---
lang: en-CA
documentclass: article
papersize: letter
fontsize: 9.5pt
geometry: margin=0.70in,headheight=18pt,headsep=16pt,footskip=25pt
mainfont: "DejaVu Serif"
sansfont: "DejaVu Sans"
monofont: "DejaVu Sans Mono"
colorlinks: true
linkcolor: NanoNavy
urlcolor: NanoBlue
toc: false
toc-depth: 2
header-includes:
  - |
    \usepackage{xcolor,colortbl,fancyhdr,titlesec,booktabs,longtable,array,enumitem,microtype}
    \definecolor{NanoNavy}{HTML}{24364B}
    \definecolor{NanoBlue}{HTML}{496B86}
    \definecolor{NanoPale}{HTML}{E8EEF3}
    \definecolor{NanoRule}{HTML}{9AAABA}
    \pagestyle{fancy}\fancyhf{}
    \fancyhead[L]{\small\sffamily\color{NanoNavy} NANOARC $\mid$ Hydrogel Carrier Screen}
    \fancyhead[R]{\small\sffamily\color{NanoBlue} Rev0}
    \fancyfoot[C]{\small\color{NanoNavy}\thepage}
    \renewcommand{\headrulewidth}{0.4pt}
    \titleformat{\section}{\Large\bfseries\sffamily\color{NanoNavy}}{\thesection.}{0.55em}{}
    \titleformat{\subsection}{\large\bfseries\sffamily\color{NanoBlue}}{\thesubsection}{0.55em}{}
    \titleformat{\subsubsection}{\normalsize\bfseries\sffamily\color{NanoNavy}}{\thesubsubsection}{0.55em}{}
    \renewcommand{\arraystretch}{1.18}
    \setlength{\parindent}{0pt}\setlength{\parskip}{4pt}
    \setlist{nosep,leftmargin=1.45em}
    \hypersetup{pdftitle={NanoArc Hydrogel Electrolyte Carrier Screen Rev0},pdfauthor={NanoArc experimental chemistry},pdfsubject={Calcium alginate and agar electrolyte-carrier coupon screening}}
---

\begin{titlepage}
\thispagestyle{fancy}
\vspace*{0.70in}
\begin{center}
{\Huge\bfseries\sffamily\color{NanoNavy} NanoArc Hydrogel\\Electrolyte-Carrier Screen}

\vspace{0.25in}
{\Large\color{NanoBlue} Calcium Alginate and Agar Coupon Programme}
\end{center}
\vspace{0.42in}
\rowcolors{1}{NanoPale}{white}
\begin{tabular}{>{\bfseries}p{1.25in}p{4.50in}}
Programme & HYDROGEL-CARRIER-001 \\
Status & Approved plan; materials not procured or tested \\
Revision & Rev0 \\
Date & 2026-08-13 \\
Budget & CA\$60 before shipping, excluding owned reusable tools \\
Authority & Tristan retains experiment, safety, and disposition authority \\
RevA impact & None \\
\end{tabular}
\rowcolors{1}{}{}
\par
\vspace{0.36in}

{\large\bfseries\color{NanoNavy} Purpose.} Compare calcium alginate and ordinary agar as passive carriers for a benign conductive liquid. The programme measures repeatability, impedance, leakage, drying, compression recovery, and handling before any plating chemistry or pen hardware is introduced.

\vfill
\fcolorbox{NanoRule}{NanoPale}{\parbox{0.91\textwidth}{\textbf{Boundary.} This is a low-energy material screen, not electroplating. No DC source, metal-bearing electrolyte, plating coupon, ACE connection, or NanoArc hardware is permitted. Food-grade sourcing does not make laboratory specimens edible.}}
\end{titlepage}

\tableofcontents
\clearpage

# Objective and decision

The screen answers one question: which gel can repeatedly hold and conduct a
standard saline solution while remaining mechanically usable as a future wet
contact? It does not attempt to optimize a pen tip or predict performance with
metal ions.

The two routes share specimen geometry, saline concentration, equilibration,
electrodes, compression, measurement settings, and acceptance gates. Recipe
changes during the campaign are prohibited. If both routes fail, the result is a
valid baseline for a later concentration screen.

