# openQCM Q-1

> Source page: https://openqcm.com/about-openqcm-q-1
> Markdown version for AI agents and readers of plain text. Site guide: https://openqcm.com/llms.txt · Everything in one file: https://openqcm.com/llms-full.txt

_Benchtop · QCM-D · one overtone at a time_

openQCM Q-1 does not wait for the crystal to oscillate: it questions it. A synthesiser sweeps a band of frequencies across the resonance and, at every step, the instrument reads how much signal passes and with what phase. From the shape of that curve come frequency and dissipation, one overtone at a time.

## Key figures

- n ≤ 9: odd overtones, 5 MHz crystals
- ~1.0 s: per overtone
- ≤ 2.0 Hz: frequency SD in liquid, acceptance test
- ~50 µl: flow cell

## The principle: A sweep, then a curve.

An AD9851 direct digital synthesiser excites the crystal at one frequency after another around the chosen harmonic, and an AD8302 detector measures gain and phase across it at every step. When the curve is complete, a peak-detection algorithm finds the resonance frequency; the width of the peak at a calibrated level below its maximum gives the dissipation. The crystal is interrogated passively, so its parameters are read without an oscillator circuit pulling on them.

## Overtones: Choose the depth you look at.

Q-1 follows one harmonic per run: the fundamental or an odd overtone, up to the 9th with 5 MHz crystals and the 5th with 10 MHz crystals. Higher overtones probe a thinner slice of a soft film. The software lists the peaks found at calibration and you pick the one to follow; to sweep all of them in every cycle, there is NEXT.

## Calibration: Once per crystal.

Every time you change the sensor, a calibration sweep of about a minute and a half maps the crystal's peaks and the baseline of the electronics, corrected with a least-squares polynomial fit. Press start, wait about 30 seconds for the first data, and frequency, dissipation and temperature are saved to CSV, with optional raw sweep files: frequency, amplitude, phase.

## Fluidics: Pump in, or pump out.

The cell holds about 50 µl. A syringe pump usually pushes the liquid through it. With a peristaltic pump, the manual suggests placing the pump downstream so that it pulls the liquid from the reservoir through the cell: less pressure on the seal, less risk of leaks.

## Materials: Pick the right window.

The wetted parts are the window and an FKM (Viton) O-ring. PMMA windows are clear but swell and dissolve in many organic solvents, ethanol included: with organic solvents, use a PTFE window.

## Validation: What every unit has to pass.

Each assembled unit is tested with a 10 MHz AT-cut crystal, at least 30 minutes in air and 35 minutes in static deionized water: frequency standard deviation ≤ 2.0 Hz in liquid, dissipation standard deviation ≤ 0.2 × 10⁻⁶ in air and ≤ 0.5 × 10⁻⁶ in liquid, equilibrium in about 10 and 20 minutes.

## Specifications

### Sensor

- **Crystals:** 5 and 10 MHz, 14 mm, wrapped electrode (single-side contact)
- **Flow cell:** ~50 µl
- **Wetted parts:** PMMA or PTFE window, FKM (Viton) O-ring

### Measurement

- **Quantities:** Frequency and dissipation
- **Method:** Scalar network analysis: AD9851 DDS sweep, AD8302 gain and phase detector
- **Overtones:** One at a time; up to the 9th (5 MHz) or 5th (10 MHz)
- **Sampling:** ~1.0 s per overtone
- **Temperature:** MCP9808 in the sensor module (monitoring)

### Build

- **Case:** Nylon PA2200
- **Dimensions:** 143.1 × 66.8 × 26 mm
- **Weight:** 50 g
- **Power:** USB, 5 V

### Software

- **Language:** Python, open source
- **Data:** CSV, optional raw sweep files
- **Systems:** Windows, macOS, Linux

## Related pages

- [Design](https://openqcm.com/openqcm-q-1-design)
- [Electronics](https://openqcm.com/openqcm-q-1-electronics)
- [Software](https://openqcm.com/openqcm-q-1-software)
- [Tech specs](https://openqcm.com/openqcm-q-1-tech-specs)
- [Gallery](https://openqcm.com/openqcm-q-1-gallery)
- [Electrochemistry module](https://openqcm.com/about-openqcm-eqcm-q1)

## Downloads

### Software

- [Executable for Windows](https://openqcm.com/downloads/q-1/software/openqcm-q-1-software-2.1-windows.zip) (ZIP)
- [Python source code](https://openqcm.com/downloads/q-1/software/openqcm-q-1-software-2.1-source.zip) (ZIP)

### Firmware

- [Teensy 4.0 firmware](https://openqcm.com/downloads/q-1/software/openqcm-q-1-firmware-2.1-teensy40.zip) (ZIP)

### Docs

- [User manual](https://openqcm.com/downloads/q-1/openqcm-q-1-user-manual.pdf) (PDF)

## Buy or ask

- Store: https://store.openqcm.com/
- Contact: https://openqcm.com/contacts

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openQCM by Novaetech S.r.l., Pompeii, Italy · Buy: https://store.openqcm.com/ · Contact: info@openqcm.com · https://openqcm.com/contacts