phyphox

Review by eFreeware

Most of us carry a phone with a stack of sensors inside it and never give them a second thought. The accelerometer keeps the screen upright, the magnetometer points a compass, the microphone picks up voices, and that is roughly where the story ends for everyday use. phyphox, a free app from RWTH Aachen University, takes those same components and treats them as laboratory instruments, which is a much more interesting way to look at a device you already own.

The pitch is simple: the sensors are already there, and the app gives you a way to read them, run structured experiments with them, and get the numbers out afterward. It is an education app in the Education category, rated for Everyone, and it has been available since September 2016. More than a million installs and a 4.7 average from 8,593 ratings suggest it has found a real audience among students, teachers and hobbyists rather than sitting in a niche corner of the store.

How a session actually works

The core of the app is a catalog of pre-defined experiments. You pick one and press play, and the app starts collecting readings from whichever sensor that experiment uses, analyzing the data as it goes and showing the result. There is no setup ritual to learn before the first run, which matters when the point is to demonstrate something in front of a class or satisfy a sudden curiosity at home.

What makes the design useful beyond a single demo is the export step. Raw data and the analyzed results can both be written out in CSV, TSV or Excel format, so an experiment started on a phone can continue in a spreadsheet or a proper analysis tool. The developer notes that the Excel export now uses xlsx and has dropped the old 65,535-row ceiling, which widens the range of experiments whose full data can leave the app in one file.

The phone itself serves as the instrument. A handset can serve as a pendulum for measuring local gravitational acceleration, as a 3D magnetometer, or as a sonar. Those three examples set the tone well: the experiments are physical, measurable and tied to sensors that are genuinely present in the hardware, not simulations of them.

The sensor list and what it enables

The supported hardware covers the accelerometer, magnetometer, gyroscope, light sensor, pressure sensor, microphone, proximity sensor, GPS, camera and LiDAR or time-of-flight sensors. That spread is what allows the experiment catalog to range from motion and magnetism to acoustics and atmospheric pressure, and it is the reason the app can promise a sonar experiment at all.

One caveat: not every phone carries every sensor. A device without a pressure sensor or a LiDAR module simply cannot run the experiments that depend on them, so what you can do depends partly on the handset in your pocket. Checking the sensor list against your own phone before planning a lesson around a particular experiment is the sensible move.

The recent changelog shows the catalog is still growing. A spectroscopy experiment and a stroboscope experiment have been added, and the tone generator has been redesigned with support for up to three tones, selectable waveforms and panning. Those additions lean toward the acoustics and optics side of physics, which broadens the app's usefulness for teachers who want demonstrations that are audible or visible rather than only numerical.

Building and running your own experiments

Beyond the ready-made catalog, the app lets you define your own experiments. You choose the sensor inputs, set up the analysis steps and design the views that form the interface, using a web editor hosted at phyphox.org. The analysis side is not limited to trivial arithmetic; it includes simple operations such as adding two values alongside more advanced methods like Fourier transforms and crosscorrelation, drawn from a toolbox of analysis functions.

Finished experiments can be shared with colleagues, students and friends, which turns the editor into a way of distributing a teaching setup rather than just a personal tool. A teacher can build an experiment once and hand it to a class; a student can put together something for a project and pass it on.

There is also a remote-control option that I find particularly practical in a teaching setting. From any PC on the same network as the phone, you can drive the experiment through a web interface, and nothing needs to be installed on that computer beyond a modern web browser. That means the phone can sit taped to a pendulum or fixed to a moving object while the person running the demonstration watches and controls it from a laptop across the room.

What it asks of you and your hardware

The requirements are modest but real. The remote-control feature depends on the PC and the phone being on the same network, so it is a classroom or home-network convenience rather than something that works from anywhere. Custom experiments depend on the web editor, which means a browser at the point where you build them.

The sensor caveat is the other practical limit. Since some sensors are not present on every phone, an experiment that works beautifully on one handset may be unavailable on another. Anyone planning to rely on a specific measurement should confirm the hardware supports it first.

On the cost side, there is little to weigh. The app is free, carries no ads and offers no in-app purchases, so nothing in the experience is gated behind a payment or interrupted by advertising. For a tool used in schools and universities, that combination is a meaningful part of its appeal.

Who gets the most from phyphox

Physics teachers are the most obvious audience. The pre-defined experiments give a lesson something concrete to measure, the remote control keeps the phone out of the way while the class watches, and the export formats let students take real data into their own analysis. Being able to author and share custom experiments means a teacher can tailor the catalog to a specific syllabus rather than working around what ships with the app.

University students and hobbyists are close behind. Anyone working through mechanics, acoustics or optics can use the phone as a measuring device for coursework or personal projects, and the analysis toolbox covers enough ground that a custom experiment can go beyond a simple readout. The three-tone generator and the new stroboscope and spectroscopy experiments add options for anyone interested in sound and light.

The wider audience is the curious. Someone who wants to understand what the sensors in a phone actually do, and to see numbers attached to the physical world around them, will find the app approachable because the ready-made experiments start with a single button. The interface language options have expanded too, with Gujarati, Korean and Tamil added recently, which helps the app reach students who work in those languages.

A free instrument for the classroom and beyond

phyphox occupies a useful spot: it takes hardware people already own and gives it a scientific purpose, without charging for the privilege or interrupting the work with advertising. The combination of a ready-to-run catalog, a flexible editor and clean data export covers the whole arc from demonstration to analysis, and the remote-control feature solves a genuine practical problem in teaching spaces.

The trade-offs are the usual ones for phone sensors. Custom work depends on the web editor, remote control depends on both devices sharing a network, and the available experiments depend on which sensors your phone carries. None of these undercut the core idea; they simply define the conditions under which it works best.

If you teach physics, study it, or just want to see what the sensors in your handset can measure, this is an easy recommendation. It is free, it is ad-free, and it turns a phone into something closer to a lab instrument. The 4.7 average from more than 8,500 ratings suggests plenty of people have already reached the same conclusion.

What's new in version 1.2.1

New spectroscopy experiment New stroboscope experiment Redesigned tone generator with up to three tones, waveforms and panning Replace old Excel export format "xls" with "xlsx", removing the old limit of 65535 lines New languages: Gujarati, Korean and Tamil Select data when clearing New setting to change the default filename Full screen views of graphs and camera previews move controls to the right when in landscape Improved edit boxes Full changelog at https://phyphpox.org/changelog