High-resolution 3D printing and skin gas sensors drive flexible medical wearables

Advances in manufacturing techniques are changing the way modern electronics are made. In the field of flexible devices, used for things like healthcare monitoring and soft robotics, old methods are being replaced by more flexible and easy-to-scale technologies. Traditional methods like casting and lithography have been dependable but struggle with very small, complex, or oddly shaped designs.

These challenges are even bigger with wearable electronics, which need to be comfortable, fit well, and be durable. To overcome these issues, experts are turning to high-resolution 3D printing techniques, where Digital Light Processing (DLP) stands out as a top choice.

Advancements in DLP 3D printing

DLP 3D printing stands out because it can create very detailed designs with high precision, using light to harden layers of special liquid. This method makes intricate structures faster and more accurately than older methods. It also allows the use of a wider range of materials, making it possible to include mechanical, electrical, and even biological features all in one print.

One exciting development is grayscale DLP printing. This method lets different levels of stiffness and density be included in the same object. It’s particularly useful for creating responsive gadgets like pneumatic actuators that can bend, twist, or compress as needed. These are valuable in areas such as soft robotics and surgery tools that need to move precisely and adjust to fit body tissue.

Another big step forward is in the materials used for printing. Now, DLP printing can use self-healing hydrogels that fix themselves when damaged, conductive liquid metals that keep working even when they’re bent, and biodegradable elastomers that can be disposed of in an eco-friendly way. These materials mean that 3D-printed objects are not only more flexible and long-lasting, but also better for the environment.

Sensor and energy innovations

In sensor applications, DLP printing allows for the creation of small, high-quality parts. Dome-shaped capacitive sensors made from ionogels are very sensitive, detecting even minor changes, which are crucial for activities like tracking movement and monitoring health. Also, rotaxane hydrogel-based strain sensors show strong resistance to wear and tear, which is important for long-term use, where devices may be bent or stretched repeatedly.

For energy solutions, DLP printing makes it possible to create biomimetic triboelectric nanogenerators that efficiently turn physical movement into electrical energy by mimicking natural processes. Alongside these are custom-designed supercapacitors, which are improved for better energy storage and less energy loss, making them ideal for small, wearable energy storage solutions.

The merging of precise fabrication with versatile materials has led to new creative possibilities for developers. By bringing engineering and material science together in one seamless process, DLP 3D printing allows for quick design and launch of smart, light, and compact electronic systems. This shows that DLP is useful not only for prototyping but also for actual manufacturing in both research and industry.

Non-invasive health via skin gases

While creating new flexible electronic devices is essential, significant progress is also being made in how these devices can detect and interpret data. Researchers at Northwestern University have developed a wearable gas sensor platform that can detect chemical compounds released from the skin. This innovation offers a new way to monitor the body, providing insights that once needed invasive methods or large diagnostic equipment.

The skin releases various gases—like water vapor, carbon dioxide (CO₂), and different volatile organic compounds (VOCs)—that can reveal information about the body’s condition. Understanding this, the Northwestern team developed a non-contact device that gathers and analyzes these emissions without touching the skin, avoiding irritation or damage to sensitive tissues.

The device features a tiny chamber, just 2 cm by 1.5 cm, that sits slightly above the skin. Inside, there are sensors for detecting gases, an electronic circuit, a battery that can be recharged, and a programmable valve that manages air exchange. This valve lets the device sample the air by opening for baseline readings and then closing to focus on gases from the skin.

This method of measuring allows for accurate reading by avoiding the impact of environmental changes. If left open all the time, room conditions might interfere with readings. On the other hand, keeping it closed could change skin emissions. The valve-based approach helps collect real-time data without distortion and keeping it realistic.

The data collected is sent via Bluetooth to a smartphone or tablet, allowing for ongoing remote monitoring by doctors or the patients themselves. This supports healthcare that doesn’t always require in-person visits. It’s especially useful for those with compromised skin barriers, like people living with diabetes, eczema, or chronic wounds, as well as newborns or elderly patients who have more fragile skin.

One essential use of this sensor is in wound care management. Increases in water vapor, CO₂, and VOCs from wounds can signal bacterial growth or problems with healing. Early detection of these changes helps intervene sooner, reducing the risks of sepsis or incorrect use of antibiotics. Monitoring healing progress remotely enables better clinical decisions, vital for treating diabetic ulcers, a leading cause of non-traumatic amputations globally.

The same technology can apply to occupational health, where it’s crucial to monitor skin exposure to environmental toxins. Since the skin is a major contact point with the environment, detecting harmful substances entering through it is important for those working in chemical manufacturing, farming, or dealing with hazardous waste. This device can help spot overexposure before it shows symptoms.

Fabrication and sensing in wearables

The breakthroughs in DLP 3D printing and skin gas sensing are paving the way for the future of wearable tech. With 3D printing, you can customize devices to perfectly fit your body and needs. Meanwhile, gas sensing offers new ways to understand what’s happening inside your body without any contact.

Combining these technologies could lead to smart health devices that adjust to your personal needs and constantly monitor your health and surroundings. Imagine wearing a 3D-printed sleeve with sensors that can spot early signs of swelling or infection. This could wirelessly connect with health apps to give you personalized care based on live data.

These advancements also align with sustainability goals in tech production by using biodegradable polymers and recyclable hydrogels, which are easier on the planet. Plus, smaller sensor systems can replace big, energy-guzzling lab equipment, making them more resource-friendly.

Beyond medical uses, gas-sensing wearables can check how well skin products work, keep track of how hydrated athletes are, and see if transdermal drug delivery is doing its job. In everyday health and wellness, these devices can monitor pollutants affecting your skin or even help test mosquito repellents by tracking gases like CO₂.