## Decision rule

A route must pass every hard gate before electrical ranking. Among passing
routes, the lower stable median 1 kHz impedance wins. Lower drying drift breaks
a tie. A visually attractive gel cannot win by bypassing repeatability,
containment, or handling requirements.

## Programme boundaries

- Coupon materials only; no mock pen or reservoir.
- No copper, nickel, zinc, citrate, sulfate, plating salt, or unknown additive.
- No DC resistance measurement, bench supply, electrolysis, or current forcing.
- No claim of plating compatibility or service life.
- No ACE, Dreadnaught, Service Key, firmware, connector, or shared-interface
  change.
- All containers, tools, and specimens become laboratory-only.

# Procurement and identification

## Material baseline

| Code | Material | Required identity | Initial amount |
|---|---|---|---:|
| ALG | Sodium alginate | Single ingredient, food or reagent grade; supplier and lot recorded | 100 g or smallest economical pack |
| CA | Calcium chloride dihydrate | CAS `10035-04-8`; documented hydrate and grade | 100 g or smallest economical pack |
| AGR | Agar powder | Single ingredient, food grade; not a prepared dessert mix | 100 g |
| NACL | Sodium chloride | Pure non-iodized reagent or pickling salt; no anti-caking additive if practical | 100 g minimum |
| WATER | Distilled water | Sealed retail or laboratory container; lot/source recorded | 2 L |

The basket must remain at or below CA$60 before shipping. Do not substitute
agarose, premium bacteriological agar, calcium lactate, table salt with unknown
additives, or an undocumented calcium-chloride hydrate merely to complete the
order. If compliant materials exceed the cap, stop and return the basket to
Tristan for sourcing review.

## Incoming record

For each material, record the supplier, product name, package size, price,
shipping allocation, ingredient statement, CAS number where provided, grade,
hydrate state, lot, received date, storage condition, SDS location, and package
photograph. Reject damaged, wet, unlabelled, or compositionally ambiguous stock.

## Reusable apparatus

- 0.01 g scale;
- distilled-water-compatible glassware and dedicated utensils;
- hotplate and temperature probe for agar preparation;
- PETG coupon mould, nominal 20 mm diameter by 3 mm deep;
- vernier caliper or equivalent dimensional tool;
- fixed-stop impedance/compression fixture;
- two identical flat stainless-steel electrodes with 20 mm active diameter;
- FNIRSI LC1020E and its Kelvin leads;
- documented 100 g test mass;
- absorbent test papers and sealable labelled containers;
- camera or webcam, timer, gloves, and splash eye protection.

Above-bath printed parts are PETG. PLA or PLA+ may serve as dry templates only.
Measure and record the actual mould and fixture dimensions before use.

\clearpage

# Standard solutions and specimens

## Common 0.100 M NaCl solution

1. Tare a clean container and weigh `2.922 g` sodium chloride.
2. Dissolve in approximately 400 mL distilled water.
3. Transfer quantitatively to a graduated vessel and bring the final volume to
   `500.0 mL` with distilled water.
4. Mix until clear, label `NACL-0.100M`, and record preparation time,
   temperature, material lot, actual mass, and final volume.

The 0.01 g scale supports this screening solution. Do not energize the solution
with DC. Sodium chloride is selected only to avoid calcium-sulfate precipitation
and citrate-driven calcium removal during this benign carrier comparison.

## Calcium-alginate route

1. Weigh `2.00 g` sodium alginate and prepare `100.0 mL` total mixture with
   distilled water for a nominal `2.00% w/v` alginate solution.
2. Add powder gradually with mixing. Cover and allow bubbles and dry agglomerates
   to clear; record the actual rest time.
3. Weigh `2.00 g` calcium chloride dihydrate and prepare `100.0 mL` total
   cross-link bath with distilled water for nominal `2.00% w/v`.
4. Fill four measured mould cavities without entrained dry pockets.
5. Cross-link each specimen completely in the calcium bath for 60 minutes,
   turning once at 30 minutes without squeezing it.
6. Rinse each specimen twice for 30 seconds in separate distilled-water portions.
7. Assign `ALG-2-R1`, `ALG-2-R2`, `ALG-2-R3`, and destructive witness
   `ALG-2-W`.

