owing to which the thermometer will be operated on human body heat is a problem of today [1][2][3][4][5][6][7][8][9][10][11][12][13]. However, no less important here is the accuracy of temperature measurement using the electronic medical thermometer with the thermoelectric power supply.…”