Ma'aunin zafi da sanyi na'ura ce da aka ƙera don auna zafin jiki . Akwai nau'ikan ma'aunin zafi da sanyi da yawa, amma duk suna aiki akan ƙa'ida ɗaya. Yawanci, muna amfani da kayan zafi da zafi, halayen da ke canzawa tare da zafin jiki. Idan zafin abu ya canza, siffarsa da girmansa suma suna canzawa. Yawancin ma'aunin zafi da sanyi suna amfani da kayan da ke faɗaɗa ko raguwa tare da canje-canje a zafin jiki.
Na'urar tantancewa wanda ake amfani da shi a yau ya ƙunshi bututun gilashi, wanda a ciki akwai barasa ko 
Mercury a tsakiyar bututun. Lokacin da zafin jiki Yayin da zafin jiki ke ƙaruwa, barasa ko mercury a cikin akwati yana faɗaɗa, yana ƙara tsawon ginshiƙin barasa ko mercury. Akasin haka, yayin da zafin jiki ke raguwa, tsawon ginshiƙin barasa ko mercury yana raguwa. A wajen bututun gilashi akwai lambobi waɗanda ke wakiltar ma'aunin ma'aunin zafi. Lambar da saman ginshiƙin barasa ko mercury ya nuna tana nuna zafin abin da ake aunawa.
Wani nau'in ma'aunin zafi da sanyi da ake amfani da shi akai-akai shine wanda ke amfani da tsiri na bimetallic (ƙarfe biyu daban-daban tare da saurin faɗaɗawa daban-daban). Yayin da zafin jiki ke ƙaruwa, ƙarfe ɗaya yana faɗaɗa fiye da ɗayan, wanda ke sa tsiri ya lanƙwasa. Yawanci, tsiri na bimetallic yana da siffar karkace, tare da gyara ƙarshen ɗaya ɗayan kuma an haɗa shi da ma'aunin zafi da sanyi. Yayin da zafin jiki ke canzawa, ma'aunin zafi da sanyi yana juyawa. Ana amfani da ma'aunin zafi da sanyi da ke amfani da tsiri na bimetallic azaman ma'aunin zafi na iska na yau da kullun, ma'aunin zafi da sanyi na ɗaki, ma'aunin zafi da sanyi na tanda, da sauransu.
Ma'aunin zafi mafi daidaito, ko mafi daidaito, yawanci yana amfani da halayen lantarki na wani abu. Misali, ma'aunin zafi mai juriya yana auna canjin juriyar lantarki na siraran waya ko silinda na carbon ko germanium crystal. Saboda yawanci ana iya auna juriyar lantarki daidai, ma'aunin zafi mai juriya na iya auna zafin jiki daidai fiye da ma'aunin zafi na yau da kullun.