Cut `ALG-2-W` through its centre after cross-linking. A liquid or paste-like core
fails the batch. Do not extend only the measured specimens' treatment after
seeing the witness; repeat the complete batch under a new campaign suffix.

## Agar route

1. Weigh `2.00 g` agar and prepare `100.0 mL` total mixture with distilled water
   for nominal `2.00% w/v`.
2. Heat with stirring until the agar is fully dispersed and the mixture is
   uniformly clear or consistently translucent. Record peak temperature and
   time; do not permit boil-dry.
3. Cool while covered to `55-60 C`, then fill four measured mould cavities.
4. Allow to gel undisturbed for 60 minutes at recorded room temperature.
5. Assign `AGR-2-R1`, `AGR-2-R2`, `AGR-2-R3`, and destructive witness
   `AGR-2-W`.

Cut `AGR-2-W` through its centre. A liquid core, dry powder pocket, or grossly
nonuniform structure fails the batch.

## Saline equilibration

Place the three intact specimens from each route in separate labelled covered
baths of `NACL-0.100M` for `24.0 hours` at room temperature. Use at least 10 mL
solution per specimen. Never share equilibration liquid between routes. Record
pre-soak and post-soak mass and dimensions.

# Fixture and instrument controls

## Fixed geometry

The fixture presents two clean, parallel stainless-steel electrodes to the flat
faces of a 20 mm coupon. A mechanical stop fixes the electrode separation at the
recorded specimen thickness; it must not depend on operator grip. The fixture
shall also provide a second stop at `80%` of the specimen's initial thickness for
compression cycling.

Before wet work, photograph the fixture and record electrode material, active
diameter, separation, surface condition, cleaning method, lead attachment, and
stop dimensions. Inspect for sharp edges that could cut a gel.

## LC1020E configuration

1. Warm the instrument for 30 minutes.
2. Fit the same leads and fixture used for all specimens.
3. Perform open and short calibration at each selected frequency.
4. Select `Z` as the primary parameter, `0.1 V RMS`, and `0.0 V` internal bias.
5. Measure at `100 Hz`, `1 kHz`, and `10 kHz`.
6. Record impedance magnitude and phase angle. The primary endpoint is 1 kHz.
7. Take five readings after the display stabilizes; do not cherry-pick readings.

Validate the assembled fixture using one documented resistor within the
LC1020E's range before and after the wet session. A reference drift greater than
2% invalidates the session pending fixture inspection and recalibration.

Do not use the DMM resistance mode on the gel. DC polarization and electrode
reactions would make the comparison time-dependent and would violate the
non-electrolysis boundary.

\clearpage

# Test sequence

Run all three alginate and all three agar replicates through the same sequence.
Alternate route order between specimens so elapsed time does not systematically
favour one material.

## Stage A - incoming condition

- Blot each specimen with one identical, documented contact procedure; do not
  squeeze it.
- Record mass, diameter at two axes, thickness at three positions, appearance,
  surface liquid, tears, bubbles, and photographs.
- Record room temperature and relative humidity if available.

## Stage B - initial impedance

- Install the specimen at the uncompressed fixed stop.
- Record five stable readings at 100 Hz, 1 kHz, and 10 kHz.
- Remove it and inspect the electrodes and specimen for residue or damage.
- Rinse and dry electrode surfaces identically before the next specimen.

## Stage C - handling

Perform ten complete installation/removal cycles. A cycle includes alignment,
closure to the uncompressed stop, reopening, and removal by hand without tools.
Record fracture, permanent deformation, sticking, residue, or loss of a usable
flat contact surface.

## Stage D - compression

Perform ten cycles from the uncompressed stop to `80%` initial thickness, hold
for five seconds, and release. Do not exceed the stop. After five minutes of
recovery, measure thickness at the same three positions and repeat the 1 kHz
impedance measurement.

## Stage E - controlled leakage

1. Weigh a clean absorbent test paper to 0.01 g.
2. Place the specimen on the paper beneath the documented 100 g test mass for
   five minutes using a flat load spreader.
3. Remove the specimen without wiping the paper and reweigh the paper.
4. Record transferred mass, wet-halo dimensions, free droplets, and photographs.

Transferred mass is a screening metric, not a vapour-loss measurement. Use a new
paper for every replicate.

