Sensor apparatus and sensor system

Abstract

To provide a sensor apparatus and sensor system using a low-power input source such as a microbial fuel cell, provided is a sensor apparatus including a microbial fuel cell; a boosting DC-DC circuit that operates based on an input voltage from the microbial fuel cell and boosts the input voltage; a power storage element that stores power output from the boosting DC-DC circuit; and a sensor element that operates based on power output from the power storage element, as well as a sensor system that includes this sensor apparatus and a wireless communication apparatus.

What is claimed is: 
     
         1 . A sensor apparatus comprising:
 a microbial fuel cell;   a boosting DC-DC circuit that is operated by an input voltage from the microbial fuel cell and boosts the input voltage;   a power storage element that stores power output from the boosting DC-DC circuit; and   a sensor element that is operated by power output from the power storage element.   
     
     
         2 . The sensor apparatus according to  claim 1 , comprising:
 a first hysteretic comparator that detects an output voltage from the power storage element, to control operation of the boosting DC-DC circuit.   
     
     
         3 . The sensor apparatus according to  claim 2 , wherein
 when the first hysteretic comparator detects that the output voltage has become greater than or equal to a first threshold value, operation of the boosting DC-DC circuit is stopped, and later, when the first hysteretic comparator detects that the output voltage has become less than or equal to a second threshold value, operation of the boosting DC-DC circuit is started.   
     
     
         4 . The sensor apparatus according to  claim 1 , comprising:
 a second hysteretic comparator that detects the output voltage from the power storage element to control operation of a switch that is connected between the power storage element and an output terminal of the boosting DC-DC circuit.   
     
     
         5 . The sensor apparatus according to  claim 4 , wherein
 when the second hysteretic comparator detects that the output voltage has become greater than or equal to a third threshold value, the switch is turned ON and output of the output voltage is started, and later, when the second hysteretic comparator detects that the output voltage has become less than or equal to a fourth threshold value, the switch is turned OFF and the output of the output voltage is stopped.   
     
     
         6 . The sensor apparatus according to  claim 1 , wherein
 the microbial fuel cell has a long and thin stake shape, with an anode electrode for installation in an anaerobic environment attached to one end side thereof, and   the stake shape is any one of a tube shape, a circular pillar shape, a cone shape, a polygonal pillar shape, and a polygonal cone shape.   
     
     
         7 . The sensor apparatus according to  claim 6 , wherein
 a cathode electrode for contacting air, and having a flat surface portion orthogonal to a longitudinal direction of the stake shape, is attached to the other end side of the stake shape, and   the cathode electrode includes carbon fiber and stainless mesh sandwiching the carbon fiber.   
     
     
         8 . The sensor apparatus according to  claim 7 , wherein
 the microbial fuel cell further includes a rod-shaped member provided between the anode electrode and the cathode electrode, and a connecting portion that connects the rod-shaped member to the anode electrode and the cathode electrode, and   the rod-shaped member is a polyvinyl chloride pipe or wood.   
     
     
         9 . The sensor apparatus according to  claim 1 , wherein
 the sensor element is an environmental sensor that senses environmental information.   
     
     
         10 . The sensor apparatus according to  claim 9 , wherein
 the environmental sensor senses at least one of temperature, humidity, ultraviolet light amount, visible light amount, carbon dioxide concentration, air pressure, sound pressure, and acceleration.   
     
     
         11 . The sensor apparatus according to  claim 1 , further comprising:
 a display section that displays at least one of an operational state of the sensor element and a state of charge of the power storage element.   
     
     
         12 . The sensor apparatus according to  claim 1 , further comprising:
 an auxiliary power supply that supplies power at least to the sensor element.   
     
     
         13 . The sensor apparatus according to  claim 1 , further comprising:
 a wireless circuit that transmits a sensing result of the sensor element.   
     
     
         14 . The sensor apparatus according to  claim 13 , further comprising:
 an MCU that controls operation of the wireless circuit.   
     
     
         15 . A sensor system comprising:
 one or more sensor apparatuses, each sensor apparatus being the sensor apparatus according to  claim 13 , and   a wireless communication apparatus that receives the sensing result of the sensor element from the sensor apparatus via wireless communication, and transmits the sensing result to a communication network.   
     
     
         16 . A sensor system comprising:
 an energy harvesting power supply;   a power storage element that stores power output from the energy harvesting power supply;   a first wireless circuit that wirelessly transmits a signal, according to power output from the power storage element;   a second wireless circuit that receives the signal transmitted from the first wireless circuit; and   a determining section that determines a state of the energy harvesting power supply, based on the signal received by the second wireless circuit.   
     
     
         17 . The sensor system according to  claim 16 , further comprising:
 a boosting circuit that is operated by an input voltage from the energy harvesting power supply and boosts the input voltage, wherein   the power storage element stores power output from the boosting circuit.   
     
     
         18 . The sensor system according to  claim 16 , wherein
 the energy harvesting power supply uses light energy as an energy source.   
     
     
         19 . The sensor system according to  claim 18 , wherein
 the light energy is light energy of at least one of sunlight, an incandescent lamp, a fluorescent lamp, and an LED.   
     
     
         20 . The sensor system according to  claim 16 , wherein
 the energy harvesting power supply uses thermal energy as an energy source.   
     
     
         21 . The sensor system according to  claim 20 , wherein
 the thermal energy is thermal energy of at least one of heat generated by a machine and environmental temperature.   
     
     
         22 . The sensor system according to  claim 16 , wherein
 the energy harvesting power supply uses vibration as an energy source.   
     
     
         23 . The sensor system according to  claim 22 , wherein
 the vibration is at least one of vibration generated by a machine, vibration of a bridge, vibration of a road, vibration of a building, vibration of a house, vibration of a rail, vibration of a human, vibration of an animal, vibration of a ball screw, and vibration of a linear guide.   
     
     
         24 . The sensor system according to  claim 16 , wherein
 the energy harvesting power supply uses electromagnetic waves as an energy source.   
     
     
         25 . The sensor system according to  claim 16 , herein
 the energy harvesting power supply is a microbial fuel cell.   
     
     
         26 . The sensor system according to  claim 16 , wherein
 the determining section determines the state based on any one of how frequently the signal is received, strength of the signal, an interval between signals, and frequency of the signal.   
     
     
         27 . The sensor system according to  claim 26 , wherein
 the determining section determines the state to be a first state if any one of how frequently the signal is received, the strength of the signal, the interval between signals, and the frequency of the signal is greater than or equal to a predetermined threshold value, and determines the state to be a second state if the same one of how frequently the signal is received, the strength of the signal, the interval between signals, and the frequency of the signal is less than the predetermined threshold value.   
     
     
         28 . The sensor system according to  claim 27 , wherein
 the first state is a state in which the energy harvesting power supply is healthy, and   the second state is a state in which the energy harvesting power supply is not healthy.