• The beekeeper charges the battery of the device.
• The beekeeper gets fresh, cooled sensorelectrodes. He can store them in the fridge.
• The beekeeper takes 10 bees from a hive and washes them in 100ml water in a special cup or takes honey and dilutes it
in the same amount of water.
• Maybe the water has to be heated up to 85°C. This is to transform the spores of Paenibacillus larvae to their vegetative form.
• The beekeeper drops a drop of the water into a sensorelectrode.
• The beekeeper waits until the sensorelectrode is dry.
• The beekeeper connects the sensorelectrode to the diagnosis-device.
• The beekeeper drops a few drops of Kaliumhexocyanoferrat onto the sensorelectrode
• The beekeeper starts the measurement with a button on the diagnosis-device.
• The beekeeper waits for the measurement to be complete (less than 1 minute)
• With a display and several LEDs, the result is displayed by the diagnosis-device.
• (The beekeeper can look up recommended action steps for the degree of infestation at hand on a smartphone app.)
• The beekeeper disconnects the sensorelectrode, and stores it until he gets sensorelectrodes next time. He will get a discount, and we can recycle the electrodes.
Internal requirements
All requirements that come from our own understanding of the problems. They are based upon the basic literature we used and contain our own accumulated wisdom. They should be the blueprint for engineers in the final development process for engineers.
REQ_0001
A diagnosis system for the American foulbrood (AFB) should be developed. The System can be divided into the following parts: sensorelectrode, diagnosis-device, smartphone app, equipment
REQ_0002
The system should allow beekeepers to conduct a precise, fast and easy diagnosis on site.
REQ_0003
A part of the system should allow the beekeeper to savely wash exactly 10 bees in exactly 100ml water.
REQ_0004
A part of the system should allow the beekeeper to measure the concentration of AFB spores within a drop of water. Other factors like temperature, light, water hardness, slight pollution with honey or pollen should not affect the measurement results!
REQ_0005
A part of the system should display the severity of infestation with the colors red, green and yellow.
REQ_0006
A part of the system should allow the beekeeper to look up concrete action steps for the severity of infestation at hand.
OPT_0007
A part of the system should automatically upload the measurement results to an online database, if and only if the beekeeper agreed to this.
OPT_0008
A part of the system should allow the beekeeper to look at a map, where the regions with high uploaded measurement results are highlighted.
REQ_0101
Software code has to be commented adequately.
External requirements
Additional requirements which are based upon market research. These contain very valuable insights of the preferences of the beekeepers. Their implementation is crucial for the market success of the device. They have been determined by the survey, see human practices
REQ_EXT_001
A device for the detection of AFB should be built that is more accurate that the current laboratory test method. Furthermore the device has to be easy to use and withstand an usability test.
REQ_EXT_002
The measurement results should be displayed on a display directly on the device.
REQ_EXT_003
The user should be able to connect the device to an android smartphone. The device should be able to display results and be controlled via the smartphone.
REQ_EXT_004
The device should display the severity of infestation also by color coded LEDs (red, yellow, green).
REQ_EXT_005
The device should display the concentration of spores on a display, the severity of infestation by color coded LEDs.
REQ_EXT_006
There should be detailed explanation regarding the measurement results including recommended activities available in the smartphone app.
REQ_EXT_007
There should be a video tutorial available online.
REQ_EXT_008
There should be a manual within the smartphone app.
REQ_EXT_009
The device should be able to measure honey dome samples (maybe dissolved in water).
REQ_EXT_010
The price of the device should not exceed 75€.
REQ_EXT_011
The smartphone-app should give the user the possibility to enter his geographic information.
REQ_EXT_012
The smartphone-app should (if permitted by the user) automatically upload the measurements with geographic information.
1 Sensorelectrode
Figure 1: Desired electrical behavior of the sensorelectrode (Han 2016)
REQ_1001
A process for making sensorelectrodes should be developed.
REQ_1002
The sensorelectrode should have three electrical connectors:
· Working Electorode (WE)
· Counter Electrode (CE)
· Reference Electrode (RE)
REQ_1003
The sensorelectrode should allow the user to drop a drop of water onto it and let it dry.
REQ_1004
Die sensorelectrode should work with Kaliumhexocyanoferrat as a redox-couple-solution.
REQ_1005
The electron transfer resistance or charge transfer resistanc Ret should increase logarithmically with the increase of the concentration of the spores of Paenibacillus larvae.
REQ_1006
The electron transfer resistance should not be influenced by other stuff that is typically present on bees or in the beehive.
If there IS influence, it has to be somehow compensated!
REQ_1007
The sensorelectrode should be durable for at least 4 weeks in the fridge.
REQ_1008
The Ret should maximally change by 10 ohms per 24 hours.
2 Diagnosis-Device
Figure 2: Measurement circuit
Figure 3: Electrical description EIS with 3 electrodes (A Carullo 2000)
Figure 4: Draft of diagnosis device
REQ_2001
A device for the measurement of the difference of the charge transfer resistance of a sensorelectrode with electrochemical impedance spectroscopy (EIS) should be developed (resistance with bounded spores vs resistance without them).
REQ_2002
The device should be able to measure impedances between 1kΩ and 10kΩ in the frequency range btween 0,1Hz and 100kHz. (Han 2016)
REQ_2003
The impedance measurement should be carried out with an AC voltage of 5mV peak-to-peak.
REQ_2004
The measurement should be done via three electrodes:
· Working Electorode (WE)
· Counter Electrode (CE)
· Reference Electrode (RE)
REQ_2005
The voltage of the RE can be regulated to a constant operating point (XXV - XXV). The control can be very slow (time constant: 1s)
REQ_2006
The device should have a battery, which can be charged with a USB cable.
REQ_2007
The device should give the user the opportunity to connect it via Bluetooth to a smartphone.
OPT_2008
The optimal operating point of the RE should be determined by a cyclic voltametry measurement before the EIS measurement. The operating point should be adjusted to the middle of the two maxima of the curve (see fig. 5)
OPT_2009
The device should measure the temperature of the sensorelectrode and compensate for the temperature induced measurement offset.
3 Equipment
List of necessary equipment:
• Charging cable
• Cups for gentle catching and washing of the bees
• Pipettes for applying wash water to the sensorelectrodes
• Online manual as text & video
• Kaliumhexocyanoferrat
4 Open questions
question
how to answer
Do the phages (HB10c2also bind to the spoes of Paenibacillus larvae or only to the vegetative form?
Lab-tests
Does there have to be a reference measurement without spores?
Lab-tests, Research of methods
How long are the sensorelectrodes durable/stable? How can the durability be improved?
Lab-tests
Can we also use honey comb samples instead of washing bees?