## Stage F - open-air drying

Place each specimen on its own nonabsorbent labelled support. Record mass,
diameter, thickness, appearance, and 1 kHz impedance at `0`, `2`, `8`, and
`24 hours`. Record temperature and relative humidity whenever available. Do not
rehydrate specimens during this stage.

## Stage G - final inspection

Photograph both faces and the edge. Record cracks, curling, shrinkage, residue,
electrode staining, biological growth, odour, tack, and handling condition.
Retain representative specimens sealed and labelled until Tristan reviews the
campaign disposition.

# Analysis and acceptance

## Calculations

For each route calculate:

- mean, median, range, and coefficient of variation for initial 1 kHz impedance;
- median post-compression impedance drift;
- individual thickness recovery after five minutes;
- transferred mass in the leakage test;
- mass, diameter, thickness, and impedance change through 24 hours.

Coefficient of variation is `100 x standard deviation / mean`. Do not calculate
it from fewer than three valid replicates.

## Hard gates

| Gate | Requirement |
|---|---|
| Internal cure | Witness has no liquid core, dry pocket, or gross nonuniformity |
| Handling | No fracture, free-running liquid, or loss of usable contact surface in ten cycles |
| Electrical contact | All replicates produce stable in-range readings at all three frequencies |
| Repeatability | Initial 1 kHz impedance coefficient of variation is at most 20% |
| Electrical durability | Route median 1 kHz drift after compression is at most 25% |
| Recovery | Every replicate returns to at least 90% of initial thickness after five minutes |
| Leakage | Every replicate transfers no more than 0.10 g in five minutes |
| Fixture integrity | Reference resistor drift is at most 2%; no electrode corrosion or fixture failure |

Any single hard-gate failure prevents that route from winning. Report all data;
do not discard an inconvenient replicate unless a separately documented fixture
or operator fault invalidated it before the result was known.

## Disposition

- **SELECTED:** passes every hard gate and wins the decision rule.
- **PASS / NOT SELECTED:** passes every hard gate but ranks second.
- **RETEST REQUIRED:** campaign invalidated by a documented fixture, instrument,
  or preparation-control failure.
- **FAILED:** one or more valid specimens fail a hard gate.

If both routes fail, do not improvise a new concentration. Close
`HYDROGEL-CARRIER-001` and propose a separately identified formulation campaign.
Passing this screen authorizes only a later passive mock-tip plan. It does not
authorize plating chemistry.

\clearpage

# Campaign worksheet

## Approval and materials

| Field | Record |
|---|---|
| Campaign suffix | |
| Operator | |
| Date range | |
| Tristan approval to begin | |
| Evidence directory | `Chemistry/Images/HYDROGEL-CARRIER-001/` |
| Total procurement before shipping | CA$ |
| Budget pass | Pass / Fail |

| Code | Supplier / product | Grade / identity | Lot | Received | Price | Accepted |
|---|---|---|---|---|---:|---|
| ALG | | | | | | Pass / Fail |
| CA | | | | | | Pass / Fail |
| AGR | | | | | | Pass / Fail |
| NACL | | | | | | Pass / Fail |
| WATER | | | | | | Pass / Fail |

## Solution and batch record

| Field | NaCl | Alginate | Calcium bath | Agar |
|---|---:|---:|---:|---:|
| Target mass g | 2.922 | 2.00 | 2.00 | 2.00 |
| Actual mass g | | | | |
| Final volume mL | 500.0 | 100.0 | 100.0 | 100.0 |
| Water lot | | | | |
| Start time | | | | |
| Peak temperature C | N/A | Ambient | Ambient | |
| Rest / treatment time | N/A | | 60 min | 60 min |
| Appearance | | | | |
| Deviations | | | | |

| Witness | Internal condition | Photograph | Batch disposition |
|---|---|---|---|
| ALG-2-W | | | Pass / Fail |
| AGR-2-W | | | Pass / Fail |

\clearpage

## Fixture and calibration

| Field | Record |
|---|---|
| Electrode material / active diameter | |
| Fixture revision / photograph | |
| Uncompressed stop mm | |
| 80% compression stop mm | |
| Electrode cleaning method | |
| Reference resistor ID / value | |
| Initial measured value | |
| Final measured value | |
| Reference drift % | |
| Open/short calibration complete | 100 Hz / 1 kHz / 10 kHz |
| Test level / bias | 0.1 V RMS / 0.0 V |

