Implantable power sources and sensors

Abstract

A protein is provided, including a glucose binding site, cyan fluorescent protein (CFP), and yellow fluorescent protein (YFP). The protein is configured such that binding of glucose to the glucose binding site causes a reduction in a distance between the CFP and the YFP. Substance monitoring apparatus ( 210 ) is also provided, including a semi-permeable barrier ( 212 ), adapted to be implanted in a body of a subject and to allow passage therethrough of a substance, while inhibiting passage therethrough of immune cells; and microorganisms ( 214 ), disposed within the semi-permeable barrier ( 212 ) so as to produce a measurable response to a level of the substance. A sensor ( 220 ) is adapted to measure the measurable response and not to measure a response of any mammalian cells that may be disposed within the semi-permeable barrier ( 212 ).

1 - 3 . (canceled) 
     
     
         4 . Apparatus comprising a biofuel cell, adapted to be implanted in a body of a subject in fluid communication with blood of the subject, the biofuel cell comprising:
 an electrolyte membrane;   an anode, coupled to the membrane;   photosynthetic cells that photosynthetically generate oxygen using water present in the blood;   a light source, adapted to illuminate the photosynthetic cells; and   an oxygen cathode, coupled to the membrane, and adapted to use the oxygen as a reagent.   
     
     
         5 . The apparatus according to  claim 4 , wherein the photosynthetic cells comprise algae. 
     
     
         6 . The apparatus according to  claim 4 , wherein the photosynthetic cells are loaded into the oxygen cathode. 
     
     
         7 . The apparatus according to  claim 4 , wherein the apparatus is adapted to power the light source using a portion of energy generated by the biofuel cell. 
     
     
         8 . The apparatus according to  claim 4 , wherein the anode is adapted to use a substance in the blood as a reagent, and wherein the apparatus is adapted to determine a concentration of the substance in the blood responsively to a level of power output by the biofuel cell. 
     
     
         9 . The apparatus according to  claim 4 , comprising fuel-generating cells that biosynthetically generate a fuel, using a constituent of the blood as an input, wherein the anode is adapted to use the fuel as a reagent. 
     
     
         10 . Apparatus comprising a biofuel cell, adapted to be implanted in a body of a subject in fluid communication with blood of the subject, the biofuel cell comprising:
 an electrolyte membrane;   a cathode, coupled to the membrane;   cells that biosynthetically generate a fuel, using a constituent of the blood as an input; and   an anode, coupled to the membrane, and adapted to use the fuel as a reagent.   
     
     
         11 . The apparatus according to  claim 10 , wherein the cells comprise algae. 
     
     
         12 . The apparatus according to  claim 10 , wherein the cells are loaded into the anode. 
     
     
         13 . The apparatus according to  claim 10 , wherein the fuel includes ethanol, and the cells generate the ethanol. 
     
     
         14 . The apparatus according to  claim 10 , wherein the constituent includes glucose, and wherein the cells generate the fuel using the glucose as the input. 
     
     
         15 . The apparatus according to  claim 10 , wherein the apparatus is adapted to determine a concentration of the constituent in the blood responsively to a level of power output by the biofuel cell. 
     
     
         16 - 41 . (canceled)