WHOLE in ONE Temperature Probe

Unique measuring appliance for determining temperature profiles in solid structures

One borehole for four temperature measurement layers, plus measurement of the air temperature in one probe - a convenient time saving approach for your measuring demand.

Ever dreamed of a simple solution, measuring and displaying temperature profiles in solids like:

The printed circuit board PCB based  probe is impregnated to withstand humid environment. It is quickly inserted and comes with pre-localized sensors via XML, so the temperature gradient may be calculated quickly.

Questions and answers

Question: So if you have only one borehole, how significant are the measured values for the actual position?

Answer: The printed circuit has lower heat conduction than brick or concrete walls [source], and the PCB cross-sectional area is only 6mm x 2mm=12mm of the total 28m². The cavities are covered via insulating strip, so longitudinal air circulation is strongly reduced. The sensors are also in direct radiative contact to the wall, since there is no surrounding hull, which might induce heat flow from other layers.

Question: How many measurements are possible per period of time?

Answer: The conversion of the temperature needs 100ns to 750ms 9 bit/12 bit, according to the specification. Those conversions however are made in parallel in the digital sensors. Typical construction structures have quite high heat inertia, so this is absolutely no limitation.

Question: What is the heat release of the digital sensor?

Answer: The input current of one DS18B20 is only 5µA, so there is very low heat dissipation.

Question: Is the reading of the 1-wire bus data complicated?

Answer: Raspberry Pi's have embedded support for 1-wire. You may also employ USB-connected converters, so all platforms are supported.

What accuracy is to be expected: The main difference to resistive temperature sensors is that the digital sensor is embedded in a polymer with a conductivity of 383 W/mK [source]. The drift is +/- 0.2 K per 1000 hrs. No errors are induced after digitalization in the DS18B20 temperature sensor.

prototype long pcb based temperature probe total
prototype long pcb based temperature probe half inserted
prototype long pcb based temperature probe nearly inserted
prototype long pcb based temperature probe inserted
prototype long pcb based temperature probe after pulling out

What is the price?

Some prototypes were produced (shown above) and it is now time to ask the potential customers to reserve their probe, so a larger quantity may be produced . The amount of probes per PCB board is 4 and depending on the number of PCB boards the price might  be falling down to 10€ per board. Additionally the DS8020 amounts to 1.5€ per piece, so material cost may be as low as 20€ per probe, adding labor to solder the temperature sensors and to add thermal insulation between measuring locations. Larger quantities might be made in low wage countries, keeping total cost low. Of course some overhead and the development cost will be added, but the target price for larger quantities will stay below 50€.

Connectivity/data storage

Data upload may be done via Python on a Raspberry Pi zero or even less powerful boards, however HTTPs shall be usable. No additional cost is resulting from the use of the visualization  solution if you opt for storing data on our server opting for an all-in solution. To store larger quantities of sensor data, your own data server or a separate installation (database table) shall be set up. Please ask for an offer at office@effiziente.st.

prototype long pcb based temperature probe dashboard python

Survey about your demand

Please list yourself as potential client, so we may plan the ramp up of the production.