TMP117 section 5cm

DxP Sensor Probe PCB Designs

This repository contains the PCB designs for DxP (Distributed sensor Profiling) sensor probes—including sensor sections and the connector/extension pieces needed to assemble probe chains.

Not included: the data logger hardware (it lives in the separate DxP data logger repository).
Not included: the mechanical probe tube/epoxy assembly instructions. This repo focuses on the PCB designs only.

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Technology overview

The sensor probe concept is based on cascaded I²C sensor arrays using a solderless board-to-board connector to build probes of configurable length. Each probe section maintains the required sensor spacing and enables deformation (ADXL345) and/or temperature (TMP117) profiling.

Reference (sensor probes):
Wielandt et al., “Low-Power, Flexible Sensor Arrays with Solderless Board-to-Board Connectors for Monitoring Soil Deformation and Temperature” (Sensors, 2022) DOI: 10.3390/s22072814

Use with the DxP data logger

Sensor probes in this repository connect to the DxP data logger (separate repo), which performs wireless data logging and connectivity for distributed deployments.
Reference (data logger / network):
Wielandt et al., “TDD LoRa and Delta Encoding in Low-Power Networks of Environmental Sensor Arrays for Temperature and Deformation Monitoring” (J. Signal Process. Syst., 2023) DOI: 10.1007/s11265-023-01834-2

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Critical manufacturing note

• PCB thickness requirement: all boards in this repo must be manufactured with 0.6 mm FR4 thickness.
  • This is required for the press-fit solderless interconnection to work reliably.

Solderless interconnection method

Adjacent probe boards are connected using a mechanical + electrical snap-fit made entirely in PCB technology:

• Each section uses complementary male/female connector features on the board edges.
• When pressed together, metal-plated mating areas create reliable electrical contact.
• The connector design remains mechanically stable over probe bending and long-term field conditions.

(For clarity: the extension/adapter connector combinations in this repo are engineering building blocks; the connector technology used between standard sensor sections is described in the Sensors 2022 paper and U.S. Patent US 11,582,870 B2.)

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What each PCB design directory is for

End connectors (probe-to-logger interface)

• end_connector/

  • Provides the probe end used to connect the assembled sensor chain to the DxP data logger side.
  • Interfaces via a cable connector type SM06B-SRSS-TB (probe cable side).
  • Most-used end connector design (over 1,000 pcs used to date).
  • In typical deployments it is the data logger side end of the probe assembly (some foldable configurations use end connectors at both ends).

• off-axis_end_connector/

  • Off-axis variant for different mechanical assemblies.
  • Validated in prototypes, but used at scale less frequently so far.
  • Intended to simplify assembly alignment in alternative probe/logger geometries.

Sensor sections

• TMP117_section_5cm/

  • Contains 4× TMP117 temperature sensors.
  • Sensors are spaced at 5 cm, and this 5 cm spacing is maintained between sections when the probe is assembled.

• TMP117_section_10cm/

  • Functionally the “same” PCB platform as the 5 cm section, but designed for 10 cm spacing.
  • Achieved by leaving half the TMP117 locations unpopulated, resulting in cheaper assemblies for longer spacing requirements.

• TMP117-ADXL345_section_5cm/

  • Alternates TMP117 and ADXL345 locations on the same overall section footprint.
  • When sections are cascaded and rotated during assembly, this yields the 90°/spiral arrangement used in the Sensors 2022 deformation measurement approach.

Probe length extension / flexible assembly adapters

These boards extend probe length without adding sensors (and support mixed rigid/flexible assembly concepts). These connector pieces and combinations were not published in literature.

• extension_board_MF/

  • Sensorless extension board adding ~200 mm probe length.
  • Contains connector ends male/female.

• extension_board_MM/

  • Sensorless extension board adding ~300 mm probe length.
  • Contains connector ends male/male.

• FF_connector/

  • Short female–female adapter piece used for assembling compatible chains/extensions.

Board outline (mechanical layout aid)

• sensor_board_outline/
  • Provides the board and connector outline for a probe section without sensors, including copper patterns needed for the end connections.
  • Intended for mechanical/CAD/layout reference and section-template usage.

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Repository contents (files per PCB)

Each PCB design directory typically contains:

• KiCad schematic / PCB:
  • *.sch, *.kicad_pcb, plus associated project files (*.kicad_pro, *.kicad_prl)
• KiCad BOM/export:
  • *_BOM.csv-style files where applicable (e.g., in end_connector/fab/)
• Fabrication / export outputs:
  • fab/ (per-project fabrication exports)
• Shared KiCad library helpers:
  • fp-lib-table, sym-lib-table, and fp-info-cache/
• Documentation:
  • README.md, LICENSE.mdand users.md (self-reported user tracking)

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User tracking

• users.md: self-reported adopters/projects using the DxP probe hardware (recommended).

If you want, I can also tighten this further to match the logger README format even more closely (shorter “Hardware overview” + “Repository contents” only), but the text above should already be accurate and concise for a probe-repo release.