# Specimen worksheets

## Incoming and initial impedance

| ID | Mass g | Diameter A/B mm | Thickness 1/2/3 mm | 100 Hz Z / phase | 1 kHz Z / phase | 10 kHz Z / phase |
|---|---:|---|---|---|---|---|
| ALG-2-R1 | | | | | | |
| ALG-2-R2 | | | | | | |
| ALG-2-R3 | | | | | | |
| AGR-2-R1 | | | | | | |
| AGR-2-R2 | | | | | | |
| AGR-2-R3 | | | | | | |

Attach the five individual readings for every frequency as a continuation sheet
or machine-readable log. The table above records the median and phase summary.

## Handling, compression, and leakage

| ID | 10 handling cycles | 10 compression cycles | Recovered thickness % | Post-cycle 1 kHz Z | Drift % | Transfer g | Pass |
|---|---|---|---:|---:|---:|---:|---|
| ALG-2-R1 | | | | | | | |
| ALG-2-R2 | | | | | | | |
| ALG-2-R3 | | | | | | | |
| AGR-2-R1 | | | | | | | |
| AGR-2-R2 | | | | | | | |
| AGR-2-R3 | | | | | | | |

## Drying series

Use one row per specimen at each time point.

| ID | Hour | Mass g | Diameter mm | Thickness mm | 1 kHz Z | Phase | Appearance / failure |
|---|---:|---:|---:|---:|---:|---:|---|
| | 0 | | | | | | |
| | 2 | | | | | | |
| | 8 | | | | | | |
| | 24 | | | | | | |
| | 0 | | | | | | |
| | 2 | | | | | | |
| | 8 | | | | | | |
| | 24 | | | | | | |

Continue until all six specimens are recorded.

## Route summary and approval

| Result | Alginate | Agar |
|---|---:|---:|
| Witness cure | Pass / Fail | Pass / Fail |
| Initial 1 kHz median | | |
| Initial 1 kHz CV % | | |
| Median post-cycle drift % | | |
| Minimum recovery % | | |
| Maximum transferred mass g | | |
| All hard gates | Pass / Fail | Pass / Fail |
| Final disposition | | |

Selected route: ____________________  
Reason: ________________________________________________________________  
Open limitations: ______________________________________________________  
Tristan approval / date: _______________________________________________

# Safety, storage, and waste

- Wear splash eye protection and gloves during solution preparation and gel
  handling.
- Add calcium chloride to water gradually; dissolution may warm the solution.
- Guard against hot agar, hot glassware, steam, splashes, and boil-dry.
- Keep the LC1020E and its connectors dry. Only the removable electrode faces
  contact specimens.
- Never apply DC to chloride-bearing specimens. Stop on unexpected gas,
  discolouration, odour, corrosion, or heating.
- Keep this programme separate from copper compounds, plating residues, SAT,
  food preparation, and NanoArc hardware.
- Label retained specimens and liquids `LAB - NOT FOOD`.
- Do not assume drain or household disposal. Hold all specimens and liquids
  until Tristan reviews the recorded ingredients and local disposal route.

# References

1. FNIRSI, [LC1020E product specifications and measurement modes](https://www.fnirsi.com/products/lc1020e), accessed 2026-08-13.
2. K. Ino et al., "Hydrogel electrodeposition based on bipolar electrochemistry," *Lab on a Chip* 18 (2018), 2425. [DOI 10.1039/C8LC00465J](https://doi.org/10.1039/C8LC00465J).
3. J. B. Meloni et al., "Design of gel electrolytes for electrochemical studies on metal surfaces with complex geometry," *Electrochimica Acta* 197 (2016), 228-236. [Open manuscript](https://www.epfl.ch/labs/tic/wp-content/uploads/2018/10/art8.pdf).
4. NanoArc, `Chemistry/Proposals/Chemistry_Applications_Idea_Register.md`, current revision.
5. NanoArc, `/home/tristan/Documents/tech_docs/ACE_RevB_RevC_Modular_Applications_Proposal.md`, current revision.